Hackszine.com: Science Archives

Archive: Science

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September 24, 2008

Google Gadget that monitors Arduino sensor data

Matthew Karas sent us a hack for creating an iGoogle homepage interface for physical measurement devices. Using an Arduino and a python script, he found a clever way to send real-time sensor data to a Google Gadget, and it doesn't even require having a web server.

I managed to hack up an arduino to upload data to google docs in real time. I then created a real time data gadget and sent that to google home page. That way I can monitor a sensor network from anywhere, with minimal cash outlay. I don't need to have a web host. I did it in two evenings.

The python code can run on a laptop connected the the Arduino. This script reads sensor data from the device and then posts it to a Google Spreadsheet using the python gdata API. From there, you can easily use the spreadsheet as a datasource for a Google Gadget which is then embedded in iGoogle or wherever you want to view your sensor data.

He's posted the necessary code and instructions for making this work. You should be able to customize it for your own projects and get something like this up and running in no time flat.

Real Time Arduino Data To iGoogle Homepage
gdata - Google Data Python API

September 22, 2008

Plotting streaming data in real-time with Gnuplot

Our friend Thanassis Tsiodras, who you may remember as the creator of the offline Wikipedia reader, wrote in to tell us about a handy way to plot real-time data using standard unix tools.

For the last couple of years, I've been working on European Space Agency (ESA) projects - writing rather complex code generators. In the ESA project I am currently working on, I am also the technical lead; and I recently faced the need to provide real-time plotting of streaming data. Being a firm believer in open-source, after a little Googling I found Gnuplot; and quickly hacked a Perl script that spawns instances of Gnuplot and plots streaming data in real-time. Googling doesn't reveal anything similar, so I published it here.

You can easily pipe any data stream into his druveGnuPlots.pl script, choose the zoom and y-range and it will take care of reading in the data and passing it to Gnuplot with your specifications. This is pretty neat, since it means you can easily plot just about anything and all you need to do is get your measurements into a newline-delimited output format.

Visualize real-time data streams with Gnuplot

September 1, 2008

LEGO 3D printer

Gene Hacker created a 3D printer out of LEGO. It's like a lo-rez reprap that operates in polar coordinates instead of the more familiar cartesian system. This is still very alpha and his demos show some promising 3D blobs of frosting. With that in mind, however, most of the basic functionality of a rapid fabrication system is here. Hacker posted the necessaries to Instructables, so you should be able to replicate his design and put your mind to making it even better.

Build a Polar 3-D Printer from Legos [via BoingBoing]

August 31, 2008

Basement Apollo Guidance Computer

In November of 2000, John Pultorak got to thinking about building a replica of a 60's or 70's era digital computer from scratch. By 2001, he started placing orders for technical documentation and had chosen his target machine, a Block I Apollo Guidance Computer.

Four years later, in September 2004, he had completed a fully functioning replica of the worlds first integrated circuit computer.

In the 1960's, each Apollo moon mission had one AGC in the command module, and a second in the lunar module. These were used by astronauts to collect real-time flight information and control the spacecrafts' navigation and guidance systems. Almost half a century later, John Pultorak has one in his basement, and thanks to his remarkable documentation and collection of reference materials, you can have one in your basement too!

Block I Apollo Guidance Computer (AGC):
How to build one in your basement

August 25, 2008

Wii Physics

Wii Physics is a clever little homebrew app. You use the Wiimote to rotate, size and place objects on a stage. Pulleys, ropes, gears and joints can be used to connect objects together, and when you press the play button, a 2D physics system is turned on, causing the objects to fall and interact with each other.

You can download this for free and run it from the Homebrew Channel. If you're ambitious, you can also download the source, add new features, or base a new game off of it. It's written using libwiisprite, a library you'll want to check out if you're thinking of doing any 2D game dev for the Wii.

Wii Physics
libwiisprite

August 11, 2008

Super Mario World and quantum physics

You may recall a post last month about Kaizo Mario, the ridiculously cruel fan-made Super Mario World level. Hackszine reader Guy Russell sent us a link to an article on the Mechanically Seperated Meat blog that uses this level to visually illustrate the concept of the "Many Worlds Interpretation" of quantum physics.

