Engineering

A friend recently pointed out that, despite most microwave ovens having a Popcorn function, most bags of popcorn specifically say NOT to use that function. It got me wondering how the Popcorn button works (or doesn't work). Apparently there are several different approaches in common use.

Basic method: Microwave on full power for a set amount of time. With clumsy designs like this I'm not surprised the popcorn sellers would discourage using the Popcorn button.

Improved method 1: Have the user enter the weight of the popcorn bag. The microwave adjusts the cooking time accordingly. Better, but still not great.

Improved method 2: Add a humidity sensor to detect the humidity change when the bag bursts open. Much better; now we have a real-time feedback mechanism.

Improved method 3: Add a microphone to listen for the time between pops, just like humans do. I had no idea this was a real thing, but apparently it has existed for years. For example, Whirlpool calls its implementation "AccuPop."

Does anyone have another clever idea to add to the list?

This video has some fantastic demonstrations of how sewing machines work. If you're mechanically inclined then it's definitely worth a watch. The mechanisms that grab, twist, and pull the thread are wonderfully clever and elegant.

The dark autumn evenings reminded me of a particular street light in my neighborhood that's an awful purple color. I finally dug into what causes that. The "white" LEDs are really blue LEDs with a phosphor-based coating on the lens. The coating is excited by the blue light and emits other wavelengths, approximating white light. If the phosphor coating degrades or delaminates then more blue light escapes, making the overall light look more blue-violet.

The post image is from an entry on the Dark Sky Consulting blog.

This recent research paper has some pictures of the actual failure on LEDs.

I'm looking for a book (preferably eBook) which explains one or more engineering projects in great detail.

Anyone have any recommendations?

The original design of the Sydney opera house featured roof sections with unique curves. This caused two major problems: (1) the structural analysis was very difficult, and (2) it made construction more expensive since they could not reuse construction details among the roof sections. Eventually the engineers realized they could approximate the roof sections as segments from a single sphere. This greatly improved both problems.

This post inspired by a recent episode of the Cautionary Tales podcast. I never knew what a messy project the opera house had been.

You really have to watch the video in the linked URL to appreciate this little guy.

Archive link for those who prefer it.

Posting a second picture that shows and earlier stage in the process. Multiple charges ignite to remove the canopy from a CF-18 Hornet immediately before the pilot ejects. Photo from ejectionsite.com, which has more info on the incident.

A post on NCD sent me down a rabbit hole reading about ejection seats. Do we have anyone here who can share some first-hand knowledge about the designs? I didn't fully appreciate these products before: thousands of parts, multiple precisely timed pyrotechnic charges, and big consequences for failure. That sounds like a very stressful development project.

The picture above is a British pilot ejecting from his Harrier in Afghanistan in 2009. He was lucky and was able to resume flying.

cross-posted from: https://lemmy.sdf.org/post/604604

A sort of museum style tour of some jet engine compressors at a repair shop.

The valve core contains a specially designed wax. The wax expands as it is heated, forcing the valve open and allowing engine coolant to flow to the radiator. When the wax cools and contracts the valve is closed by a return spring.

More modern cars have a "map controlled" thermostat. These incorporate a heating element to melt the wax prematurely if the engine computer demands more cooling.

Here is the full video with narration.

And credit to Jalopnik for the animated gif.

I wonder how many people understand the planning and work that goes into making hiking trails and shelters for us weekend warriors. For example, here's a sample trail project package following the US Forest Service's standard plans and specifications. A trail is so much more than a strip of bare ground.

The image is a classic plan for an Adirondack shelter. They are common in the forests of New York and along the Appalachian Trail.

cross-posted from: https://lemmy.world/post/3895697

cross-posted from: https://kbin.social/m/[email protected]/t/384191

Tesla is facing issues with the bare metal construction of the Cybertruck, which Elon Musk warned was as tricky to do as making Lego bricks

I had an idea a little while ago that tunnel boring machines should just keep going. Think of all the tunnel we could have if all the TBMs just never stopped. We could have an ever growing tunnel network that could be tapped into as needed.

cross-posted from: https://lemmy.ml/post/3737290

Uranium fever has done and got me down Uranium fever, it's spreadin' all around

Impending nuclear renaissance?

This 99% Invisible podcast touches on the history of mechanical lubrication, from vegetable oils to whale blubber to modern synthetics. Featuring Bill Nye the Science Guy, who is apparently a direct descendant of William Foster Nye, the founder the Nye Lubricants.

I know there isn't a lot of information available yet, but I'm not above playing Monday morning quarterback. What do you think about this incident?

Russianspaceweb.com has some interesting info on the probe.

CBC has a decent article that doesn't seem to be paywalled.

In 2021, two University of Washington engineering students completed a pipe-inspecting rover named hydroCUB as a capstone project. The project was proposed by the Washington State Department of Transportation. Full story here.

A year later the WSDOT was experimenting with a further iteration of the same concept, nicknamed Elvis. Here's Elvis:

Another good video from Steve Mould.

Log bridge (crib trestle) on the Columbia and Nehalem Valley Railroad, Columbia County, Oregon.

Source

An F-16 model in a flow visualization test using smoke and a laser light sheet to illuminate the smoke.

Source

Image courtesy of the Michigan Department of Environment, Great Lakes, and Energy.

Source: https://www.michigan.gov/egle/-/media/Project/Websites/egle/Documents/Programs/MMD/Landfills/Anatomy-of-a-Landfill-with-Glossary.pdf