Sleep apnea is a debilitating disease that many sufferers don’t even realize they have. Those afflicted with the condition will regularly stop breathing during sleep as the muscles in their throat relax, sometimes hundreds of times a night. Breathing eventually resumes when the individual’s oxygen supply gets critically low, and the body semi-wakes to restore proper respiration. The disruption to sleep causes serious fatigue and a wide range of other deleterious health effects.
Treatment for sleep apnea has traditionally involved pressurized respiration aids, mechanical devices, or invasive surgeries. However, researchers are now attempting to develop a new drug combination that could solve the problem with pharmaceuticals alone.
There’s little about building spacecraft that anyone would call simple. But there’s at least one element of designing a vehicle that will operate outside the Earth’s atmosphere that’s fairly easier to handle: aerodynamics. That’s because, at the altitude that most satellites operate at, drag can essentially be ignored. Which is why most satellites look like refrigerators with solar panels and high-gain antennas attached jutting out at odd angles.
But for all the advantages that the lack of meaningful drag on a vehicle has, there’s at least one big potential downside. If a spacecraft is orbiting high enough over the Earth that the impact of atmospheric drag is negligible, then the only way that vehicle is coming back down in a reasonable amount of time is if it has the means to reduce its own velocity. Otherwise, it could be stuck in orbit for decades. At a high enough orbit, it could essentially stay up forever.
Launched in 1958, Vanguard 1 is expected to remain in orbit until at least 2198
There was a time when that kind of thing wasn’t a problem. It was just enough to get into space in the first place, and little thought was given to what was going to happen in five or ten years down the road. But today, low Earth orbit is getting crowded. As the cost of launching something into space continues to drop, multiple companies are either planning or actively building their own satellite constellations comprised of thousands of individual spacecraft.
Fortunately, there may be a simple solution to this problem. By putting a satellite into what’s known as a very low Earth orbit (VLEO), a spacecraft will experience enough drag that maintaining its velocity requires constantly firing its thrusters. Naturally this presents its own technical challenges, but the upside is that such an orbit is essentially self-cleaning — should the craft’s propulsion fail, it would fall out of orbit and burn up in months or even weeks. As an added bonus, operating at a lower altitude has other practical advantages, such as allowing for lower latency communication.
VLEO satellites hold considerable promise, but successfully operating in this unique environment requires certain design considerations. The result are vehicles that look less like the flying refrigerators we’re used to, with a hybrid design that features the sort of aerodynamic considerations more commonly found on aircraft.
When you’re driving a car with a stickshift, it’s pretty easy to keep track of which gear you’re in. That can be a little bit more difficult on something like a motorcycle with a sequential shifter. [decogabry] built a neat gearshift indicator to solve this issue.
An ESP32 devboard is used as the brain of the build. It’s paired with an ELM327 dongle over Bluetooth, which is able to hook into the bike’s ODB diagnostic port to pick up data like engine RPM, wheel speed, and coolant temperature. The first two factors are combined in order to calculate the current gear, since the ratio between engine RPM and wheel speed is determined directly by the gear selection. The ESP32 then commands a Philips ZM1020 Nixie tube to display the gear, driving it via a small nest of MPSA42 transistors. A separate self-contained power supply module is used to take the bike’s 12 volt supply up to the 170 volts needed to run the tube. There is also a small four-digit display used to show status information, RPM, and engine temperature.
Notably, [decogabry] made this build rather flexible, to suit any bike it might be installed upon. The gear ratios are not hard coded in software. Instead, there is a simple learning routine that runs the first time the system is powered up, which compares RPM and wheel speed during a steady-state ride and saves the ratios to flash.
We’ve featured projects before that used different techniques to achieve similar ends. It’s also interesting to speculate as to whether there’s a motorcycle vintage enough to suit a Nixie display while still having an ODB interface on board as standard. Meanwhile, if you’re cooking up your own neat automotive builds, don’t hesitate to drop us a line.