One good example of this is the Quantum Suicide "experiment" that some proponents of the Many-Worlds Interpretation claim (I think jokingly) could actually be used to test the MWI. The way it works is, you basically run the Schrödinger's Cat thought experiment on yourself- you set up an apparatus whereby an atom has a 50% chance of decaying each second, and there's a detector which waits for the atom to decay. When the detector goes off, it triggers a gun, which shoots you in the head and kills you. So all you have to do is set up this experiment, and sit in front of it for awhile. If after sixty seconds you find you are still alive, then the many-worlds interpretation is true, because there is only about a one in 10¹⁸ chance of surviving in front of the Quantum Suicide machine for a full minute, so the only plausible explanation for your survival is that the MWI is true and you just happen to be the one universe where the atom's 50% chance of decay turned up "no" sixty times in a row. Now, given, in order to do this, you had to create about 10¹⁸ universes where the Quantum Suicide machine did kill you, or copies of you, and your one surviving consciousness doesn't have any way of telling the people in the other 10¹⁸ universes that you survived and MWI is true. This is, of course, roughly as silly as the thing about there being a universe where all the atoms in your heart randomly decided to tunnel out of your body.

But, we can kind of think of the multi-playthrough Kaizo Mario World video as a silly, sci-fi style demonstration of the Quantum Suicide experiment. At each moment of the playthrough there's a lot of different things Mario could have done, and almost all of them lead to horrible death. The anthropic principle, in the form of the emulator's save/restore feature, postselects for the possibilities where Mario actually survives and ensures that although a lot of possible paths have to get discarded, the camera remains fixed on the one path where after one minute and fifty-six seconds some observer still exists.

To create the many-worlds video, the author hacked together a custom version of the SNES9X emulator. The application, which you can download in source or binary form, allows you to record the hundreds retry attempts you make through a level. It then compiles all of the attempts into a single Quicktime video that represents all of Mario's potential histories.

Super Mario World vs. the Many-Worlds Interpretation of Quantum Physics
Previously: Cruel Super Mario World hack

August 4, 2008

Photos of the Large Hadron Collider

View of the CMS (Compact Muon Solenoid) experiment Tracker Outer Barrel (TOB) in the cleaning room. The CMS is one of two general-purpose LHC experiments designed to explore the physics of the Terascale, the energy region where physicists believe they will find answers to the central questions at the heart of 21st-century particle physics. (Maximilien Brice, © CERN)

The following link contains a number of high-res photographs from CERN of the Large Hadron Collider. It's set to begin testing this month, and I must say it's about the most beautiful thing I've ever seen.

Large Hadron Collider nearly ready

July 24, 2008

Farm Fountain - edible eco-sculpture

Equal parts hydroponic garden, aquarium, and interactive art, the Farm Fountain is an experiment in self-contained, indoor ecosystem design created by artists Ken Rinaldo and Amy Youngs. The idea is that you can raise edible fish and cycle their waste nutrients through a hanging garden which filters the water before returning it to the aquarium.

Their 4th generation Farm Fountain is currently on display at the Te Papa Museum in New Zealand until January 2009. From the Farm Fountain website:

This project is an experiment in local, sustainable agriculture and recycling. It utilizes 2-liter plastic soda bottles as planters and continuously recycles the water in the system to create a symbiotic relationship between edible plants, fish and humans. The work creates an indoor healthy environment that also provides oxygen and light to the humans working and moving through the space. The sound of water trickling through the plant containers creates a peaceful, relaxing waterfall. The Koi and Tilapia fish that are part of this project also provide a focus for relaxed viewing.

The plants we are currently growing include lettuces, cilantro, mint, basil, tomatoes, chives, parsley, mizuna, watercress and tatsoi. The Tilapia fish in this work are also edible and are a variety that have been farmed for thousands of years in the Nile delta.

