Animation In Education, 1950’s Style

Back before the days of computers, animation was drawn by hand. We typically think of cartoons and animated feature films, but there were other genres as well. For example, animation was also used in educational and training films. [Javier Anderson] has tracked down a series of antenna and RF training videos from the Royal Canadian Air Force in the 1950s and 60s and posted them on his YouTube channel.

He has found three of these gems, all on the topic of antenna fundamentals: propagation, directivity, and bandwidth (the film on propagation is linked below the break). Casually searching for the names listed in the film’s credits will lead you down an endless and fascinating rabbit hole about the history of Canadian animation and the formation of the Canadian National Film Board and its Studio A group of pioneering young artists (one can easily lose a couple of hours doing said searches, so be forewarned). For these films that [Javier] located, the animator is [Kaj Pindal]. [Kaj] (1927-2019) was a Dane who learned his craft as a teenager, drawing underground anti-Hitler comics in Copenhagen until fleeing for his life. He later emigrated to Canada, where he had a successful career as an artist and educator.

Animator [Kaj Pindal] at his desk, c.2012
Anyone who has tried to really grasp the physical connection between currents flowing in an antenna wire and the resultant radiated signal described by the second-order partial differential electromagnetic wave equation, all while using only a textbook, will certainly agree — unarguably this is a topic whose teaching can be significantly improved by animations such as [Kaj]’s. And if you’d like to sprinkle more phrases like “… in time-phase and space-quadrature …” into your conversations, then this film series is definitely for you.

Have you encountered any particularly helpful or well-made animated educational videos in your education and/or career? Are there any examples of similar but modern films made using computer generated images? Thanks to reader [Michael Murillo] for tipping us off to these old films.

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A Trio Of Photodiodes Make A Radiation Detector

The instinctive reaction when measuring nuclear radiation is to think of a Geiger counter, as the low-pressure gas tube detectors have entered our popular culture through the Cold War. A G-M tube is not the only game in town though, and even the humble photodiode can be pressed into service. [Robert] gives us a good example, with a self-contained radiation detector head that uses a trio of BPW34s to do the job.

At its heart is a transimpedance amplifier, a not-often-seen op-amp configuration that serves as a very high gain current-to-voltage converter. This produces a spike for every radiation event detected by the diodes, which is fed to a comparator to produce a logic pulse. The diodes require a significant bias voltage, for which he’s used 48 V from a stack of 12 V photographic dry cells rather than a boost converter or other potentially noisy power supply. Such a sensitive high-gain device needs to be appropriately shielded, so the whole circuit is contained in a diecast box with a foil window to allow radiation to reach the diodes.

This isn’t the first BPW34-based radiation detector we’ve seen, so perhaps before looking for a Cold War era relic for our radiation experiments we should be looking in a semiconductor catalogue instead.

3D Printing May Disprove Lord Kelvin

If you think 3D printing is only good for benchies, key chains, and printer parts, you might enjoy the paper by two physicists from Wesleyan University and the University of Gothenburg. Lord Kelvin — also known as William Thomson — hypothesized a shape known as an isotropic helicoid. As its name implies, the shape would look the same from any angle. Kelvin predicted that such a shape would spin as it sank in a liquid. Turns out, 3D printing proves it wrong. (The actual paywalled paper is available.)

It might seem strange that scientists are only now getting around to disproving a 150-year old hypothesis. However, the paper’s authors think Kelvin may have built the structures — he provided precise instructions — and simply dropped it when it proved incorrect.

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Levitation By Sound

Levitating things with magnets is no great feat these days. We don’t see as many projects with sonic levitation. However, Japanese engineers have a new method to lift objects using sound. The process isn’t totally reliable yet, but it may lead to better methods in the future. You can see a video about the work below.

Manipulating very small items via laser or acoustics isn’t new. However, there are significant limitations to current methods. This new approach uses an array of hemispherical ultrasound transducers. By controlling the amplitude and phase of each transducer, an acoustic trap forms and can pick up a 3 mm polystyrene ball without direct contact.