If you ever built a line following robot, you’ll be nostalgic about [Jeremy’s] light-seeking robot. It is a very simple build since there is no CPU and, therefore, also no software.
The trick, of course, is a pair of photo-sensitive resistors. A pair of motors turns the robot until one of the sensors detects light, then moves it forward.
Get a handle on this bad boy! Okay, so those voids are really more for airing out your palms, I’d imagine, because palm sweat sure is real — you should see the pads of my Kinesis. This kind of looks like two sawed-off machine guns kissing, and I mean that in the best possible and non-violent way.
Image by [ntc490] via redditSo, [ntc490] has been on Team Special Keyboard for eight years now and decided it was time to design one. The goal was to make something semi-portable, super ergo, and as easy/cheap to build as possible, which, honestly, that sounds like one of those pick-two situations.
And yet, pricing (oh yeah, this is gonna be A Thing You Can Buy) will be around $115-155, depending upon whether you want the base kit, or the add-ons, too, minus switches and key caps.
So let’s get into the particulars here. As you can see, there are key wells and thumb clusters, inspired by other keyboards including your bog standard Maltrons, Kinesis Advantages and more modern, open-source takes like the Dactyl. [ntc490] loves the key well-thumb cluster combination, and I do, too (hello from the Glove80). And miraculously, the keys are hot-swappable via sockets.
Image by [ntc490] via redditThat novel tenting mechanism is adjustable, rugged, and portable. You can tent it near-vertical, lay it flat, or take it apart if you wish. The thing is modular for future expansion options such as wrist rests and displays.
So please do go visit the thread if this keyboard appeals to you at this price point. I love it, but I would need more rows of keys, personally. The top reddit comment mentions this as well, and [ntc490] says that because the thing is modular, it can easily accommodate more keys in both the wells and the thumb clusters. I seriously want one of these. Just with a few more keys.
There’s an adage coined by [Ian Betteridge] that any headline ending in a question mark can be answered by the word “No”. However, Lorentz invariance – the theory that the same rules of physics apply in the same way in all frames of reference, and an essential component of special relativity – has been questioned for some time by researchers trying to unify general relativity and quantum field theory into a theory of quantum gravity. Many theories of quantum gravity break Lorentz invariance by giving photons with different energy levels very slightly different speeds of light – a prediction which now looks less likely since researchers recently analyzed gamma ray data from pulsed astronomical sources, and found no evidence of speed variation (open-access paper).
The researchers specifically looked for the invariance violations predicted by the Standard-Model Extension (SME), an effective field theory that unifies special relativity with the Standard Model. The variations in light speed which it predicts are too small to measure directly, so instead, the researchers analyzed gamma ray flare data collected from pulsars, active galactic nuclei, and gamma-ray bursts (only sources that emitted gamma rays in simultaneous pulses could be used). Over such great distances as these photons had traveled, even slight differences in speed between photons with different energy levels should have added up to a detectable delay between photons, but none was found.
This work doesn’t disprove the SME, but it does place stricter bounds on the Lorentz invariance violations it allows, about one and a half orders of magnitude stricter than those previously found. This study also provides a method for new experimental data to be more easily integrated into the SME. Fair warning to anyone reading the paper: the authors call their work “straightforward,” from which we can only conclude that the word takes on a new meaning after a few years studying mathematics.
I’m not proud. When many of us were kids, we were unabashedly excited when trash day came around because sometimes you’d find an old radio or — jackpot — an old TV out by the curb. Then, depending on its size, you rescued it, or you had your friends help, or, in extreme cases, you had to ask your dad. In those days, people were frugal, so the chances of what you found being fixable were slim to none. If it was worth fixing, the people would have probably fixed it.
While TVs and radios were the favorites, you might have found other old stuff, but in those days, no one was throwing out a computer (at least not in a neighborhood), and white goods like refrigerators and washing machines had very little electronics. Maybe a mechanical timer or a relay, but that’s about it.
