Water is one of the most precious substances required to sustain human life. Unfortunately, in some areas like California, it’s starting to run out.
The ongoing drought has some people looking towards alternative solutions, such as sucking water out of the very air itself. In particular, a company called Tsunami Products has been making waves in the press with its atmospheric water generators, touting them as a solution for troubled drought-stricken areas, as reported by AP News. Today, we’ll look at how these machine capture water, and whether or not they can help in areas short on water.
The eyes are windows into the mind, and this research into what jumping spiders look at and why required a clever device that performs eye tracking, but for jumping spiders. The eyesight of these fascinating creatures in some ways has a lot in common with humans. We both perceive a wide-angle region of lower visual fidelity, but are capable of directing our attention to areas of interest within that to see greater detail. Researchers have been able to perform eye-tracking on jumping spiders, literally showing exactly where they are looking in real-time, with the help of a custom device that works a little bit like a miniature movie theatre.
A harmless temporary adhesive on top (and a foam ball for a perch) holds a spider in front of a micro movie projector and IR camera. Spiders were not harmed in the research.
To do this, researchers had to get clever. The unblinking lenses of a spider’s two front-facing primary eyes do not move. Instead, to look at different things, the cone-shaped inside of the eye is shifted around by muscles. This effectively pulls the retina around to point towards different areas of interest. Spiders, whose primary eyes have boomerang-shaped retinas, have an X-shaped region of higher-resolution vision that the spider directs as needed.
So how does the spider eye tracker work? The spider perches on a tiny foam ball and is attached — the help of a harmless and temporary adhesive based on beeswax — to a small bristle. In this way, the spider is held stably in front of a video screen without otherwise being restrained. The spider is shown home movies while an IR camera picks up the reflection of IR off the retinas inside the spider’s two primary eyes. By superimposing the IR reflection onto the displayed video, it becomes possible to literally see exactly where the spider is looking at any given moment. This is similar in some ways to how eye tracking is done for humans, which also uses IR, but watches the position of the pupil.
In the short video embedded below, if you look closely you can see the two retinas make an X-shape of a faintly lighter color than the rest of the background. Watch the spider find and focus on the silhouette of a tasty cricket, but when a dark oval appears and grows larger (as it would look if it were getting closer) the spider’s gaze quickly snaps over to the potential threat.
When it comes to weird and wacky homebrew rocket experiments, [Integza] keeps himself fairly busy. He’s now attempted a design repurposing Devil’s Toothpaste for propulsion.
Devil’s Toothpaste is really the same as the famous Elephant Toothpaste experiment, just executed with higher concentration hydrogen peroxide. In this case, [Integza] is using 50% hydrogen peroxide combined with potassium permanganate as a catalyst. When the two are combined, the hydrogen peroxide breaks down into oxygen and water, which [Integza] uses here to propel a skateboard.
The potassium permanganate catalyst is impregnated into 3D printed porous ceramic parts. The peroxide is then injected into this matrix via a compressed air mechanism, where it decomposes, creating a jet of water and oxygen that then blasts out of a 3D printed rocket nozzle to generate thrust.
It works surprisingly well, even if it’s a messy and unconventional way to build a rocket. It’s also a lot less fiery than most of [Integza]’s previous projects. Video after the break.
I recently started using a 50-year-old vacuum-seal flask that belonged to my Grandpa so that I don’t have to leave the dungeon as often to procure more caffeine. Besides looking totally awesome on my side desk, this thing still works like new, at least as far as I can tell — it’s older than I am.
Of course this got me to wondering how exactly vacuum-seal flasks, better known in household circles as Thermoses work, and how they were invented. The vacuum-seal flask is surprisingly old technology. It was first invented by Scottish chemist Sir James Dewar and presented to the Royal Institute in 1892. Six years later, he would be the first person to liquefy hydrogen and is considered a founding father of cryogenics. Continue reading “The Incredible Tech Of The Vacuum-Seal Flask”→
The average Hackaday user could probably piece together a rough model of a simple DC motor with what they’ve got kicking around the parts bin. We imagine some of you could even get a brushless one up and running without too much trouble. But what about an electrostatic corona motor? If your knowledge of turning high voltage into rotational energy is a bit rusty, let [Jay Bowles] show you the ropes in his latest Plasma Channel video.
Like many of his projects, this corona motor relies on a few sheets of acrylic, a handful of fasteners, and a healthy dose of physics. The actual construction and wiring of the motor is, if you’ll excuse the pun, shockingly simple. Of course part of that is due to the fact that the motor is only half the equation, you still need a high voltage source to get it running.
An earlier version of the motor ended up being too heavy.
In this case, [Jay] is revisiting his earlier experiments with atmospheric electricity to provide the necessary jolt. One side of the motor is connected to a metallic mesh electrode that’s carried 100 m into the air by a DJI Mini2 drone, while the other side is hooked up to several large nails driven into the ground.
The potential between the two gets the motor spinning, and makes for an impressive demonstration, but it’s not exactly the most practical way to experiment with your new corona motor. If you’d rather get it running on the workbench, he also shows that a more traditional high voltage source like a Van de Graaff generator will do the job nicely. As an added bonus, it can even power the device wirelessly from a few feet away.
So what can you do with a corona motor? While [Jay] is quick to explain that these sort of devices aren’t exactly known for their torque, he does show that his motor is able to lift a 45 gram weight suspended from a string. That’s frankly more power than we expected, and makes us wonder if there is some quasi-practical application for this contraption. If there is we suspect it’ll be featured in a future Plasma Channel video, so stay tuned.
When you’re standing at the gas station filling up your car, watching those digits on the pump flip by can be a sobering experience. Fuel prices, especially the price of gasoline, have always been keenly watched, so it’s hard to imagine a time when gasoline was a low-value waste product. But kerosene, sold mainly for lighting, was once king of the petroleum industry, at least before the automobile came along, to the extent that the gasoline produced while refining kerosene was simply dumped into streams to get rid of it.
The modern mind perhaps shudders at the thought of an environmental crime of that magnitude, and we can’t imagine how anyone would think that was a good solution to the problem. And yet we now face much the same problem, as the increasing electrification of the world’s fleet of motor vehicles pushes down gasoline demand. To understand why this is a problem, we’ll start off by taking a look at how crude oil is formed, and how decreasing demand for gasoline may actually cause problems that we should think about before we get too far down the road.
Even if you aren’t a giant history buff, you probably know that the French royal family had some difficulties in the late 1700s. The end of the story saw the King beheaded and, a bit later, his wife the famous Marie Antoinette suffered the same fate. Marie wrote many letters to her confidant, and probable lover, Swedish count Axel von Fersen. Some of those letters have survived to the present day — sort of. An unknown person saw fit to blot out parts of the surviving letters with ink, rendering them illegible. Well, that is, until now thanks to modern x-ray technology.
Anne Michelin from the French National Museum of Natural History and her colleagues were able to foil the censor and they even have a theory as to the ink blot’s origin: von Fersen, himself! The technique used may enable the recovery of other lost portions of historical documents and was published in the journal Science Advances.
