For Questions That Don't Merit Their Own Thread

[FleshJeb]

18 hours ago, JoeSchmuckatelli said:

You should see the one on New Madrid.  Fascinating... And missing part 2 (angry face emoji).  Hoping they will publish 2 soon - its really good! 

I watched that one as well as the fishy one.  Both excellent.

Speaking of the fishy one, this channel covers a lot of marine (no crayons) biology. It's much more "atmospheric" and relaxing channel, but quite informative:

 

Which leads me to the thought: We're pulling out all this biomass from the ocean, and effectively "onshoring" it. If we're not then sequestering that carbon for its atmospheric lifetime of 300-1000 years, then it's a very CO2-positive process.

There's potentially an argument to be made for pumping untreated wastewater off the edge of the continental shelf, with the side effect of it contributing to phytoplankton blooms and supplementing marine snow. In arid areas it's probably better to treat it and irrigate crops, but in wetter zones?

[JoeSchmuckatelli]

24 minutes ago, FleshJeb said:

marine (no crayons)

That got a laugh - thanks!

 

[FleshJeb]

1 hour ago, JoeSchmuckatelli said:

Totally random question:

If I buy a cheap photo printer - will that print graphic arts projects better than my color inkjet?

(My daughter is a pretty talented artist - and the inkjet doesn't capture some of the detail she can do with her Wacom).

I called my ex-wife (who is a mediocre graphic designer), and she said you'll really have to look at the specs to know., and that it's worth asking around on forums dedicated to graphic design. We both agree that the best option is probably to send the files out to a local print shop and have them do it on their really expensive printers. My office has outsourced all our high-end stuff to the blueprint shop around the corner and they do an excellent, cost-effective job.

Having seen my ex through her education, I know there are some complexities around optimizing color for print that your daughter might want to know if she chooses to pursue this as a career.

4 minutes ago, JoeSchmuckatelli said:

That got a laugh - thanks!

I know my audience.

Edited December 6, 2021 by FleshJeb

[JoeSchmuckatelli]

37 minutes ago, FleshJeb said:

If we're not then sequestering that carbon for its atmospheric lifetime of 300-1000 years, then it's a very CO2-positive process.

Yeah - that's a big part of the message.  The 'fish are hard to catch' thing they mention will be solved... and then that layer likely depleted.

 

16 minutes ago, FleshJeb said:

We both agree that the best option is probably to send the files out to a local print shop and have them do it on their really expensive printers.

Hmmm.  I was looking for a solution she could do in-house, where she could print stuff for herself and her friends.  Going the route you suggest is likely good for later, when she's hitting really top end stuff.  I'm just trying to give a talented middle-school kid a way to take stuff off the computer and into the 'real' world.

[FleshJeb]

1 hour ago, JoeSchmuckatelli said:

Yeah - that's a big part of the message.  The 'fish are hard to catch' thing they mention will be solved... and then that layer likely depleted.

Ugh, I didn't even think of that (obvious) angle.

1 hour ago, JoeSchmuckatelli said:

Hmmm.  I was looking for a solution she could do in-house, where she could print stuff for herself and her friends.  Going the route you suggest is likely good for later, when she's hitting really top end stuff.  I'm just trying to give a talented middle-school kid a way to take stuff off the computer and into the 'real' world.

Ah OK, then you're definitely going to have to do some product research. Consumer-grade printers should be the example they use in the dictionary under "caveat emptor".

If her software allows it, she may want to switch the color space to CMYK instead of RGB. Then it will look more like it will print.

[Shpaget]

Have you tried changing the paper you're printing on? There are dedicated types that might be more suitable.

[magnemoe]

On 12/5/2021 at 12:01 AM, StrandedonEarth said:

Okay, I got one. Why does a game like Civ 6, which is turn-based and is doing nothing if not receiving input (animations off) run so stupid hot? I swear KSP runs cooler, at least at low part counts. It's always done this, and I can't figure out what all the hubbub is about, why it would need to be generating that much heat doing nothing. And then when I do something it's running slow.

I suppose I should take it to that forum, but I don't hang there...

