3D-Printed Thermite Brings The Heat, And The Safety

September 10, 2020 by Kristina Panos 15 Comments

Thermites are a double-edged sword. Packing a tremendous energy density, and eager to produce tremendous heat when ignited, thermite is great for welding train tracks. But sometimes you might be looking for a little more finesse. A new approach to 3D printing thermites might just be able to tame the beast.

Most of us do our soldering while sitting safely indoors in a comfortable climate. The biggest dangers we’re likely to face are burnt fingertips, forgetting the heat shrink, or accidentally releasing the smoke monster. But outside of our homes and workshops, there’s a lot of extreme joining of metals going on. No matter where it’s done, welding and brazing in the field requires a lot of equipment, some of which is unwieldy and even more difficult to move around in harsh conditions.

Welding railroad tracks with thermite. Image via YouTube

The utility of brazing is limited by all the complex scaffolding of hardware required to support it. This limiting factor and the discovery of thermite led to exothermic welding, which uses an energetic material to provide enough heat to melt a filler metal and join the pieces. Energetic materials can store a lot of chemical energy and forcefully release it in a short period of time.

Thermites are made of metal oxide and metal powder, often iron oxide and aluminium. When ignited by a source of high heat, thermite compounds undergo an exothermic reduction-oxidation (redox) reaction as the aluminium reduces the number of electrons in the iron oxide atoms. More heat makes the reaction run faster, generating more heat, and so on. The result is molten iron and aluminium oxide slag.

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Exotic Device Gets Linux Support Via Wireshark And Rust

August 20, 2020 by Sven Gregori 10 Comments

What can you do if you have a nice piece of hardware that kinda works out of the box, but doesn’t have support for your operating system to get the full functionality out of it? [Harry Gill] found himself in such a situation with a new all-in-one (AIO) water cooling system. It didn’t technically require any operating system interaction to perform its main task, but things like settings adjustments or reading back statistics were only possible with Windows. He thought it would be nice to have those features in Linux as well, and as the communication is done via USB, figured the obvious solution is to reverse engineer the protocol and simply replicate it.

His first step was to set up a dual boot system (his attempts at running the software in a VM didn’t go very well) which allowed him to capture the USB traffic with Wireshark and USBPcap. Then it would simply be a matter of analyzing the captures and writing some Linux software to make sense of the data. The go-to library for USB tasks would be libusb, which has bindings for plenty of languages, but as an avid Rust user, that choice was never really an issue anyway.

How to actually make use of the captured data was an entirely different story though, and without documentation or much help from the vendor, [Harry] resorted to good old trial and error to find out which byte does what. Eventually he succeeded and was able to get the additional features he wanted supported in Linux — check out the final code in the GitHub repository if you’re curious what this looks like in Rust.

Capturing the USB communication with Wireshark seems generally a great way to port unsupported features to Linux, as we’ve seen earlier with an RGB keyboard and the VGA frame grabber that inspired it. If you want to dig deeper into the subject, [Harry] listed a few resources regarding USB in general, but there’s plenty more to explore with reverse engineering USB.

Modified Bricks Can House Energy, Too

August 16, 2020 by Kristina Panos 43 Comments

What if building an emergency battery were as easy as painting conductive plastic onto bricks, stacking them, and charging them up? Researchers at Washington University in St. Louis have done just that — they’ve created supercapacitors by modifying regular old red bricks from various big-box hardware stores.

The bricks are coated in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a conductive polymer that soaks readily into the bricks’ porous surface. When the coated brick is connected to a power source such as a solar panel, the polymer soaks up ions like a sponge. PEDOT:PSS reacts with the iron oxide in the bricks, the rust that gives them their reddish-orange color. Check out the demonstration after the break — it’s a time lapse that shows three PEDOT-coated bricks powering a white LED for ten minutes.

We envision a future where a brick house could double as a battery backup when the power goes out. The researchers thought of that too, or at least had their eye on the outdoors. They waterproofed the PEDOT-coated bricks in epoxy and found they retain 90% of their capacitance and are still efficient after 10,000 charge-discharge cycles. Since this doesn’t take any special kind of brick, it seems to us that any sufficiently porous material would work as long as iron oxide is also present for the reaction. What do you think?

