Modern Wildfires And Their Effect On The Ozone Layer

April 26, 2022 by Zoe Skyforest 36 Comments

The ozone layer is a precious thing, helping protect the Earth from the harshest of the sun’s radiative output. If anything were to damage this layer, we’d all feel the results in a very short order indeed.

In the past, humanity has worked to limit damage to the ozone layer from our own intentional actions. However, it’s not just aerosol cans and damaged air conditioning systems that are putting it at risk these days. The fierce wildfires we’ve seen so much of in recent years are also having a negative effect. Let’s take a look at why the ozone layer matters, and how it’s being affected by these wildfires.

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Explosion Welding Goes Off With A Bang

April 25, 2022 by Zoe Skyforest 25 Comments

Welding is often a hot and noisy process. It generally involves some fancy chemistry and proper knowledge to achieve good results. Whether you’re talking about arc, TIG, or MIG, these statements all apply.

The same is true for explosion welding, though it’s entirely unlike any traditional hand welding methods you’ve ever seen before. Today, we’ll explore how this technique works and the applications it’s useful for. Fire in the hole!

Don’t Blow Them Apart, Blow Them Together!

Explosion welding occurs near-instantaneously, but is done in a progressive fashion. The angle of collision, as well as the speed of the explosive front, is key to getting a quality weld. Image credit: NASA, public domain

The technique of explosion welding is relatively new compared to other metal-joining techniques. In the two World Wars of the 20th century, pieces of shrapnel were often found stuck to armor plating. Close observation showed that shrapnel was in fact welding on to metal armor, rather than simply being embedded in such. Given that collisions between shrapnel and armor often occur without the extreme heat of typical welding operations, it indicated that it was instead great velocity of the impact between shrapnel and armor that was melding the metals together.

The same results were later recreated in the lab, and explosoin welding was developed into a refined technique after World War II. 1962 saw DuPont patent a process for explosion welding later to be known under the “Detaclad” trademark.

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Axiom’s Private ISS Mission Was No Space Vacation

April 25, 2022 by Tom Nardi 14 Comments

In an era where anyone with deep enough pockets can hitch a ride to the edge of space and back, you’d be forgiven for thinking that Axiom’s Ax-1 mission to the International Space Station was little more than a pleasure cruise for the four crew members. Granted it’s a higher and faster flight than the suborbital hops that the likes of William Shatner and Jeff Bezos have been embarking on, but surely it must still be little more than a publicity stunt organized by folks with more money than they know what to do with?

Thankfully, there’s a bit more to it than that. While the mission was privately funded, the Ax-1 crew weren’t just orbital sightseers. For one thing, there was plenty of real-world experience packed into the SpaceX Dragon: the mission was commanded by Michael López-Alegría, a veteran NASA astronaut, and crew members Larry Connor and Eytan Stibbe are both accomplished pilots, with the latter clocking in thousands of hours on various fighter jets during his time with the Israeli Air Force.

But more importantly, they had work to do. Each member of the crew was assigned a list of experiments they were to conduct, ranging from medical observations to the testing of new hardware. Of course there was some downtime — after all, if you spent $50 million on a ticket to space, you’d expect to have at least a little fun — but this wasn’t just a photo op: Axiom was looking for results. There was no hiding from the boss either, as López-Alegría is not just the Mission Commander, he’s also Axiom’s Vice President of Business Development.

Which makes sense when you consider the company’s ultimate goal is to use the ISS as a springboard to accelerate the development of their own commercial space station. The data collected during Ax-1 is going to be critical to Axiom’s path forward, and with their first module already under construction and expected to launch by 2025, there’s no time to waste.

So what did the crew members of the this privately funded mission to the International Space Station accomplish? Let’s take a look at a few of the more interesting entries from the docket.

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The Honda Takedown: How A Global Brand Failed To Read The Room

April 21, 2022 by Jenny List 141 Comments

Perhaps the story of the moment in the world of 3D printing concerns a Japanese manufacturer of cars and motorcycles. Honda has sent a takedown notice requesting the removal of models starting with the word “Honda” to the popular 3D printing model repository site Printables. It’s left in its wake puzzlement, disappointment, and some anger, but what’s really going on? Perhaps it’s time to examine what has happened and to ponder what it means for those who put online printable parts and accessories for cars or any other item manufactured by a large corporation.

If You Make Something, What Rights Do You Have?

Soichiro Honda with his 1964 Formula 1 car — Soichiro Honda, famous for being an engineer rather than a serial litigator. Roderick Eime, CC BY 2.0.

The story is that as far as we can glean from reports online, the takedown notice was sent only to Printables by the European arm of Honda, and was pretty wide-ranging with any Honda-related model in its scope. Printables complied with it, but as this is being written there are plenty of such models available from Thingiverse and other model repository sites.

