Science

1288 Articles

Filming The Eclipse From 80,000 Feet

May 22, 2024 by 4 Comments

Watching an eclipse from the ground is pretty fun. Depending on where you live, you might even get a decent view. But what if you wanted a truly unique vantage point? You could replicate the work of [Tarik Agcayazi] and [kemfic], who set about filming the recent eclipse from an altitude of 80,000 feet.

That’s what the eclipse looks like from 80,000 feet.

The duo didn’t rent a high-performance aircraft from the US military. Instead, they relied on a high-altitude balloon carrying a glider with a camera payload. The idea was for the balloon to go up, and have the camera capture the eclipse. Then, it would be released so that it could glide back home in controlled flight. However, time constraints made that too hard. Instead, they simplified to a parachute recovery method.

The project video covers the development process, the balloon launch itself, and of course, the filming of the eclipse. High altitude balloon launches are stressful enough, but having a short eclipse as a target made everything even more difficult. But that just makes things more exciting!

The project builds on earlier work from the duo that we discussed back in 2017.

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Peeking Underground With Giant Flying Antennas

May 21, 2024 by 21 Comments

Helicopters are perhaps at their coolest when they’re being used as flying cranes — from a long dangling cable, they can carry everything from cars, to crates, to giant hanging saws.

What you might find altogether more curious are the helicopters that fly around carrying gigantic flat antenna arrays. When you spot one in the field, it’s not exactly intuitive to figure out what they’re doing, but these helicopters are tasked with important geological work!

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Möbius String Robot Goes Round And Round

May 19, 2024 by 9 Comments

While it doesn’t look like a traditional robot, the hydrogel robot from [Zi Liang Wu] forms a möbius strip and can be activated by light. They also experimented with shaping the hydrogels as a Seifert ribbon.

The key is that the hydrogels contain gold nanoparticles. Light heats the gold particles and this causes the hydrogels to move. The connections between the strips of hydrogels causes them to move in predictable ways. You can see a video about the experiments below.

These robots aren’t going to be for warehouse or factory work. But they can do tasks like collecting plastic beads, something difficult for conventional robots to do. They also hope to demonstrate that these soft robots could work in the body for taking samples or delivering a drug, although it isn’t apparent how light would get to them inside your body.

The dark side of the material tends to turn towards the light. The continuous loop structure means it never runs to the end of its travel. Watching it move on a string is pretty impressive.

Crawling and slithering robots may be the answer for certain specialized applications. After all, it works well in nature.

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Nature Vs Nurture In Beethoven’s Genome

May 17, 2024 by 19 Comments

When it comes to famous musicians, Beethoven is likely to hit most top ten charts. Researchers recently peered into his genome to see if they could predict his talent by DNA alone.

Using a previously-identified polygenetic index (PGI) for musical talent, which finds the propensity of certain genes to influence a given trait after a genome-wide association study (GWAS), the researchers were able to compare samples of Beethoven’s DNA to that of two separate population studies with known musical achievement data.

Much to the relief of those who saw Gattaca as a cautionary tale, the scientists found that Beethoven scored only around the tenth percentile for the ability to keep a beat according to his genetic markers. According to the researchers, using genetic markers to predict abilities of an individual can lead to incorrect conclusions, despite their usefulness for group level analyses.

Curious about more musical science? How about reconstructing “Another Brick in The Wall (Part I)” from brainwaves or building a Square Laser Harp?

Is The Frequency Domain A Real Place?

May 16, 2024 by 60 Comments

When analyzing data, one can use a variety of transformations on the data to massage it into a form that works better to tease out the information one is interested in. One such example is the application of the Fourier transform, which transforms a data set from the time domain into the frequency domain. Yet what is this frequency domain really? After enticing us to follow the white rabbit down a sudden plummet into the intangible question of what is and what is not, [lcamtuf] shows us around aspects of the frequency domain and kin.

One thing about the (discrete) Fourier transform is that it is excellent at analyzing data that consists out of sinewaves, such as audio signals. Yet when using the Fourier transform for square waves, the resulting output is less than useful, almost as if square waves are not real. Similarly, other transforms exist which work great for square waves, but turn everything else into meaningless harmonics. Starting with the discrete cosine transform (DCT), this gets us into Walsh and Hadamard matrices and the Walsh-Hadamard Transform (WHT), and their usage with transforming data from the time into the frequency domain.

Ultimately it would seem that the frequency domain is as real as it needs to be, albeit that its appearance is wholly dependent on the algorithm used to create it, whether this the DFT, DCT, WHT or something else entirely.

Introduction To MOSFET Switching Losses

May 15, 2024 by 17 Comments

Metal-oxide semiconductor field-effect transistors (MOSFETs) see common use in applications ranging from the very small (like CPU transistors) to very large (power) switching applications. Although its main advantage is its high power efficiency, MOSFETs are not ideal switches with a perfect on or off state. Understanding the three main sources of switching losses is crucial when designing with MOSFETs, with a recent All About Circuits article by [Robert Keim] providing a primer on the subject.

As it’s a primer, the subthreshold mode of MOSFET modes of operation is omitted, leaving the focus on the linear (ohmic) mode where the MOSFET’s drain-source is conducting, but with a resistance that’s determined by the gate voltage. In the saturated mode the drain-source resistance is relatively minor (though still relevant), but the turn-on time (RDS(on)) before this mode is reached is where major switching losses occur. Simply switching faster is not a solution, as driving the gate incurs its own losses, leaving the circuit designer to carefully balance the properties of the MOSFET.

For those interested in a more in-depth study of MOSFETs in e.g. power supplies, there are many articles on the subject, such as this article (PDF) from Texas Instruments.

The Great Green Wall: Africa’s Ambitious Attempt To Fight Desertification

May 9, 2024 by 61 Comments

As our climate changes, we fear that warmer temperatures and drier conditions could make life hard for us. In most locations, it’s a future concern that feels uncomfortably near, but for some locations, it’s already very real. Take the Sahara desert, for example, and the degraded landscapes to the south in the Sahel. These arid regions are so dry that they struggle to support life at all, and temperatures there are rising faster than almost anywhere else on the planet.

In the face of this escalating threat, one of the most visionary initiatives underway is the Great Green Wall of Africa. It’s a mega-sized project that aims to restore life to barren terrain.

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