Only think I can think of is that the game AI is running in the background trying to figure out how to response. 
I assume you play like me, first moving units then deal with the cities, later does not affect the AI response much so it makes sense. 
Use task manager on advanced to check how much of the cpu its using. 

Also interesting if it use less at the start of an new game with few units and cities and if it uses less after some time?

[steve9728]

15 hours ago, JoeSchmuckatelli said:

Totally random question:

If I buy a cheap photo printer - will that print graphic arts projects better than my color inkjet?

(My daughter is a pretty talented artist - and the inkjet doesn't capture some of the detail she can do with her Wacom).

Bought a second hand HP printer from a guy and well...believe it or not I only paid £2 and it was just over £30 for color and black cartridges.  It’s really useful but inkjet is definitely worse than the photo printer if you need really specific details: because my dad do plays photography and he used to draw anime as a career. But if just for human figures and scale drawings of people, inkjet are able to fully meet all the challenges

[Exploro]

In a recent project, my mechanics of materials class was given a simply supported beam with double overhanging free ends. The beam is symmetrically loaded with two identical concentrated loaded at the ends of the beam and a rectangular distributed load acting between the supports. Choosing to avoid the headache of superposition, I wrote a loading equation using singularity functions, iteratively integrating until I had the slope and deflection equations and then solved for the constants of integration. Nothing seemed to indicate anything would go wrong, and yet, when trying to show that the free ends would have the same deflection, I can't seem to get deflections that are identical. I know it is not due to the constants of integration. I repeated the calculations exhaustively, even plugging the system of equations into Wolfram Alpha's reduced echelon form calculator confirms the constants are what they should be. I'm at a loss as to what else could be wrong. Are symmetrically loaded beam with double overhangs a case where equations written with singularity functions break?

 

Edited December 6, 2021 by Exploro

[K^2]

8 hours ago, Exploro said:

Are symmetrically loaded beam with double overhangs a case where equations written with singularity functions break?

Shouldn't. Some integration methods could have trouble, but I would imagine Wolfram to handle it correctly. Is your load something like c₁H(L/2 - x)H(L/2 + x) - c₂δ(x-x_s) - c₂δ(x+x_s)? (I'm assuming load isn't structural and sags, distributing weight evenly, and supports are applied at a point.) I can't think of any reason why this would result in solutions that aren't symmetric. One thing you could try, and what I'd do to simplify the problem, is to enforce symmetry by solving for positive x only with additional boundary condition that deflection and slope at x=0 are zero. That way your loading is just a Heaviside + delta, which should be a lot easier to integrate, and then maybe do all the math in Fourier space to go back to continuous functions if I was doing this by hand. Of course, that doesn't help explaining what went wrong in your computation. Do you want to share a bit more details about the steps you've taken?

[monophonic]

On 12/5/2021 at 1:01 AM, StrandedonEarth said:

Okay, I got one. Why does a game like Civ 6, which is turn-based and is doing nothing if not receiving input (animations off) run so stupid hot? I swear KSP runs cooler, at least at low part counts. It's always done this, and I can't figure out what all the hubbub is about, why it would need to be generating that much heat doing nothing. And then when I do something it's running slow.

I suppose I should take it to that forum, but I don't hang there...

Usually it is mainly the graphics. Even when I am doing nothing but staring blankly at the screen trying to figure a way out of the mess my civ is in the game is still drawing the display 60 (or whatever fps you are getting) times a second. There are still many animations to draw, like the units' idle fidgeting, animated terrain details, what have you (I haven't actually played any Civ after 3 but these principles have remained the same since the first). On top of that the game engines in use are typically heavily optimized towards fast paced first person shooters (i.e. big money makers) where getting every last drop of performance is king and everything else, including power(=heat production) use optimizations, is subservient to that singular goal. Civ-style turn based grid map games just aren't worth optimizing for as performance is usually sufficient with the brute force approach even on older family use hardware.

20 hours ago, magnemoe said:

Use task manager on advanced to check how much of the cpu its using. 

As GPU calculation methods are getting more and more common, low CPU usage is no longer necessarily indicative of low calculation activity e.g. AI functions or such. High CPU use of course still indicates something is going on.

