Broadcast Engineer at BellMedia, Computer history buff, compulsive deprecated, disparate hardware hoarder, R/C, robots, arduino, RF, and everything in between.
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"Removing the water": physically-accurate color correction algorithm for underwater photography

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Researcher Derya Akkaynak developed a photogrammetry algorithm that corrects underwater photography to remove color haze created by backscattering -- in effect "removing the water" to show the underwater world in its fullness of color and detail. The results are beautiful and crystal clear.

Why do all the pictures you take underwater look blandly blue-green? The answer has to do with how light travels through water. Derya Akkaynak, an oceangoing engineer, has figured out a way to recover the colorful brilliance of the deep.

You can read the scientific paper at OpenAccess: Sea-thru: A Method For Removing Water From Underwater Images [PDF]

The Sea-thru method estimates backscatter using the dark pixels and their known range information. Then, it uses an estimate of the spatially varying illuminant to obtain the range-dependent attenuation coefficient. Using more than 1,100 images from two optically different water bodies, which we make available, we show that our method with the revised model outperforms those using the atmospheric model. Consistent removal of water will open up large underwater datasets to powerful computer vision and machine learning algorithms, creating exciting opportunities for the future of underwater exploration and conservation.

A funny problem with the video: at 2:56 in, they're seen using Photoshop's color balance tools to edit one of the images, while Akkaynak says "this method is not photoshopping an image." It's surely just a terrible edit and they were doing a comparison, but it made me wonder, so I fired up Photoshop to see how it does.

Here, the paper's example is seen raw (top left), corrected by Photoshop's Auto Color tool (top right), corrected by Sea-Thru (bottom left) and corrected by me using the color balance sliders in Photoshop (bottom right).

Sea-Thru obviously trounces Photoshop's automatic color correction.

On the manual effort I was able to lose the blue and create the appearance of a color-corrected image, but I was not able to recover the redness of the sea bed revealed by Sea-Thru. Moreover, the attempt looks to have given the coral an inappropriate reddish cast.

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tekvax
8 days ago
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Burlington, Ontario
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Dog has learned to "speak" with a soundboard: "Outside. Come now."

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Koko the gorilla (RIP) amazed the world when she learned to communicate with humans, but now there's a dog whose learned to "talk." Not with sign language, but with a soundboard. According to her speech-language pathologist person, Christina Hunger, Stella the dog has already learned 29 words and several phrases. By pressing her paw on the pre-programmed buttons, she has learned to say what's on her mind.

People:

One day, the [18-month-old] pup was whining at the front door and started pacing back and forth. Hunger assumed that she needed to go outside. Instead, Stella walked to her device and tapped out, “Want,” “Jake” “Come” then stood in front of the door until Hunger’s fiancé, Jake, came home a few minutes later and then Stella immediately pressed “Happy” and rolled over for a belly rub.

Here are a few videos of Stella doing her thing:

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Hello there everyone!! 🤗 Welcome to the Hunger for Words community! I’m THRILLED you’re here! I feel completely honored by this outpouring of enthusiasm and inspiration ✨✨ Here is a fun Stella series to kick off this new chapter! • Jake and I were discussing taking Stella to Petco. She was certainly listening...! • Video 1: Stella said “Goodbye outside.” This is the third time in the past few weeks that Stella has combined “good” and “bye” to say “Goodbye” instead of just “bye”! • Video 2: Jake said he wanted to hang our spice racks first, started the project, and Stella told him, “Later Jake” 😂😂 (Translation: Do that later, I want to go!) • Video 3: Stella came full circle with her message and told us she was REALLY ready to leave by saying, “Bye bye bye good bye!” (Looks like we have ourselves a little @nsync fan 😜) • I hope you all have a great day!

A post shared by Christina Hunger, MA, CCC-SLP (@hunger4words) on

How fantastic is that?!

If you want to follow Stella on Instagram (and I think you do!), head to Hunger for Words. Also, check out the Hunger for Words website. There's a "day in the life" post that is worth a look.

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tekvax
12 days ago
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Burlington, Ontario
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Console clock

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$ while sleep 1; do tput sc; tput cup 0 $(($(tput cols)-29)); date; tput rc; done &
You will see it on the corner of your running terminal.

commandlinefu.com

Diff your entire server config at ScriptRock.com

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tekvax
16 days ago
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Burlington, Ontario
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The Long History Of Fast Reactors And The Promise Of A Closed Fuel Cycle

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The discovery of nuclear fission in the 1930s brought with it first the threat of nuclear annihilation by nuclear weapons in the 1940s, followed by the promise of clean, plentiful power in the 1950s courtesy of nuclear power plants. These would replace other types of thermal plants with one that would produce no exhaust gases, no fly ash and require only occasional refueling using uranium and other fissile fuels that can be found practically everywhere.