A Basic Stamp program controls the pump mechanism, allowing the plants to be watered at regular intervals for a set period of time. Depending on available natural light, supplemental lighting can be provided by a combination of fluorescent and grow-spectrum LED lighting, switched from a standard light timer. Ken and Amy worked out a lot of the details during the construction of their 3rd Farm Fountain design (pictured above) and they've assembled a how-to instructional gallery which you can use to design your own Farm Fountain system.

There are a lot of external inputs required to keep the ecosystem healthy for a long period of time including fish food, PH and nitrate monitoring, and general gardening tasks. Once you've gotten accustomed to it, though, it's probably not much more work than maintaining a lawn, and a lawn can't give you tomatoes in the middle of winter.

Farm Fountain - a sculptural ecosystem you can eat

April 21, 2008

Post your Earth Day hacks

In celebration of my favorite planet, I'd like to open the comments up to any and all Earth Day hacks, links and activities. Think of it as an opportunity to quickly catalog a list of ideas and tools that can be used for the other 364 days of the year.

Here are a few simple things that you can do tomorrow. I figure it's as good a day as any to start forming a few practical habits, so for my list, I just chose a number of things that you can easily make a regular part of your day.

Bike to work. If you need to find a route, citybikemap.com is a good user contributed resource
Compost the garbage. If you don't have a composter, here are some construction ideas from Instructables: Sinmple Pentagon Composter; Mini Wooden Portable Compost Bin; Trench Composter
Avoid the purchase of anything with excess packaging
Turn lights off when not in use. Convert remaining incandescent bulbs to CFL
Check faucets and toilets for leaky valves. For your toilets, shut off the water while you are at work and see if the water level goes down in the tank. It's a common problem that's easy to fix.
Print no emails.
Bring a mug to work and use it instead of styrofoam or paper cups.
Reconnect with nature: start a garden; go for a hike; take the kids out and identify some plants and birds.
Reclaim some of the yard for native plants and grasses.
Encourage others to do the same, and share your own Earth-friendly tips and hacks.

You may be more or less ambitious, but I think this represents something that's feasible for much of the year. It'd be cool to get a read on what the hacker community is doing to make a positive impact on the globe, so make sure to post your own Earth Day hacks and resolutions in the comments.

April 3, 2008

Practical fluid mechanics

Mick West from Cowboy Programming posted a two part series to his blog titled Practical Fluid Dynamics. Originally written for Game Developer Magazine, it covers a number of clever (and down-to-earth) techniques for simulating the movement of fluids in games and other software environments where real-time speed and visual authenticity matter most.

Special attention is paid to the simulation of particulate matter being carried around within a fluid volume—think effects like smoke, fire, and bubbles. I know I've seen a number of people using particle systems to do this sort of thing, but the methods Mick describes are all based on a grid model where you represent the system with a velocity field and a density field. Unlike a particle system, these fields represent a continuous fluid surface, allowing you to measure the density and velocity of the fluid at any location on the surface by interpolating the values from the nearest cells in the field array.

Practical Fluid Mechanics

March 22, 2008

Easter egg anemometer

Here's something fun to do with the kids tomorrow after they've finished emptying those big plastic eggs of jelly beans and malted milk balls.

The basic ingredients are plastic eggs, a small DC motor from an old CD player, and a cheapo multimeter. It's a quick afternoon project, and you'll be able to measure the wind's speed—a useful addition to your toolkit for backyard experiments.

Easter Egg Anemometer (Wind Speed Meter)

March 19, 2008

From Nand to Tetris in 12 Steps

Shimon Schocken gave a really interesting Google Tech Talk titled From Nand to Tetris in 12 Steps. In the video, he describes a course where students design a complete virtualized computer system from scratch, building from the humble nand gate, to a functional cpu and memory architecture, to compiler software and an operating system, all culminating in a simple game that runs on the virtual hardware.

The hardware projects are done in a simple hardware description language and a hardware simulator supplied by us. The software projects (assembler, VM, and a compiler for a simple object-based language) can be done in any language, using the APIs and test programs supplied by us. We also build a mini-OS. The result is a GameBoy-like computer, simulated on the student's PC. We start the course (and this talk) by demonstrating some video games running on this computer, e.g. Tetris and Pong.

