Gravity can be a difficult thing to simulate effectively on a traditional CPU. The amount of calculation required increases exponentially with the number of particles in the simulation. This is an application perfect for parallel processing.
For their final project in ECE5760 at Cornell, [Mark Eiding] and [Brian Curless] decided to use an FPGA to rapidly process gravitational calculations. This allows them to simulate a thousand particles at up to 10 frames per second. With every particle having an attraction to every other, this works out to an astonishing 1 million inverse-square calculations per frame!
The team used an Altera DE2-115 development board to build the project. General operation is run by a Nios II processor, which handles the VGA display, loads initial conditions and controls memory. The FPGA is used as an accelerator for the gravity calculations, and lends the additional benefit of requiring less memory access operations as it runs all operations in parallel.
This project is a great example of how FPGAs can be used to create serious processing muscle for massively parallel tasks. Check out this great article on sorting with FPGAs that delves deeper into the subject. Video after the break.
Continue reading “Gravity Simulations With An FPGA”
[Bigelow Brook Farm] has a cool geodesic dome greenhouse that needs to stay warm in the winter. There are a lot of commercial solutions for greenhouse heating, but if you’re the kind of person who research and develops solutions for aquaponics, a greener solution may have more appeal.
A rocket mass heater is a combination of a rocket stove and underfloor heating. A rocket stove works by having such a strong draft created by the heat rising up the chimney that the flames can’t crawl up the fuel and burn in the open air, creating a controlled burn zone. Unfortunately, with just a plain rocket stove a lot of heat is lost to the atmosphere needlessly. You only need enough to create the draft.
The mass part solves this. It runs the exhaust under the floor and through radiators. This passively retains a lot of heat inside the space to be heated. It’s a bit of a trick to balance the system so it puts as much heat into the space as possible without stalling, which can be dangerous due to carbon monoxide, among other things. Once the balance is achieved the user gets a stove that can burn fuel very effectively and best of all passively.
[Bigelow Brook Farms] have been working on their heater for quite some time. We really enjoy their test driven development and iteration. They have really interesting autopsies when a component of the heater fails and needs replacing. Right now they have a commercial sized operation heated by their latest iteration and it’s completely passive, being gravity fed. Video after the break.
Continue reading “DIY Rocket Mass Heater Build Log For Commercial Greenhouse”
When you hear “gravity waves” or “sprites”, you’d think you would know what is being discussed. After all, those ripples in space-time that Einstein predicted would emanate from twin, colliding, black holes were recently observed to much fanfare. And who doesn’t love early 8-bit computer animations? So when we were browsing over at SpaceWeather we were shocked to find that we were wrong twice, in one photo (on the right). Continue reading “Two Words That Don’t Mean What You Think They Do”
It was the year of 1687 when Isaac Newton published “The Principia“, which revealed the first mathematical description of gravity. Newton’s laws of motion along with his description of gravity laid before the world a revolutionary concept that could be used to describe everything from the motions of heavenly bodies to a falling apple. Newton would remain the unequivocal king of gravity for the next several hundred years. But that would all change at the dawn of the 20th century when a young man working at a Swiss patent office began to ask some profound questions. Einstein had come to the conclusion that Newtonian physics was not adequate to describe the findings of the emerging electromagnetic field theories. In 1905, he published a paper entitled “On the Electrodynamics of Moving Bodies” which corrects Newton’s laws so they work when describing the motions of objects near the speed of light. This new description became known as Special Relativity.
It was ‘Special’ because it didn’t deal with gravity or acceleration. It would take Einstein another 10 years to work these two concepts into his relativity theory. He called it General Relativity – an understanding of which is necessary to fully grasp the significance of gravitational waves.
Continue reading “About Those Gravitational Waves”
You thought we forgot about your favorite Hackaday comment game, didn’t you? Well, not only is ‘Real or Fake?’ back with a new installment, but this time it concerns everybody’s favorite impossibility: perpetual motion machines! It’s likely that you’ve already seen the photos of Brazilian energy group RAR Energia’s generator “powered exclusively by gravity” (translated). If you’re rolling your eyes and exclaiming “this is so last year..” you might want to scroll down to the bottom of the page; they’re still building this monstrosity and they’ve included some diagram images. Perhaps someone who reads Portuguese can better translate the claim that the devices are “demonstration models with capacity to generate 30kW.” Oh, didn’t you know? There are two of them now: one in Brazil that is presumably functioning, and a second under construction in Gilman, Illinois.
Now, before you all scream “Photoshopped,” take a gander at a FotoForensics analysis of one of the images, where ELA (error level analysis) seems to indicate consistent levels of compression. EXIF data shows the pictures were shot with a Sony DSC-WX5 and saved in PhotoScape. It may be simpler than that: you can easily recognize the same employees in different shots from different angles, and there are quite a lot of photos. RAR Energia’s most recent endeavor—a second machine in Gilman Illinois—seems to have been erected in the past two months. The Gilman warehouse is located on property belonging to bio-diesel manufacturing firm Incobrasa Industries (named a “Company of the [RAR Energia] group” on the RAR Energia site). Here’s a little internet sleuthing for your consideration: a photo of the completed warehouse and a Google maps link to the location in question (40.763176, -88.012706). Note the distinctly shaped building in the background (another view here, during construction), which can be found due south of the location indicated in the Google maps link. We’re not suggesting that you completely rule out image manipulation, but if it’s Photoshopped, it’s a damned elaborate job.
Unfortunately, there aren’t any videos demonstrating motion or any explanation for how the system works other than vagaries about perpetual energy. So, does this thing exist—and did this company really build two of them? Does it work…or, well, somehow do something?
At $250,000, Virgin Galactic is probably out of most people’s price range; even reduced gravity flights run $5k. You may be in luck, though, as [Justin] and his friends have built a spinning room for $350 (Warning: loud noise @ beginning) that can turn your world upside down. The video provides a time-lapse of the build, but you’ll probably want to skip ahead 5 minutes in for the real fun.
It may not be anti-gravity, but holding onto furniture to keep from flying into the ceiling looks pretty entertaining. The room works like the fairground favorite “Gravitron” ride turned sideways. 2 forklifts support a massive wooden cube, which includes familiar features from home: drywall, flooring, and some furniture. [Justin] managed to borrow two car wheels, which he mounted in the middle of the walls on opposing sides of the cube. Two casters support each rim, and the forklifts hold the casters just high enough to allow a few friends to manually sling everything around.
Continue reading “Zero gravity (sort of) on a budget”
This robot artist, the Drawbot, produces images using an Arduino and Processing. A piece of paper is attached to a wall as a stylus connected to a couple of stepper motors scribbles out patterns that gradually become the image seen above. Each drawing is different and can take several weeks of constant operation to finish. That must have made debugging a real problem for [Harvey] during development. We wonder if this would work with homemade pencils?