The equipment with which nuclear fission was experimentally proven in 1938.

As nuclear reactors popped up ever faster during the 1950s and 1960s, the worry about running out of uranium fuel became ever more present, which led to increased R&D in so-called fast reactors, which in the fast-breeder reactor (FBR) configuration can use uranium fuel significantly more efficiently by using fast neutrons to change (‘breed’) 238U into 239Pu, which can then be mixed with uranium fuel to create (MOX) fuel for slow-neutron reactors, allowing not 1% but up to 60% of the energy in uranium to be used in a once-through cycle.

The boom in uranium supplies discovered during the 1970s mostly put a stop to these R&D efforts, with some nations like France still going through its Rapsodie, Phénix and SuperPhénix designs until recently finally canceling the Generation IV ASTRID demonstrator design after years of trying to get the project off the ground.

This is not the end of fast reactors, however. In this article we’ll look at how these marvels of engineering work and the various fast reactor types in use and under development by nations like Russia, China and India.

The ‘fast’ part of fast reactors

As alluded to in the introduction, the speed of the neutrons in their fission process is what makes a “fast” reactor fast. Whereas light-water reactors (LWR: including PWR, BWR and SCWR) employ regular water as a neutron moderator, fast reactors do not. The neutrons that are emitted by 235U and other isotopes when they are subjected to a nuclear chain reaction normally travel at a significant speed. Interestingly enough, the speed at which a neutron travels determines the likelihood of it interacting with a specific nucleus.

The production of transuranic actinides in thermal neutron fission reactors. (CC-BY-SA-3.0)

This neutron cross-section property is used to categorize nuclides. When a nucleus absorbs a neutron and either keeps it or decays, it is said to have a capture cross section. Nuclides that fission (shatter) have a fission cross section. Other nuclides will simply scatter the neutron and are said to have a scatter cross section. Nuclides with large absorption cross sections are called neutron poisons, as they will simply absorb neutrons without decaying, essentially starving the nuclear reaction of neutrons.

A nuclide like that of 238U is interesting in that has a non-zero rating in each of those three cross-section categories, which at least partially explains why it makes for such a poor fuel for a LWR. This is quite unlike 235U, which has a solid fission cross section, but only at neutron speeds which are significantly lower than those of freshly emitted neutrons during the nuclear chain reaction. This means that the neutrons in a LWR have to be slowed down (reduced to ‘thermal’ speeds) for a fission process to be sustained.

Here the water finds itself amidst the fuel rods, with neutrons flying everywhere as the fission process has been kick-started by the startup neutron source. These fast neutrons readily collide with the hydrogen atoms in a water molecule, which causes the former to lose kinetic energy and as a result slow down. This allows them to then careen straight into another (or the same) fuel rod and successfully fission another 235U nuclide.

This property of water as moderator also acts as a safety feature. If the temperature in the core increases, the water will end up boiling, which causes it to turn into a gas, meaning fewer water molecules per volume and thus less moderating of neutrons, effectively reducing the rate of the nuclear chain reaction. This negative void coefficient is a common feature of all commercial reactors in use today, with noticeable exceptions being the infamous RBMK design and the heavy water-based Canadian CANDU reactors.

Breeding plutonium for fun and profit

Ring of nearly pure plutonium. (Credit: Los Alamos National Laboratory)

As mentioned earlier, 238U is a bit of an odd one when it comes to its neutron cross-section. Its triple-dipping means that it both absorbs and scatters neutrons in addition to the occasional fission event, with the former being significantly more prevalent. Upon capturing a neutron by a 238U nuclide, it transforms (transmutates) into 239Pu (and some 239Pu into 240Pu). This process also happens in an LWR reactor, but is done on purpose in a fast breeder reactor (FBR) to create plutonium.

A fast reactor omits the neutron moderator completely, as it requires the fast neutrons in order to convert as much of the 238U to 239Pu. In the FBR, an enriched 235U core is covered with a mantel of mostly 238U, which then slowly transmutates into mostly 239Pu and 240Pu, for use in MOX fuel. This means that the FBR is a relatively simple design, using either a cooling loop or pool design. Coolants used are generally a liquid metal or sodium-based coolant, as these are weak neutron moderators, while still possessing excellent heat transfer properties.

