Author: Navarre Bartz

306 Articles

A black quadcopter sits on a grey surface. In place of traditional propellers are four figure eight propellers with sharp tips where the top and bottom of the eight would be.

Toroidal Propellers Make Drones Less Annoying

January 28, 2023 by 61 Comments

Despite being integral to aviation for more than a century, propellers have changed remarkably little since the Wright Brothers. A team at MIT’s Lincoln Lab has developed a new propeller shape that significantly reduces the noise associated with drones. [PDF via NewAtlas]

Inspired by some of the experiments with “ring wings” in the early 20th Century, researchers iterated on various toroidal propeller geometries until arriving at one that significantly reduces the sound produced by the rotors, particularly in the range of human hearing. The team suspects the reduction in noise is due to vortices being distributed over the whole propeller instead of just the tips.

Experiments show the drones can get twice as close before becoming a nuisance for human ears which should be great news for anyone hoping to launch Skynet commercial drone deliveries. Since the rotors are easily fabricated via 3D printing they should be easy to adapt to a number of different drones.

If you want to explore some more interesting drones, checkout this one that can fly and swim or this one that only uses a single propeller.

Four images in one. Top left is an image of four individuals in a room with whiteboards and desks in the background along with various clutter on the floor. Over the people is a wireframe overlay of their poses. The image on the top right is just the wireframe people on a black background. Bottom left image is of a single individual standing in a room with the pose wireframe overlay. Bottom right image is the single pose wireframe on a black background.

Tracking Humans With WiFi

January 26, 2023 by 45 Comments

In case you thought that cameras, LiDAR, infrared sensors, and the like weren’t enough for Big Brother to track you, researchers from Carnegie Mellon University have found a way to track human movements via WiFi. [PDF via VPNoverview]

The process uses the signals from WiFi routers for an inexpensive way to determine human poses that isn’t hampered by lack of illumination or object occlusion. The system produces UV coordinates of human bodies by analyzing signal strength and phase data to generate a 2D feature map and then feeding that through a modified DensePose-RCNN architecture which corresponds to 3D human poses. The system does have trouble with unusual poses that are not in the training set or if there are more than three subjects in the detection area.

While there are probably applications in Kinect-esque VR Halo games, this will probably go straight into the toolbox of three letter agencies and advertising-fueled tech companies. The authors claim this to use “privacy-preserving algorithms for human sensing,” but only time will tell if they’re correct.

If you’re interested in other creepy surveillance tools, checkout the Heat-Sensing Crotch Monitor or this Dystopian Peep Show.

A woman sits at a wooden table with a set of pedals attached. A large frame sits on top of the table with a lampshade form spinning in it and five strings run through an apparatus to the frame. A shelving unit with finished lampshades sits behind the woman.

Lanna Factory Makes You Work For Your Lampshade

January 24, 2023 by 6 Comments

While you could 3D print a lampshade, there’s something to be said for having a more active role in the process of creating an object. [THINKK Studio] has made custom lampshades as easy as riding a bike.

The Lanna Factory was inspired by the cotton ball string lamps sold by vendors in Thai flea markets. Bangkok-based [THINKK Studio] wanted to build a device to let anyone have a hand (and feet) in making a custom lampshade without any experience. Five spools of thread are routed through a “glue case” and onto a spindle holding a lampshade mold. Pedals control the wrapping speed and the location on the shade being wrapped is controlled with a hand wheel on the table.

Once the glue dries, the shade can be removed from the mold and fitted with the appropriate hardware. Giving the user control over the process means that each lampshade will be unique and the final product will mean that much more to the person who made it.

If you’re thinking this would be cooler in carbon fiber, than maybe you should checkout the X-Winder.

Continue reading “Lanna Factory Makes You Work For Your Lampshade” →

A cartoon vehicle is connected to two wires. One is connected to an illustrated Li anode and the other to a γ-sulfur/carbon nanofiber electrode. Lithium ions and organic carbonate representations float between the two electrodes below the car. A red dotted line between the electrodes symbolizes the separator.

Lithium Sulfur Battery Cycle Life Gets A Boost

January 24, 2023 by 11 Comments

Lithium sulfur batteries are often touted as the next major chemistry for electric vehicle applications, if only their cycle life wasn’t so short. But that might be changing soon, as a group of researchers at Drexel University has developed a sulfur cathode capable of more than 4000 cycles.

Most research into the Li-S couple has used volatile ether electrolytes which severely limit the possible commercialization of the technology. The team at Drexel was able to use a carbonate electrolyte like those already well-explored for more traditional Li-ion cells by using a stabilized monoclinic γ-sulfur deposited on carbon nanofibers.

