Where Graph Theory Meets The Road: The Algorithms Behind Route Planning

April 4, 2024 by Maya Posch 32 Comments

Back in the hazy olden days of the pre-2000s, navigating between two locations generally required someone to whip out a paper map and painstakingly figure out the most optimal route between those depending on the chosen methods of transport. For today’s generations no such contrivances are required, with technology having obliterated even the a need to splurge good money on a GPS navigation device and annual map updates.

These days, you get out a computing device, open Google Maps or equivalent, ask it how you should travel somewhere, and most of the time the provided route will be the correct one, including the fine details such as train platform and departure times. Yet how does all of this seemingly magical route planning technology work? It’s often assumed that Dijkstra’s algorithm, or the A* graph traversal algorithm is used, but the reality is that although these pure graph theory algorithms are decidedly influential, they cannot be applied verbatim to the reality of graph traversal between destinations in the physical world.

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Wear Testing Different 3D Printer Filaments

April 2, 2024 by Jenny List 5 Comments

Over the couple of decades or so since it started to be available at an affordable level, 3D printing has revolutionized the process of making custom objects. But as anyone with a 3D printer will know, sometimes the materials don’t quite live up to the application. There is a huge variety of available filaments to help make better prints, but which one really is the most hard-wearing? [My Tech Fun] set out to measure the resistance to wear of a variety of different 3D printed materials.

The test takes a standard print made across a variety of different materials, and several of each using different manufacturers’ offerings. These are then put on a test rig that moves backward and forward twice a second, with the test piece rubbing against a steel shaft under pressure from a 2.5 kg weight.

As might be expected, the common and cheap PLA performed the worst while PETG, PA, and TPU performed the best. But for us the interesting part comes in the variance between brands; the best PLA sample outperforms the worst ABS and nearly equals the worst of the PETG. Proof that maybe you do get what you pay for.

The whole test is well worth a watch, and if you 3D print anything that might be subjected to mechanical stress you should find it to be of interest. If comparing filaments is something you’d like to see more of, we’ve featured some tests before.

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A Supercapacitor From Mushrooms

April 1, 2024 by Jenny List 28 Comments

The supercapacitor is an extremely promising energy storage technology, and though they have yet to reach parity with the best batteries in terms of energy density, offers considerable promise for a future of safe and affordable energy storage. Perhaps best of all from our point of view, they are surprisingly simple to make. A practical supercapacitor can be made on the bench by almost anyone, as the ever-resourceful [Robert Murray-Smith] demonstrates using mushrooms as his feedstock.

The idea of a supercapacitor is to replace the flat plate on the simple capacitor from your physics textbook with one that has as large a surface area as possible for charge to accumulate on. In this case the surface is formed from organic charcoal, a substance which retains something of the microscopic structure of whatever it was made from. Mushrooms are a good feedstock, because their mycelium structure has a naturally huge surface area. He takes us in the video below the break through the process of carbonizing them, much easier when you have a handy kiln than trying the charcoal-burner method, and then grinds them to a powder before applying them as a paste with a binder to a piece of graphite foil. With two of these electrodes and a piece of paper towel as a dielectric, he demonstrates a simple benchtop supercapacitor running a small electric motor for a surprisingly longer time than we expected.

We’d like to see further work on home made supercapacitors, as we believe they have immense potential as well as storing the stuff. Meanwhile, this is by no means the most unexpected supercapacitor material we’ve seen.

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Retrotechtacular: TOPS Runs The 1970s British Railroad

March 27, 2024 by Al Williams 29 Comments

How do you make the trains run on time? British Rail adopted TOPS, a computer system born of IBM’s SAGE defense project, along with work from Standford and Southern Pacific Railroad. Before TOPS, running the railroad took paper. Lots of paper, ranging from a train’s history, assignments, and all the other bits of data required to keep the trains moving. TOPS kept this data in real-time on computer screens all across the system. While British Rail wasn’t the only company to deploy TOPS, they were certainly proud of it and produced the video you can see below about how the system worked.

There are a lot of pictures of old big iron and the narrator says it has an “immense storage capacity.” The actual computers in question were a pair of IBM System/370 mainframes that each had 4 MB of RAM. There were also banks of 3330 disk drives that used removable disk packs of — gasp — between 100 and 200 MB per pack.

As primitive and large as those disk drives were, they pioneered many familiar-sounding technologies. For example, they used voice coils, servo tracking, MFM encoding, and error-correcting encoding.

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Hackaday Podcast Episode 263: Better DMCA, AI Spreadsheet Play, And Home Assistants Your Way

March 22, 2024 by Al Williams 4 Comments

No need to wonder what stories Hackaday Editors Elliot Williams and Al Williams were reading this week. They’ll tell you about them in this week’s podcast. The guys revisit the McDonald’s ice cream machine issue to start. This week, DIY voice assistants and home automation took center stage. But you’ll also hear about AI chat models implemented as a spreadsheet, an old-school RC controller, and more.

How many parts does it take to make a radio? Not a crystal radio, a software-defined one. Less than you might think. Of course, you’ll also need an antenna, and you can make one from lawn chair webbing.

In the can’t miss articles, you’ll hear about the problems with the x86 architecture and how they tried to find Martian radio broadcasts in the 1920s.

Miss any this week? Check out the links below if you want to follow along, and as always, leave your comments!

Direct download in DRM-free MP3.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Offset-Stem Keycaps

March 18, 2024 by Kristina Panos 3 Comments

Love it or hate it, I think this is a really cool idea. [Leo_keeb] has designed a new set of keycaps for the Happy Hacking Keyboard (HHKB). The keycaps’ stems are offset to the left or right in order to turn this once-staggered keyboard into an ortholinear object.

So, how do they feel? There is a slight wobble to them, according to [Leo_keeb] — it’s a bit like pressing the left or right side of Tab. But the actuation is smooth, they say.

As you can see, these resin keycaps weren’t designed with the typical Cherry MX profile in mind, they are made for the Topre capacitive key switches of the HHKB. (No, those aren’t weird rubber domes.)

When I asked about sharing the STLs, [Leo_keeb] advised me that they might be willing to release STLs for Cherry MX switches in the US layout if there is enough interest.

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Hackaday Links: March 17, 2024

March 17, 2024 by Dan Maloney 16 Comments

A friend of ours once described computers as “high-speed idiots.” It was true in the 80s, and it appears that even with the recent explosion in AI, all computers have managed to do is become faster. Proof of that can be found in a story about using ASCII art to trick a chatbot into giving away the store. As anyone who has played with ChatGPT or its moral equivalent for more than five minutes has learned, there are certain boundary conditions that the LLM’s ~~creators~~ lawyers have put in place to prevent discussion surrounding sensitive topics. Ask a chatbot to deliver specific instructions on building a nuclear bomb, for instance, and you’ll be rebuffed. Same with asking for help counterfeiting currency, and wisely so. But, by minimally obfuscating your question by rendering the word “COUNTERFEIT” in ASCII art and asking the chatbot to first decode the word, you can slip the verboten word into a how-to question and get pretty explicit instructions. Yes, you have to give painfully detailed instructions on parsing the ASCII art characters, but that’s a small price to pay for forbidden knowledge that you could easily find out yourself by other means.

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