[ARS]

1 hour ago, monophonic said:

As GPU calculation methods are getting more and more common, low CPU usage is no longer necessarily indicative of low calculation activity e.g. AI functions or such. High CPU use of course still indicates something is going on.

That makes me wonder, how far you can 'compensate' the hardware below system requirement with other hardware (for instance, the RAM needed is 8, but you only have 4, though the processor is I7 instead of I5 system requirement. Or the GPU is below system requirement, but the RAM and processor is way above the system requirement)

[magnemoe]

32 minutes ago, ARS said:

That makes me wonder, how far you can 'compensate' the hardware below system requirement with other hardware (for instance, the RAM needed is 8, but you only have 4, though the processor is I7 instead of I5 system requirement. Or the GPU is below system requirement, but the RAM and processor is way above the system requirement)

To an limited degree, you can compensate for an slow disk drive with more ram as the game will cache more, an fast SSD work the other way but an game tend to have an minimum memory limit where performance fall to rock bottom or the game crashes.  Don't think an strong CPU help much if the GPU is weak or opposite. 

 

[Hyperspace Industries]

How big a solar panel do you need to power one of these?

I think it is mains powered.

I'm asking because I've been reading into atomic hydrogen, I found an old NASA paper which said that with a 15% storage efficiency (by mass, I think) it could have around 1200 seconds of isp. All the methods I found of storage involve magnetic coil containment. I've been thinking of storing it as hydrogen gas and using the arc mechanism in the above video to break it up and let it recombine in the nozzle.

YES, I KNOW IT'S NOT ENERGY POSITIVE, (I'm considering this as a way to get high thrust and good isp from electricity, almost all other methods have almost no thrust at all) but that is why I'm asking about the solar panels, a decently sized panel should be able to power mains electricity, also, we have 85% of the overall tank mass to play with, which could easily be made up of batteries (or capacitors) which are charged by solar power, and release that energy when an engine firing is needed.

My main question is: could this possibly work, or am I just overlooking something obvious again. In the very, very likely case that I am wrong, why am I wrong?

Edited December 7, 2021 by Hyperspace Industries
Link to the nasa paper download: https://www.researchgate.net/publication/23703764_Atomic_hydrogen_propellants_-_Historical_perspectives_and_future_possibilities

[JoeSchmuckatelli]

Okay - serious question time... Why aren't we launching from the Peruvian Andes?

I get that ocean adjacent launch sites are easy-access, and that mountains are hard - but there are railroads.

 

So I just watched the ULA launch; they got to Mach 1 45 seconds into flight.  That's pretty much 1,000 feet per second, so a mile every 4 seconds.  Clearly just attaining 15,000 feet is nothing for a rocket - but how much fuel is spent leaving the lower atmosphere?  With a high launch cadence, is there a break-even point where launching from 15,000 feet would make a difference and be cost effective over the ease and safety of an ocean-adjacent launch site?

[Hyperspace Industries]

18 minutes ago, JoeSchmuckatelli said:

Okay - serious question time... Why aren't we launching from the Peruvian Andes?

I get that ocean adjacent launch sites are easy-access, and that mountains are hard - but there are railroads.

 

So I just watched the ULA launch; they got to Mach 1 45 seconds into flight.  That's pretty much 1,000 feet per second, so a mile every 4 seconds.  Clearly just attaining 15,000 feet is nothing for a rocket - but how much fuel is spent leaving the lower atmosphere?  With a high launch cadence, is there a break-even point where launching from 15,000 feet would make a difference and be cost effective over the ease and safety of an ocean-adjacent launch site?

Also, shouldn't my question have been answered before you posted yours? Those are the rules, aren't they?

I don't care if my hypothesis in my question is wrong (even if it's obviously wrong), I just want to know if it's wrong and why.

[kerbiloid]

Still unclear.  He brought as an example a ~2 km high launch site.

But this is almost sea level, while the highest mountains are closer to the tropopause and to Max-Q.

