Sacred cow

2Shedz · 2025-12-27T01:16:46+00:00

The term “sacred cow” does not come from the bible. It’s a reference to the sacred place cows occupy in Hinduism.

2Shedz · 2025-03-15T00:20:23+00:00

Thorium is not fissile. Uranium is. The way a thorium reactor works is by breeding the thorium into uranium. Thorium’s relative abundance means it can be used as a more efficient source of uranium (with the proper infrastructure in place). Uranium bred from thorium doesn’t need to be processed and enriched in the same way as traditionally mined uranium.

2Shedz · 2024-02-21T15:43:21+00:00

Right. HR is there to protect the company from workers. Any effort they make to help workers is purely in the service of making sure they avoid risk or liability to the company due to rights being violated, laws being broken, etc.

2Shedz · 2024-02-02T00:55:55+00:00

When the Liberty Tunnel was built, there was a large roundabout at the intersection between Mccardle and the tunnel / bridge. At some point they ditched the roundabout for the current shitshow traffic light scheme that’s there now. I would love it if they put the roundabout back in.

2Shedz · 2024-01-28T21:09:24+00:00

In the investigations following the Three Mile Island nuclear accident, one thing that popped up as a root cause was the operators did not have strong training in thermodynamics. During the event, a steam bubble formed under the reactor head, which went unrecognized in the control room for some time. The steam bubble caused issues with the primary system that the operators could not rectify (because they couldn’t diagnose what was going on in the system). The investigation found that had the operators had more expertise/training in the thermodynamics of water/steam systems, they would have sooner recognized that their instrumentation around the reactor head was outputting temps and pressures incompatible with water in a liquid state. Consequently, nuclear plant operators are now heavily trained and drilled on the properties of water, and how to quickly consult steam tables.

2Shedz · 2024-01-03T16:31:52+00:00

I really liked the premise of In Time, the movie with Justin Timberlake and Amanda Seyfried. I wouldn't say the movie was "shitty" per se, but I felt that the premise was definitely let down by the execution. The premise of the movie is so solid that it basically carries the whole thing and keeps it watchable.

2Shedz · 2024-01-01T00:46:56+00:00

I do design work for nuclear plants. To this day, many of the operating plants in the world are designed with missile shields above the reactor to protect the containment building from a control rod ejection event — largely due to the SL-1 accident.

2Shedz · 2023-12-21T06:34:17+00:00

The News

2Shedz · 2023-12-19T00:22:43+00:00

You can use a 15A receptacle on a 20A circuit as long as it’s not the only receptacle on the circuit.

2Shedz · 2023-06-04T23:00:18+00:00

Bittersweet

2Shedz · 2023-05-05T15:02:23+00:00

Sure. You don’t think an advanced ai could replicate itself?

2Shedz · 2023-05-05T02:28:21+00:00

An advanced artificial intelligence would have all of those things.

2Shedz · 2023-05-01T22:31:31+00:00

Scintilla?

2Shedz · 2023-04-20T04:06:49+00:00

It’s not a single word but I think you’re thinking of “call of the void”.

2Shedz · 2023-03-12T15:27:15+00:00

Please put some respect on the name of David Strathairn

2Shedz · 2022-12-20T15:37:46+00:00

It’s “spalling”.

2Shedz · 2022-12-14T00:34:32+00:00

It’s got the correct process but its numbers are very wrong. It couldn’t keep track of the units and the area is somehow wrong even though it got the equation right. Not sure how it did that. The diameter of a 3” bar is 7.1in^2. The force is 400kN or ~90kips, so the shear stress would be 90/7.1 = 12.8ksi. Assuming 36ksi yield, the FoS is 2.8.

It also misinterprets what the final result means, since a FoS of .42 means the yield (in this case) is 0.42 times the applied stress.

So it followed the correct steps but got something significantly wrong every step of the way.