The process to create these cathodes appears less finicky than previous methods that required tight control of the porosity of the carbon host and also increases the amount of active material in the cathode by a significant margin. Analysis shows that this phase of sulfur avoids the formation of intermediate fouling polysulfides which accounts for it’s impressive cycle life. As the authors state, this is far from a commercial-ready system, but it is a major step toward the next generation of batteries.

We’ve covered the elements lithium and sulfur in depth before as well as an aluminum sulfur battery that could be big for grid storage.

A white clock with a house profile sits on a variegated grey background. A yellow skein of yarn sits on the top left side of the clock feeding into a circular loom that takes up the bulk of the center. A yellow scarf extends out the back of the clock and out of frame below the image.

Knitting Clock Makes You A Scarf For Next Year

January 23, 2023 by 17 Comments

Time got a little wibbly wobbly during these pandemic years. Perhaps we would’ve had a more tangible connection to it if [Siren Elise Wilhelmsen]’s knitting clock had been in our living rooms.

Over the course of a year, [Wilhelmsen]’s clock can stitch a two meter scarf by performing a stitch every half hour. She says, “Time is an ever forward-moving force and I wanted to make a clock based on times true nature, more than the numbers we have attached to it.” Making the invisible visible isn’t always an easy feat, but seeing a clock grow a scarf is reminiscent of cartoon characters growing a beard to organically communicate the passage of time.

We’d love some more details about the knitting machine itself, but that seems like it wasn’t the focus of the project. A very small run of these along with a couple prototypes were built, with a knitting grandfather clock now occupying the lobby of The Thief hotel in Oslo.

If you’re looking for more knitting machines, checkout this Knitting Machine Rebuild or Knitting 3D Models Into Stuffies.

Continue reading “Knitting Clock Makes You A Scarf For Next Year” →

A four-fingered partial hand prosthesis in fuschia with black fingerpads is attached to a man's left hand (palm and thumb are original). He holds the left hand + prosthetic with his right hand and an aluminum hand prosthetic sits on the table to the left of his hands.

Designing A Simpler Prosthetic Finger

January 22, 2023 by 5 Comments

Prosthetic limb design is an area where desktop manufacturing has made huge strides, but there’s always room for improvement. For example, take a look at [Ian Davis] and his attempts to design a simpler prosthetic finger.

[Davis] favors his aluminum partial hand prosthetic for its strength, but because it was scratch built for his particular situation, it isn’t easy to recreate for someone else. To this end, he has started working on a simpler design that might be applicable in the future for people who want to build their own prosthetics. With less than ten major components per finger including the replaceable TPU fingerpads, this is a major step toward that end.

According to [Davis], one of the more exciting parts of the build is that while this hand has a more limited feature set, he was able to get it closer to the size of his natural hand. Because of the durability problems he’s experienced for day-to-day use of plastic prosthetics, he is having the next iteration 3D printed in stainless steel for further testing.

If you want to see some more interesting prosthetic designs, checkout the Kid Who Designed His Own Prosthetic Arm or this Skull Lamp Prosthetic Eye.

An illustration of a key sitting on an ID card. The key is light grey and the ID card is a darker grey gradient. The ID card says ID-1 Card 85.60 by 53.98 mm

All Your Keys Are Belong To KeyDecoder

January 21, 2023 by 56 Comments

Physical security is often considered simpler than digital security since safes are heavy and physical keys take more effort to duplicate than those of the digital persuasion. [Maxime Beasse and Quentin Clement] have developed a smartphone app that can duplicate a key from a photo making key copying much easier.

KeyDecoder is an open source Android app that can generate all the necessary bitting info to duplicate a key from just an image. Luckily for the paranoid among us, the image must be taken with the key laying flat without a keyring on an ISO/CEI 7810 ID-1 ID or credit card. A passerby can’t just snap a photo of your keys across the room and go liberate your home furnishings, but it still would be wise to keep a closer eye on your keys now that this particular cat hack is out of the bag.

The project’s GitHub page is awash in warnings that this tool is designed solely for “pentesters and security enthusiasts” to warn their friends and clients about the dangers of leaving their keys exposed. After learning about this tool, we wouldn’t be surprised if some in the audience start rethinking how they carry and store their physical keys from now on.

If you want to see some more hacks to duplicate keys, checkout Copying High Security Keys With OpenSCAD And Light and Methods Of Copying High Security Keys.