France’s fast reactors have been used to both generate electricity just like any other thermal plant, while also providing the plutonium needed for creating MOX fuel that can be used in its LWRs. A major reason for this process was energy independence, as France does not have significant uranium resources, this would have allowed it to obtain up to sixty times more energy out of the uranium it imports, allowing every kilogram of uranium to last sixty times as long.

Experimental Breeder Reactor II (EBR II), prototype to the US Integral Fast Reactor.

Other recent efforts involving fast reactors include the Integral Fast Reactor in the USA and Japan’s Monju (succeeded by the FNR Jouyou sodium-cooled fast reactor). A nice side-effect of breeding uranium fuel is that it significantly reduces the volume of the spent fuel at the end of a once-through fuel cycle, as much of the original 238U will have been burned as 239Pu fuel in the LWR. The spent fuel from LWRs can then be passed through an FBR again, to burn up ‘waste’ isotopes which LWRs cannot use, as well as to create more fuel for LWRs.

Unfortunately, fast reactors have the disadvantages of being more expensive than LWRs and the challenges of sodium-based cooling (mainly avoiding contact with water) have meant that since the 1970s crash in uranium prices, it’s generally more economically viable to create new fuel out of uranium ore and store or dump the spent fuel after a once-through run in an LWR.

Despite an LWR doing some breeding of its own, converting some of the 238U to plutonium, an LWR’s spent fuel still contains about 96% of the original uranium along with 3% of ‘waste’ isotopes and about 1% of plutonium isotopes.

Burn, baby, burn

While most fast reactors are used to breed fuel for LWRs, another type aims to use all of the fuel locally. This type of fast reactor is called a Fast-Neutron Reactor (FNR) and is essentially a different core configuration of the FBR design, with no fundamental differences. Any fast reactor can in theory be used to breed fuel and burn it.

Schematic of a sodium-cooled fast reactor.

Changing an FBR design to FNR involves removing the 238U blanket and installing stainless steel (or equivalent) neutron reflectors. In the resulting reactor, the produced neutrons are kept inside the core, keeping them available for new interactions with nuclides and continuing the fission process.

As a result, an FNR can effectively fission and transmutate the nuclides in the fuel until no significant amounts of actinides (which includes uranium and plutonium) remain. This can be combined with pyroprocessing, which can reprocess today’s spent fuel from LWRs for burn-up in FNRs, effectively closing the nuclear fuel cycle.

French Resistance

Not only cold economics have played a role in stifling fast reactor development in the West. Fast reactors have caught the attention of terrorists and politicians alike. The former is illustrated by the 1982 rocket attack by Chaïm Nissim on the Superphénix FBR with five RPG-7 shoulder-fired rocket-propelled grenades, as he believed that an FBR “can explode with their fast neutrons”. This particular FBR was a joint project between France, Italy and Germany, with originally the goal to build FBRs based on the Superphénix design in both France and Germany.

The Superphénix reactor building. (© Yann Forget / Wikimedia Commons / CC-BY-SA)

From the beginning the Superphénix faced strong political resistance by anti-nuclear groups, with the closure of this prototype reactor in 1998, at a time when anti-nuclear Green ministers were in charge of the French government. The only reason given was that the project wasn’t viable due to its ‘excessive costs’, being 9.1 billion Euro since 1976, or about 430 million Euro a year. This despite the reactor’s issues with the sodium loop having been resolved in 1996 and the reactor having made money by producing electricity during most of its operational lifespan.

Current development

The situation in the US, France and other Western countries contrasts sharply with that in the Soviet Union, China and India. Starting in 1973, the BN-350 FNR on the shores of the Caspian Sea in what is now Kazakhstan provided 135 MW of electricity and desalinated water to the nearby city of Aktau. It only shut down in 1994 because the operator had run out of funds to purchase more fuel. In 1999 the reactor was fully retired, after 26 years of service.

The BN-series of FNRs continued with the BN-600, which was constructed at Beloyarsk Nuclear Power Station in Russia. This uses a sodium pool-based design and has been in operation since 1980, providing 600 MW of power to the local grid. Despite suffering a few dozen minor issues mostly related to leaks in the sodium tubing, its operational history has been largely trouble-free despite being the second prototype in the BN-series.

The BN-800 FNR at Beloyarsk.

The BN-800 reactor, built at the same Beloyarsk site, is the final prototype in the BN-series, providing 85% reduction in operating costs over the LWR VVER-1200 reactor, with the BN-1200 intended to be the first mass-produced fast reactor. Construction of the first BN-1200 reactors is currently pending. China’s experimental CEFR FNR and CFR-600 pilot FNR are based on Russian BN-reactor technology. Russia is also working on a lead-cooled fast reactor, called BREST.