[K^2]

11 hours ago, ARS said:

That makes me wonder, how far you can 'compensate' the hardware below system requirement with other hardware (for instance, the RAM needed is 8, but you only have 4, though the processor is I7 instead of I5 system requirement. Or the GPU is below system requirement, but the RAM and processor is way above the system requirement)

If the game isn't coded to do the algorithmic tradeoffs, which they usually aren't, very little. Once you hit a bottleneck, that's what determines performance. RAM is actually the worst, as the fallback for running out is starting to write to disk, and that is very slow.

9 hours ago, Hyperspace Industries said:

My main question is: could this possibly work, or am I just overlooking something obvious again. In the very, very likely case that I am wrong, why am I wrong?

The I_SP gain only really makes sense at a given temperature or a given power limit on your accelerator in an ion thruster. If you have excess energy to put into splitting H2 molecules, just double the cavity potential and get the same I_SP with molecular hydrogen instead.

Edited December 7, 2021 by K^2

[JoeSchmuckatelli]

2 hours ago, Hyperspace Industries said:

shouldn't my question have been answered before you posted yours? Those are the rules, aren't they

Mea culpa. 

Inadvertent rather than intentionally done! 

Btw - I really enjoyed the vid you posted.  Those old ones are quaint, but very straightforward. 

 

Thanks also for the Manley vid! 

 

[Hyperspace Industries]

1 hour ago, K^2 said:

cavity potential

What is that, also would atomic hydrogen increase thrust, or is that a dead end too?  I've figured out that tesla car batteries could probably provide the power needed for this sort of arc based atomic hydrogen rocket. (Before I found out your answer.)

Edited December 7, 2021 by Hyperspace Industries

[K^2]

2 hours ago, Hyperspace Industries said:

What is that

A lot of linear accelerators are built as banks of cavities with applied RF field providing electrostatic potential to drive charged particles through it. Not all thrusters are going to use the same principle, but there is going to be some sort of equivalent where more power gives you more thrust.

2 hours ago, Hyperspace Industries said:

I've figured out that tesla car batteries could probably provide the power

No. You don't want batteries in your ion drive engine. They are too heavy for the amount of energy they can hold. You are better off just burning kerosene at this point and using exhaust directly. The whole point of an ion drive is that you have something with enormous energy density that you can use to generate high I_SP by accelerating propellant directly. For example, you might use solar panels which can't give you a lot of power, but they can give you an huge amount of energy over the life time of the panel. Currently, the only attainable power sources that give you both the high power and high energy density are nuclear.

So if you're designing an ion drive engine, you're always going to be either building for a low thrust application with solar panels or nuclear RTG, or a high power system that's powered by a full nuclear reactor. No other existing power sources are remotely adequate.

[magnemoe]

5 hours ago, kerbiloid said:

Still unclear.  He brought as an example a ~2 km high launch site.

But this is almost sea level, while the highest mountains are closer to the tropopause and to Max-Q.

There is logistical problems building an launch complex in in say the Andes, Nepal or at Kilimanjaro who is hard to reach places. Have fun bringing an falcon 9 up to them, selected as its designed to be road portable.  You would need some serious road building to do this. And you need to overfly populated areas who might be in other countries who will be larger than you. 
Now you have Hawaii with tall mountains is inside the US and has some infrastructure as in roads to the observatories, who would not want an launch pad next to their telescopes:) 

[kerbiloid]

3 hours ago, magnemoe said:

Now you have Hawaii with tall mountains is inside the US and has some infrastructure as in roads to the observatories, who would not want an launch pad next to their telescopes:) 

Central Asia has many high mountains, too, in the relatively low-populated places. (If speak not only about US.)

[kerbiloid]

1948 article

https://forums.spacebattles.com/threads/invasion-base-on-the-moon.331069/

The Lunar Race real beginning and aim.

https://warspot-ru.translate.goog/15171-zavoevanie-luny?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru

Edited December 8, 2021 by kerbiloid

[DDE]

5 hours ago, K^2 said:

No. You don't want batteries in your ion drive engine.

A caveat is that they (or, more specifically, MPDs) have still been used with batteries. Granted the Kren family of experiments only succeeded in producing a plasma cloak, not actually getting the spacecraft somewhere else.