Manipulating objects without contact interests us for a few reasons, not the least of which is circuit assembly. Robust technology of this type could also add new dimensions to additive manufacturing. Of course, it is a long way from a 3 mm polystyrene ball to a surface mount component. However, you have to admit watching components just float through the air to their final resting places would be something to see.

Not that we haven’t seen sonic levitation before. Magnetic levitation tends to be easier, but also has some limitations.

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3D Printed Material Might Replace Kevlar

Prior to 1970, bulletproof vests were pretty iffy, with a history extending as far as the 1500s when there were attempts to make metal armor that was bulletproof. By the 20th century there was ballistic nylon, but it took kevlar to produce garments with real protection against projectile impact. Now a 3D printed nanomaterial might replace kevlar.

A group of scientists have published a paper that interconnected tetrakaidecahedrons made up of carbon struts that are arranged via two-photon lithography.

We know that tetrakaidecahedrons sound like a modern invention, but, in fact, they were proposed by Lord Kelvin in the 19th century as a shape that would allow things to be packed together with minimum surface area. Sometimes known as a Kelvin cell, the shape is used to model foam, among other things.

The 3D printing, in this case, is a form of lithography using precise lasers, so you probably won’t be making any of this on your Ender 3. However, the shape might have some other uses when applied to conventional 3D printing methods.

We’ve actually had an interest in the history of kevlar. Then again, kevlar isn’t the only game in town.

Liquid Nitrogen Isn’t Suitable For Steam Engines

Liquid nitrogen is fun stuff to play with, as long as you’re careful and avoid freezing your own fingers off and shattering them on the workbench. As the liquid turns to gaseous nitrogen at around -196 C, [The Action Lab] figured that it could be used to propel a simple steam engine at room temperature. Testing this out had amusing results.

The device under test is a Hero’s Engine, otherwise known as an aeolipile. This consists of a hollow sphere filled with water, fitted with a series of nozzles that shoot out steam when the vessel is heated. Via the rocket principle, this causes the device to rotate about its axis.

When filled with water and heated with a candle, the aeolipile spun at up to 2520 RPM. [The Action Lab] next tested it filled with water in a vacuum chamber, with the low pressure causing the water to boil at room temperature. The effect was less impressive however, with the engine spinning at a much slower rate.

The best result was with liquid nitrogen inside the engine. With the nitrogen quickly boiling at room temperature, the aeolipile quickly spun up to a great speed. The engine stand had to be steadied to avoid it tipping over, before the seal at the top of the engine blew off from overpressure.

We’d love to see the same experiment done with a piston-type steam engine, too. Video after the break.

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RNA Therapeutics And Fighting Diseases By Working With The Immune System

Before the SARS-CoV-2 pandemic took hold, few people were aware of the existence of mRNA vaccines. Yet after months of vaccinations from Moderna and BioNTech and clear indications of robust protection to millions of people, it now seems hard to imagine a world without mRNA vaccine technology, especially as more traditional vaccines seem to falter against the new COVID-19 variants and the ravages of so-called ‘Long COVID’ become more apparent.

Yet, it wasn’t that long ago that Moderna and BioNTech were merely a bunch of start-ups, trying to develop profitable therapies for a variety of diseases, using the brand-new and largely unproven field of RNA therapeutics. Although the use of mRNA in particular for treatments has been investigated since 1989, even as recently as 2017 there were still many questions about safe and effective ways to deliver mRNA into cells, as per Khalid A. Hajj et al.

Clearly those issues have been resolved now in 2021, which makes one wonder about the other exciting possibilities that mRNA delivery offers, from vaccines for malaria, cancer, HIV, as well as curing autoimmune diseases. How did the field of mRNA vaccines develop so quickly, and what can we expect to see the coming years?

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