This Machine Learning Algorithm Is Meta

September 3, 2019 by Bryan Cockfield 20 Comments

Suppose you ran a website releasing many articles per day about various topics, all following a general theme. And suppose that your website allowed for a comments section for discussion on those topics. Unless you are brand new to the Internet, you’ll also imagine that the comments section needs at least a little bit of moderation to filter out spam, off topic, or even toxic comments. If you don’t want to employ any people for this task, you could try this machine learning algorithm instead.

[Ladvien] goes through a general overview of how to set up a convolutional neural network (CNN) which can be programmed to do many things, but this one crawls a web page, gathers data, and also makes decisions regarding that data. In this case, the task is to identify toxic comments but the goal is not to achieve the sharpest sword in the comment moderator’s armory, but to learn more about how CNNs work.

Written in Python, the process outlines the code itself and how it behaves, setting up a small server to host the neural network, and finally creating the webservice. As with any machine learning, you need a reliable dataset to use for training and this one came from Wikipedia comments previously flagged by humans. Trolling nuance is thrown aside, as the example homes in on blatant insults and vulgarity.

While [Ladvien] notes that his guide isn’t meant to be comprehensive, but rather to fill in some gaps that he noticed within other guides like this, we find this to be an interesting read. He also mentioned that, in theory, this tool could be used to predict the number of comments following an article like this very one based on the language in the article. We’ll leave that one as an academic exercise for now, probably.

3D Printing May Be The Key To Practical Scramjets

September 3, 2019 by Tom Nardi 32 Comments

The first scramjet, an airbreathing jet engine capable of pushing an aircraft beyond Mach 5, was successfully flown in the early 1990s. But while pretty much any other technology you could imagine has progressed by leaps and bounds in the nearly 30 years that have passed, the state-of-the-art in hypersonic scramjets hasn’t moved much. We still don’t have practical hypersonic aircraft, military or otherwise, and any missiles that travel at those sort of speeds are rocket powered.

This is somewhat surprising since, at least on paper, the operating principle of the scramjet is simplicity itself. Air rushing into the engine is compressed by the geometry of the inlet, fuel is added, the mixture is ignited, and the resulting flow of expanded gases leaves the engine faster than it entered. There aren’t even any moving parts inside of a scramjet, it’s little more than a carefully shaped tube with fuel injectors and ignitors in it.

Unfortunately, pulling it off in practice is quite a bit harder. Part of the problem is that a scramjet doesn’t actually start working until the air entering the engine’s inlet is moving at around Mach 4, which makes testing them difficult and expensive. It’s possible to do it in a specially designed wind tunnel, but practically speaking, it ends up being easier to mount the engine to the front of a conventional rocket and get it up to speed that way. The downside is that such flights are one-way tickets, and end with the test article crashing into the ocean once it runs out of fuel.

But the bigger problem is that the core concept is deceptively simple. It’s easy to say you’ll just squirt some jet fuel into the stream of compressed air and light it up, but when that air is moving at thousands of miles per hour, keeping it burning is no small feat. Because of this, the operation of a scramjet has often been likened to trying to light a match in a hurricane; the challenge isn’t in the task, but in the environment you’re trying to perform it in.

Now, both Aerojet Rocketdyne and Northrop Grumman think they may have found the solution: additive manufacturing. By 3D printing their scramjet engines, they can not only iterate through design revisions faster, but produce them far cheaper than they’ve been able to in the past. Even more importantly, it enables complex internal engine geometries that would have been more difficult to produce via traditional manufacturing.

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Null Shard Build Blurs Line Between Game And Reality With Laser Cutting, Mold Making, 3D Printing

September 3, 2019 by Tom Nardi 7 Comments

In The Room Three, players are tasked with collecting mysterious objects known as “Null Shards”. But it seems one player, who goes by the name [Juiceman], took this challenge a bit literally. Starting with promotional art released for the game, he embarked on an epic journey to create a replica “Null Shard” that ended up looking so good that one of them is currently residing in a place of honor at the headquarters of developer Fireproof Games.

The developers had previously released image files to create a papercraft version of the Null Shard on their website, so [Juiceman] based his initial CAD work on these designs. But it turned out the surface texture was a little too complex to laser etch into acrylic without making a soupy mess. He simplified it a bit, while trying to retain the overall effect. From the superb laser-etched acrylic master he made a silicone mold started casting the eight triangular panels needed for two copies of the Shard.

To hold it all together [Juiceman] create a “skeleton” pyramid by first experimenting with designs on a traditional plastic FDM printer. After a few tries he had a workable design and switched over to a laser sintering machine, giving the final frame a gorgeous texture. With the cast panels installed and a few coats of paint, he had his Null Shards.

The final step was to turn down a piece of ash to make a nice base, and 3D print the feet and “claw” mount for the Shard using the same laser sintering process. The finished product looks fantastic, and apparently lives on a shelf next to a similarly constructed replica of the “Lament Configuration” puzzle cube from the Hellraiser films. [Juiceman] says the two replicas are the first entries into his “Geometries of Hell” collection, which incidentally, we’ve decided will officially be the name of our first metal album. All we need to do now is learn how to play instruments.

We’ve previously looked at how 3D printing and a dash of dedication can create some incredible prop builds, and once upon a time, we even ran a Sci-Fi Contest that challenged our readers to bring their favorite movie and game objects into the real world. Builds like this are a perfect example of what happens when a dedicated hacker or maker gets inspired by a piece of entertainment that really resonates with them.

[Thanks to Lauren for the tip]

Ham Radio Gets Embedded RTL-SDR

September 3, 2019 by Tom Nardi 13 Comments

We usually think of the RTL-SDR as a low-cost alternative to a “real” radio, but this incredible project spearheaded by [Rodrigo Freire] shows that the two classes of devices don’t have to be mutually exclusive. After nearly 6 months of work, he’s developed and documented a method to integrate a RTL-SDR Blog V3 receiver directly into the Yaesu FT-991 transceiver.

The professional results of the hack are made possible by the fact that the FT-991 already had USB capability to begin with. More specifically, it had an internal USB hub that allowed multiple internal devices to appear to the computer as a sort of composite device.

Unfortunately, the internal USB hub only supported two devices, so the first order of business for [Rodrigo] was swapping out the original USB2512BI hub IC with a USB2514BI that offered four ports. With the swap complete, he was able to hang the RTL-SDR device right on the new chip’s pins.

Of course, that was only half of the battle. He had a nicely integrated RTL-SDR from an external standpoint, but to actually be useful, the SDR would need to tap into the radio’s signal. To do this, [Rodrigo] designed a custom PCB that pulls the IF signal from the radio, feed it into an amplifier, and ultimately pass it to the SDR. The board uses onboard switches, controlled by the GPIO ports on the RTL-SDR Blog V3, for enabling the tap and preamplifier.

In the video after the break, you can see [Rodrigo] demonstrate his modified FT-991. This actually isn’t the first time somebody has tapped into their Yaesu with a software defined radio, though this is surely the cleanest install we’ve ever seen.

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