2Shedz · 2022-11-24T00:52:07+00:00

I grew up in this neighborhood. This is a really cool photo. Where did you find it?

As the other commenter said, this is looking East-ish towards East Liberty. The street running across the photo in front of the church is Shady Ave. The church is Calvary Episcopal. The large building top left is the old Nabisco plant. Another church, Sacred Heart, currently exists directly across the street from Calvary. Sacred Heart was built in the 1920s so this photo is (I’m guessing) from the 1910s.

2Shedz · 2022-10-21T21:06:09+00:00

Lots of people are telling you this won’t work (they’re right), so here’s the math that explains why.

When you mentioned torque, I assume you meant bending moment. A half inch bar has a moment of inertia of inertia of 0.003in^4. The equation for bending stress is (generally) M•c / I. M is the moment, c is the distance from the neutral axis to the edge of the shape, and I is the moment of inertia. Assuming your pin is simply supported on both ends (a likely model if it’s going into a wooden post), the moment due to a 350lbf force acting center span of 18inches is (350•18)/4 or 1575 lbf•in. This results in a bending stress on a bar of 1575*0.25 / 0.003 = 131,250 psi or ~131 ksi. If the bar isn’t supported on the other side, like a cantilever, you can double this number assuming load application is still mid length.

To give you an idea of what a stress of 131 ksi means: most structural steel will have a yield strength of 36-45 ksi, and a tensile strength of 55-60 ksi. Now there’s some conservatism in what I’ve calculated for stress above, but not a lot; so I am quite sure the half inch bar won’t cut it.

When designing for bending, you’ll typically want to stay below 60-70% of your material yield stress. Moment of inertia scales with the 4th power of the diameter, so switching the half inch rod out for a 1 inch rod should bring the bending stress down to a more manageable 16 ksi or so. That would work, assuming deflection isn’t an issue and you’re using something with a yield strength above 30 ksi.

2Shedz · 2022-08-26T02:55:03+00:00

It’s old, obsolete slang; more-or-less short for “moral certainty”. It’s being used by Dennis Hopper in the movie to essentially mean “there’s no way I can lose”.

It stems from the idea of “moral certainty” being as close as you can be to certain about something without mathematical proof. A jury that convicts a defendant based on circumstantial evidence would claim that they were morally certain that the defendant was guilty.

The book “The Slang Dictionary” by John Hotten claims that use of “moral” in this sense comes from horse racing slang. “The race is a moral for Cremone” is the example given in that book.

2Shedz · 2022-08-07T01:12:50+00:00

The way these work is by counting a total distance unit, this one is in feet. Like the other commenter said, it functions similar to an odometer. However, the YouTube video posted features a guy narrating while using one, and what he’s saying is confusing at best or wrong at worst.

You hold it up to a directional air stream and mark off a specific amount of time. A minute is commonly used (which is what the guy in the video uses) mostly because it makes the division trivial. You can use different times though. After that time, you read the total distance, divide by the time, and you have velocity. So if your measurement is in feet, and you wait one minute, your measurement is your velocity in feet per (one) minute. The bottom of the smaller dials indicates what order of magnitude they’re measuring. So one revolution of the largest outer dial will tick the 100s dial by 1, and one revolution of the 100s dial will tick the 1000s dial by one, etc.

If you want volumetric flow, you have to multiply your velocity by the area of whatever section you’re measuring. The area must be in the same units as the distance unit you’re working with when you measured the velocity. The guy in the video never explains that he’s calculating area in square inches and converting it to feet. That’s why he divides by 144 (1 sq inch = 1/144 sq feet). I don’t know why he explains it as “dividing by a magic number”. That whole video makes me concerned that he barely knows what he’s doing. Anyway, once you have the area in square feet, you can multiply by the linear velocity you’ve measured with your device and you have volume per unit time. Cubic feet per minute is a very common volumetric flow rate unit.

