Mining And Refining: Titanium, Our Youngest Industrial Metal

December 5, 2023 by Dan Maloney 9 Comments

Earlier in this series, we made the case for copper being “the metal that built technology.” Some readers took issue with that statement, noting correctly that meteoric iron and gold were worked long before our ancestors were able to locate and exploit natural copper outcroppings, therefore beating copper to the historical punch. That seems to miss the point, though; figuring out how to fashion gold decorations and iron trinkets doesn’t seem like building the foundations for industry. Learning to make tools from copper, either pure or alloyed with tin to make bronze? Now that’s how you build an industrial base.

So now comes the time for us to make the case for our most recent addition to humanity’s stable of industrial metals: titanium. Despite having been discovered in 1791, titanium remained locked away inside abundantly distributed ores until the 1940s, when the technological demands of a World War coupled with a growing chemical prowess and command of sufficient energy allowed us to finally wrest the “element of the gods” from its minerals. The suddenness of it all is breathtaking, too; in 1945, titanium was still a fantastically expensive laboratory oddity, but just a decade later, we were producing it by the (still very expensive) ton and building an entirely new aerospace industry around the metal.

In this installment of “Mining and Refining,” we’ll take a look at titanium and see why it took us over 11,000 years to figure out how to put it to work for us.

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Ejector Seats: The Rocket Chairs That Save Lives

November 29, 2023 by Lewin Day 36 Comments

Once upon a time, escaping an aircraft was a tricky business. You had to unstrap yourself, fling open a heavy glass canopy, and try to wrench yourself out of a small opening without getting smacked by the tail or chopped up by the propeller. Many pilots failed this difficult task, to the tragic loss of their lives.

Eventually, the human cost was heavy enough and militaries grew strained at having to train new pilots to replace the experienced ones lost to accidents and enemy fire. The ejection seat was developed to make escaping a plane as simple as tucking yourself in and pulling a big red handle. Let’s dive in and learn how it came to be.

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Why Gas Turbines Rule The World

November 18, 2023 by Al Williams 27 Comments

It is an interesting fact that the most efficient way to generate electricity — at least so far — is to spin the shaft of a generator. The only real question is how you spin it. Falling water works. Heat from a nuclear reaction is another choice. For many decades, the king of the hill was steam. Now, however, gas turbines rule the electric generator landscape, and [Construction Physics] explains why in a recent post.

With a steam turbine, something burns or otherwise generates heat that boils water. The steam spins the blades, which turns the generator. With a gas turbine, the system compresses air and mixes it with gas. The hot gasses then drive the turbine, which is more efficient than using the combustion to produce steam.

Turns out, the idea for the gas turbine is very old, but material science had to catch up to be practical. Inefficient compressors led to low operating pressures, which was good, in a way, because the materials couldn’t stand the heat and pressure. However, low pressures led to inefficient turbines that were not practical.

The post is long and covers a lot of details about Carnot, Brayton, and Rankine cycles. It is a fascinating read, and we learned a few new things. Bet you will, too.

Turbines are a little like jet engines, but they transfer more power to the turbine blade instead of generating thrust. Turbines show up in odd places today. Some odder than others.

Mining And Refining: Graphite

November 9, 2023 by Dan Maloney 26 Comments

In my teenage years I worked for a couple of summers at a small amusement park as a ride operator. Looking back on it, the whole experience was a lot of fun, although with the minimum wage at $3.37 an hour and being subjected to the fickle New England weather that ranged from freezing rains to heat stroke-inducing tropical swelter, it didn’t seem like it at the time.

One of my assignments, and the one I remember most fondly, was running the bumper cars. Like everything else in the park, the ride was old and worn out, and maintenance was a daily chore. To keep the sheet steel floor of the track from rusting, every morning we had to brush on a coat of graphite “paint”. It was an impossibly messy job — get the least bit of the greasy silver-black goop on your hands, and it was there for the day. And for the first few runs of the day, before the stuff worked into the floor, the excited guests were as likely as not to get their shoes loaded up with the stuff, and since everyone invariably stepped on the seat of the car before sitting on it… well, let’s just say it was easy to spot who just rode the bumper cars from behind, especially with white shorts on.

The properties that made graphite great for bumper cars — slippery, electrically conductive, tenacious, and cheap — are properties that make it a fit with innumerable industrial processes. The stuff turns up everywhere, and it’s becoming increasingly important as the decarbonization of transportation picks up pace. Graphite is amazingly useful stuff and fairly common, but not all that easy to extract and purify. So let’s take a look at what it takes to mine and refine graphite.