If you can get your hands on the stuff, PEDOT:PSS has all kinds of uses from paper-thin conductors to homebrew organic LEDs.

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Will 2020 Be The Year Of Rust In The Linux Kernel?

July 15, 2020 by Sven Gregori 55 Comments

One problem with modern programming languages is the reach their overly enthusiastic early adopters have nowadays thanks to the internet. As a result, everyone else’s first encounter with them are oftentimes some crude, fanboyish endeavors to rewrite every single established software project in that shiny new language — just because — which may leave an off-putting taste behind. However, Rust certainly seems to have outgrown this state by now, and with its rising popularity within the general developer population, it’s safe to say it will stick around. Will it fully replace C one day? Probably not, but there’s a big chance for coexistence, and [Nick Desaulniers] got the ball rolling for that within the Linux kernel.

Now, before you storm off pledging your allegiance to C by finding a new operating system: nothing is happening yet. [Nick] simply tested the waters for a possible future of Rust within the Linux kernel code base, which is something he’s planning to bring up for discussion in this year’s Linux Plumbers Conference — the annual kernel developer gathering. The interesting part is [Linus Torvalds]’s respone on the LKML thread, which leaves everyone hoping for a hearty signature Rust rant akin to his C++ one disappointed. Instead, his main concern is that a soft and optional introduction of the support in the build system would leave possible bugs hidden, and therefore should be automatically enabled if a Rust compiler is present — essentially implying that he seems otherwise on board.

We’ll see what comes of it, but with Rust language team lead [Josh Triplett] stating that enhancements benefiting and advancing a kernel integration are certainly imaginable for Rust itself, we might see interesting collaborations coming up in the near future. If you don’t want to wait for that and use Rust already today in a user-land driver, check out this 35c3 talk. And if that doesn’t go far enough for you, here’s a whole (non-Linux) kernel written in Rust.

Debugging For Sed — No Kidding

April 24, 2020 by Al Williams 13 Comments

If you do much Linux shell scripting, you’ve probably encountered sed — the stream editor — in an example. Maybe you’ve even used it yourself. If all you want to do is substitute text, it is easy and efficient. But if you try to do really elaborate editing, it is often difficult to get things right. The syntax is cryptic and the documentation is lacking. But thanks to [SoptikHa2] you can now debug sed scripts with a text-based GUI debugger. Seriously.

According to the author, the program has several notable features:

Preview variable values, both of them!
See how will a substitute command affect pattern space before it runs
Step through sed script – both forward and backward!
Place breakpoints and examine program state
Hot reload and see what changes as you edit source code
Its name is a palindrome

There’s only one word for that last feature: wow.

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Program Guesses Your Regular Expression

April 22, 2020 by Al Williams 12 Comments

We aren’t sure how we feel about [pemistahl’s] grex program. On the one hand, we applaud a program that can take some input samples and produce a regular expression. On the other hand, it might be just as hard to gather example data that produces the correct regular expression. Still, it is an interesting piece of code.

Even the author suggests not to use this as an excuse to not learn regular expressions, since you’ll need to check the program’s output. It is certain that the results will match your test cases, but it isn’t certain that it won’t accept things you didn’t expect. Bad regular expressions have been the source of some deeply buried bugs.

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Audio Processing In Rust

November 14, 2019 by Al Williams 4 Comments

[Michael] volunteers with emergency services, and sometimes has to monitor radio traffic. Sometimes there’s a lot to review, and to make it easier he wrote a noise gate — think of it as a squelch — to break apart recorded audio into parts. Rust has been gaining popularity for writing low level software, and that’s the language he uses. However, you’ll see even if you don’t know Rust, it is pretty easy to figure out.

For test data, [Michael] took some publicly-available recordings of air traffic control. Using some ready-made audio processing functions and a simple state machine makes the code easy to write.

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