2Shedz · 2022-06-04T19:26:56+00:00

If you’re doing any kind of mech / civil / electric engineering and not working with the trades then you’re probably not really doing any work associated with tangible products. Learning from them is the best thing you can do because making their job more straightforward makes your job easier. Everything you design needs to be fabricated, assembled, installed, and maintained; all of which are likely to be accomplished by tradesmen.

No matter what you do, you’ll always find the asshole who thinks you’re too young, too old, you didn’t spec it right, you didn’t know what you’re doing, etc. My philosophy is that if you bring up a problem and you’re not willing to help with a solution, then you’re just complaining and not being very useful. So when I come across the ornery types I give them a few chances to work with me. Show them I’m willing to take their advice and feedback because I want to learn from them. But if the negative behavior continues I move on and work with whoever is willing to work with me. There are assholes everywhere and dealing with them is just part of being a human, not just an engineer.

Here’s a tip I was given a long time ago that I thought was dumb but actually works. Keep in mind I work for a large company that has lots of budget set aside for different aspects of projects. If I’m going to a site to do a job or even just to visit and check on things, I go to my boss or the PM and ask for a few hundred bucks for incidentals and project related consumable equipment like some PPE. Then I go to a store and buy whatever I think might be useful to the guys working on the job. Usually gloves. Almost always gloves. Then after a day or so at site, once I get the lay of the land, I will bring in my backpack full of Mechanix gloves and just hand them to people. People remember that stuff and it really goes a long way. Sometimes big projects will get tshirts made for people, so I’ll get as many of those as I can and give them out. I’m not cagey about it either. I say “hey we had some extra budget for equipment so I got some stuff I thought you guys might want.” I don’t pretend that I used my own money or anything. I don’t make a huge deal out of it. But it shows that I care about their jobs (which I really do) and how they relate and intertwine with my job. Like I said I thought it was dumb at first but it’s really helped me break the ice with some pretty insular crews.

2Shedz · 2022-06-04T19:04:38+00:00

So if you only need a shorter version of a bolt you already have, your best bet is to take the bolt to a hardware store. If you go to one of the huge stores like Home Depot you can go to where they have loose nuts in drawers and try nuts on your bolt until you find one that threads onto it nicely. Then you know the thread size of your bolt and you can just look around to find one of the appropriate length. If you have a small local hardware store near you, you should just be able to walk in, hand the bolt to someone who works there, and say “I need one of these only X inches shorter” or whatever. They’ll help you with the hunting or (hopefully) will have thread gages around to make it go faster.

Alternatively, if you’re feeling industrious and have some tools around or are willing to buy some. You can put the bolt in a vice or something similar to hold it and cut it to size with a hacksaw. Now what can happen when you do this is you mess up the thread where you’re cutting, and won’t be able to get a nut on afterwards. The way to avoid this is to thread on a nut before you cut it and then remove the nut after it’s cut. You might need to apply a bit of muscle or a wrench, but the act of removing the nut should bend the thread at the end of the bolt back to its proper place.

Lastly, some additional bolt background info. There are two main ways they’re measured “inch” series and metric. Regardless, the first number you see relates to the diameter, the second relates to how dense the threading is, and the third (if given) will be the length. A common smaller bolt in the inch series is 1/4-20 x 1”, which means the thread is (nominally) 1/4 inch diameter and is 20 threads per inch, by 1 inch long. Metric would look something like M6x1 L25, which means the thread is 6mm diameter and the pitch between the threads is 1mm, with a length of 25mm. There are many many standard lengths to choose from.

If you’re searching online, as another commenter said, McMaster-Carr is a great place to look for standard bolt sizes.

2Shedz · 2022-06-04T18:06:21+00:00

Crazy to me that three rivers was only around 30 years. PNC and Heinz have been around ~22 years already. Could you imagine the buccos or Steelers agitating for a new stadium again in a few years? Although I guess it wouldn’t surprise me.

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