India has found itself with abundant thorium (232Th) resources, which has led to it focusing on an ambitious thorium-based development program alongside uranium reactors. The thorium program consists out of three parts. First, they produce plutonium from uranium using LWRs. Then a FNR creates 233U from 232Th while burning the plutonium. Finally, advanced heavy water reactors would use the resulting thorium as fuel, and the 233U and plutonium as driver fuels.

Other Generation IV FNR designs are also under development, such as the helium gas-cooled fast reactor (GFR).

Closing the fuel cycle

As mentioned earlier, FNRs are capable of using all of today’s spent fuel (often referred to as ‘nuclear waste’) as fuel. Combined with pyropocessing, this would allow for nuclear fission reactors to operate with practically zero waste, using up all uranium fuel, minor actinides and so on. This has been a major goal of Russia’s nuclear program, and is one of China’s, Japan’s and South Korea’s nuclear programs as well.

Along with efforts in the US (mostly Argonne National Laboratory and its IFR pyroprocessing), South Korea’s KAERI is actively working on closing South Korea’s fuel cycle. The goal is to separate the spent fuel from everything that is still viable as fuel, meaning everything that is still radioactive. Unfortunately cooperation between Russia and nations other than China, as well as between South Korea and Japan or China has been very limited on this type of research on mostly political grounds.

Despite this, it seems that efforts are well underway to make Generation IV FNRs the reactor of choice for new plants, not only allowing for spent fuel to be used up fully and closing the fuel cycle, but also increasing the energy we can obtain from uranium (and conceivably thorium) by many times, increasing even the pessimistic estimate of about 100 years of uranium fuel to a comfortable few-thousand years, while not leaving the world a legacy of spent uranium fuel.

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tekvax
16 days ago
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Burlington, Ontario
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Captivating Clock Tells Time With Tall Tubes

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Time is probably our most important social construct. Our perception of passing time changes with everything we do, and when it comes down to it, time is all we really have. You can choose to use it wisely, or sit back and watch it go by. If you want to do both, build a clock like this one, and spectate in sleek, sophisticated style.

[ChristineNZ]’s mid-century-meets-steampunk clock uses eight ILC1-1/8Ls, which are quite possibly the largest VFD tubes ever produced (and still available as new-old stock). In addition to the time, it displays the date, relative humidity, and temperature in both Celsius and Fahrenheit. A delightful chime sounds every fifteen minutes to remind you that time’s a-wastin’.

The seconds slip by in HH/MM/SS format, each division separated by a tube dedicated to dancing the time away. The mesmerizing display is driven by an Arduino Mega and a MAX6921 VFD driver, and built into a mahogany frame. There isn’t a single PCB in sight except for the Mega — all the VFDs are mounted on wood and everything is wired point-to-point. Sweep past the break to see the progressive slideshow build video that ends with a demo of all the functions.

Those glowing blue-green displays aren’t limited to clocking time. They can replace LCDs, or be scrolling marquees.

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tekvax
16 days ago
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Burlington, Ontario
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Turning Old Toggle Switches Into Retro-Tech Showpieces

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While those of us in the hacking community usually focus on making new things, there’s plenty to be said for restoring old stuff. Finding a piece of hardware and making it look and work like new can be immensely satisfying, and dozens of YouTube channels and blogs exist merely to feed the need for more restoration content.

The aptly named [Switch and Lever] has been riding the retro wave for a while, and his video on restoring and repairing vintage toggle switches shows that he has picked up a trick or two worth sharing. The switches are all flea market finds, chunky beasts that have all seen better days. But old parts were built to last, and they proved sturdy enough to withstand the first step in any restoration: disassembly. Most of the switches were easily pried open, but a couple needed rivets drilled out first. The ensuing cleaning and polishing steps were pretty basic, although we liked the tips about the micromesh abrasives and the polishing compound. Another great tip was using phenolic resin PCBs as repair material for broken Bakelite bodies; they’re chemically similar, and while they may not match the original exactly, they make for a great repair when teamed up with CA glue and baking soda as a filler.

3D-printed repairs would work too, but there’s something satisfying about keeping things historically consistent. Celebrating engineering history is really what restorations like these are all about, after all. And even if you’re building something new, you can make it look retro cool with these acid-etched brass plaques that [Switch and Lever] also makes.

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tekvax
16 days ago
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Burlington, Ontario
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