Building a working computer from Nand gates alone is a thrilling intellectual exercise. It demonstrates the supreme power of recursive ascent, and teaches the students that building computer systems is -- more than anything else -- a triumph of human reasoning.

It looks like most of the course materials are available online. The necessary hardware emulator and simulator software is open source and available from Shimon's website.

CS101 Digital Systems Construction
Video - Building a Modern Computer from First Principles [via Slash7]

March 16, 2008

Art Bots 2008

The fifth international ArtBots exhibit is being held on September 19-21 in Dublin Ireland. Whether you're interested in creating a robotic work of art, or a robot capable of producing its own works of art, you have till May 1st to submit an entry.

I've seen the output from this robot talent show / art fair for a few years now, and I'm really excited to see what happens this year. Are any of you folks planning on entering or attending?

Shown above: One of Bruce Shapiro's "Ribbon Dancer" robots. When activated, the robots are able to perform intricate dance routines by moving a ribbon through the air in choreographed patterns. It's the robot equivalent of an Olympic floor routine.

ArtBots 2008 Call for Works
Ribbon Dancer Robots

March 12, 2008

CNC hologram

I posted earlier this week about abrasion holography, a hologram technique that uses a network of simple arc shaped scratches to encode a visible, 3D hologram into a chunk of plastic. Carl was the first to comment on exactly what was on a number of peoples minds:

This is just crying out for someone to generate complex pictures using CNC.

Like many great ideas, someone has already worked this one out! William Beaty was kind enough to write back with a link:

The scratches need to be be almost perfectly smooth with no jaggies at all. Normal CNC doesn't work, but a couple months ago Evan at homeshopmachinist.net found that "drag engraving" does reduce the jaggies enough.

The photo above is Evan's cube, engraved on blackened copper. The top image is what you see in normal diffuse lighting. The bottom is one perspective of the hologram when viewed head-on under a point-source light. Evan writes:

The way this type of hologram is generated is to start with a 2d representation of the subject (the cube in this case). Then an arc is drawn using a point on the visible vertices and edges of the shape. A set of closely spaced points along all visible edges is then used to provide the anchor points for the radii of the arcs. The reason the image isn't perfect appearing is because of slight inaccuracies in the placement of the arcs (my fault) and some waviness in the copper plate which is only 26 gauge material.

There are a lot of creative possibilities with this one. First person to engrave a HACKS hologram on a copper business card wins a standing ovation.

Synthetic Holograms With a CNC Mill - Link
DIY Hand-Drawn Holograms - Link

March 8, 2008

DIY hand-drawn holograms

Typically the creation of a hologram involves lasers and various other expensive equipment and materials. William J. Beaty figured out a low-tech way to create your own holograms using a simple abrasion technique that requires only a compass and a chunk of plastic. He came across the idea while walking through a parking lot, noticing strange hand prints that seemed to float above or deep inside the surface of polished car hoods.

The images were naturally-occurring holograms. The owner of the car had obviously polished the hood with a dirty mit, and the millions of particles of grit in the mit traced out millions of nearly-parallel scratches in the black paint. The particular hand motion had created a geometry of abrasion patterns which turn out to be nearly identical to the interference patterns which make up those embossed-foil Benton whitelight [holograms].

So how do you make one? All you need is a spanner (compass with 2 needles) and a chunk of hard plastic such as Lexan. For simple flat shapes, you just draw the reference shape below where you want the hologram to appear. Set the diameter of the spanner to an inch or two, put one of the points on the shape and score a small arc across the plastic. You then repeat this process for a bunch of other points on the shape, leaving a number of small arc shaped scratches. When you observe the scratches in the light, you'll see a hologram of the shape that appears to float beneath the surface of the plastic.

The image above, from William's site, is actually a stereo photo of one of his holograms. You can cross your eyes to see the effect. The cube that reflects from the scratches appears different based on the angle you view it.

The depth of the hologram is related to the width of the spanner, so you can actually create three dimensional holograms using the same technique. William's FAQs have more details on doing this, as well as hints for creating opaque shapes that have other objects hidden behind them which are only viewable from certain angles.

Abrasion Holography - Link

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