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USB-C For Hackers: Build Your Own PSU

October 12, 2023 by Arya Voronova 43 Comments

What if you wanted to build your own USB-C PSU? Good news – it’s easy enough! If you ever wanted to retrofit a decent DC PSU of yours to the USB-C standard, say, you got a Lenovo/HP/Dell 19V-20V charger brick and you’ve ever wished it were USB-C, today is the day when we do exactly that. To be fair, we will cheat a bit – but only a tiny bit, we won’t be deviating too much from the specification! And, to begin with, I’ll show you some exceptionally easy ways that you can turn your DC PSU into a USB-C compatible one, with a simple module or a few.

Turning a 20 V PSU into a USB-C PSU feels natural if you want to charge a laptop – those tend to request 20 V from a USB-C PSU anyway, so what’s the big deal? However, you can’t just put 20 V onto a USB-C connector – you have to add a fair bit of extra logic to make your newly christened USB-C PSU safe to use with 5 V devices, and this logic also requires you go through a few extra steps before 20 V appears on VBUS. Any USB-C PSU has to output 5 V first and foremost whenever a device is connected, up until a higher voltage is negotiated digitally, and the PSU may only switch to a higher voltage output when it’s requested to do so.

Now, for that, a PSU offers a list of profiles, and we looked into those profiles in the Replying PD article – each profile is four bytes that contain information about the profile voltage, maximum current that the device may draw at that voltage, and a few other details. For a PSU to be USB-C compliant, the USB-C specification says that, in addition to 5 V, you may also offer 9 V, 15 V, and 20 V.

Also, the specification says that if a PSU supports certain in-spec voltage like 15 V, it’s also required by the spec to offer all of the spec-defined voltages below the maximum one – for 15 V, that also requires supporting 9 V. Both of these are UX requirements, as opposed to technical requirements – it’s easier for device and PSU manufacturers to work with a small set of pre-defined voltages that majority of the chargers will support, but in reality, you can actually offer any voltage you want in the PSU advertisement; at worst, a device is going to refuse and contend with slowly charging from the 5 V output that you’re required to produce.

I’d like to walk you through how off-the-shelf USB-C PSUs work, all of the options you can use to to create one, and then, let’s build our own USB-C PSU from scratch! Continue reading “USB-C For Hackers: Build Your Own PSU” →

Tech In Plain Sight: Skyscrapers

October 11, 2023 by Al Williams 3 Comments

It is hard to imagine that for thousands of years, the Great Pyramid of Giza was the tallest manmade structure in the world. However, like the Lincoln Cathedral and the Washington Monument, which also held that title, these don’t count as skyscrapers because they didn’t provide living or working space to people. But aside from providing living, retail, or office space, skyscrapers also share a common feature that explains why they are even possible: steel frame construction.

Have you ever wondered why pyramids appear in so many ancient civilizations? The answer is engineering. You build something. Then, you build something on top of it. Then you repeat. It just makes sense. But each upper layer adds weight to all the lower layers, so you must keep getting smaller. Building a 381-meter skyscraper like the Empire State Building using self-supporting walls would mean the ground floor walls would be massive. Steel lets you get around this.

In Antiquity

You might think of high-rise buildings as a modern thing, but that’s actually not true. People seem to have built up to the best of their abilities for a very long time. Some Roman structures were as high as ten stories. Romans built so high that Augustus even tried to limit building height to 25 meters — probably after some accidents. In the 12th century, Bologna had as many as 100 towers, one nearly 100 meters tall.

There are many other examples, including mudbrick structures rising 30 meters in Yemen and 11th-century Egyptian structures rising 14 stories. In some cases, building up was due to the cost or availability of property. In others, it was to stay inside a defensive wall. But whatever the reason, self-supporting walls can only go so high before they are impractical.

So steel and iron frames grabbed the public’s attention with things like Joseph Paxton’s Crystal Palace in 1851, and Gustav Eiffel’s Tower in 1887.

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Robotic Mic Swarm Helps Pull Voices Out Of Crowded Room Of Multiple Speakers

October 4, 2023 by Lewin Day 27 Comments

One of the persistent challenges in audio technology has been distinguishing individual voices in a room full of chatter. In virtual meeting settings, the moderator can simply hit the mute button to focus on a single speaker. When there’s multiple people making noise in the same room, though, there’s no easy way to isolate a desired voice from the rest. But what if we ‘mute’ out these other boisterous talkers with technology?

Enter the University of Washington’s research team, who have developed a groundbreaking method to address this very challenge. Their innovation? A smart speaker equipped with self-deploying microphones that can zone in on individual speech patterns and locations, thanks to some clever algorithms.

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