Anyone who makes a career in content creation has by necessity to have a working knowledge of copyright and intellectual property law as it’s easy for the unwary to end up the subject of a nasty letter, so here at Hackaday while we’re not lawyers this is a subject on which we have some professional experience. What follows then is our take based on that experience, our view on Honda’s motivation, and whether those of you who put up 3D models have anything to worry about. Continue reading “The Honda Takedown: How A Global Brand Failed To Read The Room” →

Linux Fu: An Odd Use For Fork()

April 21, 2022 by Al Williams 46 Comments

If you are a Star Trek fan, you’ll probably remember the phrase “You have to learn why things work on a starship.” The truth is, in most episodes, knowing how to override another ship’s console or make gunpowder didn’t come in very handy, but boy when it did, it really saved the day. Linux is a lot like that. There are a few things you probably don’t need to know very often, but when you do need to know, it makes a huge difference. In this particular post, I want to look at an odd use of the fork system call. For many purposes, you’ll never need to know this particular irregular use. But when you need it, you are really going to need it.

This is actually based on an old client of mine who used Unix to run a massive and very critical report every day. The report had a lot of math since they were trying to optimize something and then generate a lot of reports. In those days, the output of the report was on old green-bar paper on a line printer. The problem was that the report took something like 14 hours to run including the printouts. If someone discovered something wrong, there was no time to run the report again because the next day’s report would have to start before the second run would finish.

The client had a bunch of Windows programmers and — at that time — there wasn’t anything really analogous to a real fork call in Windows. I looked at the code and realized that probably most of the code was spending time waiting to print the output. The computer had multiple CPUs and there were multiple printers, but that one program was hanging on the one printer. There was a lot of data, so writing it to a database and then running different reports against it wasn’t a great option. The answer was to use the power of fork. With a change in the code that took less than 30 minutes, the report ran in five hours. They were very pleased.

So how did I do it? The answer lies in how fork works. Just about every time you see a fork, you see some sort of exec call to start a new program. So if you think about fork at all, you probably think it is part of how you start a new program and, most of the time, that’s true. Continue reading “Linux Fu: An Odd Use For Fork()” →

A Rotary Encoder: How Hard Can It Be?

April 20, 2022 by Al Williams 70 Comments

As you may have noticed, I’ve been working with an STM32 ARM CPU using Mbed. There was a time when Mbed was pretty simple, but a lot has changed since it has morphed into Mbed OS. Unfortunately, that means that a lot of libraries and examples you can find don’t work with the newer system.

I needed a rotary encoder — I pulled a cheap one out of one of those “49 boards for Arduino” kits you see around. Not the finest encoder in the land, I’m sure, but it should do the job. Unfortunately, Mbed OS doesn’t have a driver for an encoder and the first few third-party libraries I found either worked via polling or wouldn’t compile with the latest Mbed. Of course, reading an encoder isn’t a mysterious process. How hard can it be to write the code yourself? How hard, indeed. I thought I’d share my code and the process of how I got there.

There are many ways you can read a rotary encoder. Some are probably better than my method. Also, these cheap mechanical encoders are terrible. If you were trying to do precision work, you should probably be looking at a different technology like an optical encoder. I mention this because it is nearly impossible to read one of these flawlessly.

So my goal was simple: I wanted something interrupt driven. Most of what I found required you to periodically call some function or set up a timer interrupt. Then they built a state machine to track the encoder. That’s fine, but it means you eat up a lot of processor just to check in on the encoder even if it isn’t moving. The STM32 CPU can easily interrupt with a pin changes, so that’s what I wanted.

The Catch

The problem is, of course, that mechanical switches bounce. So you have to filter that bounce either in hardware or software. I really didn’t want to put in any extra hardware more than a capacitor, so the software would have to handle it.

I also didn’t want to use any more interrupts than absolutely necessary. The Mbed system makes it easy to handle interrupts, but there is a bit of latency. Actually, after it was all over, I measured the latency and it isn’t that bad — I’ll talk about that a little later. Regardless, I had decided to try to use only a pair of interrupts.

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Commodore C64: The Most Popular Home Computer Ever Turns 40

April 20, 2022 by Bil Herd 107 Comments

This year marks the anniversary of the most popular selling home computer ever, the Commodore 64, which made its debut in 1982. Note that I am saying “home computer” and not personal computer (PC) because back then the term PC was not yet in use for home computer users.

Some of you have probably not heard of Commodore, which is kind of sad, though there is a simple reason why — Commodore is no longer around to maintain its legacy. If one were to watch a documentary about the 1980s they may see a picture of an Apple computer or its founders but most likely would not see a picture of a Commodore computer in spite of selling tens of millions of units.

To understand the success of the C64 I would first back up and talk about the fabled era of home computers which starts with understanding the microprocessor of the day, the venerable 6502. Check out the video and follow along below.

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