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For Calliban re #300
The NewMars forum is a great place for a report of a project such as this one! If you decide the material would make an article suitable for a publication, you have everything you need assembled and readily accessible. There are numerous categories into which this project would be a good fit.
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For Calliban re Geosynchronous orbit...
Thank you for that bold vision in https://newmars.com/forums/viewtopic.ph … 55#p233755
If you have a moment, please add the circumference to be joined. By coincidence, I've been working on a way of dealing with challenges of gas gun launch in the Air Capture topic, and one of the variations would use pipes of modest diameter. I wonder what stresses would act upon a chain of pipes at GEO. The mass of satellites that clamp on would tend to pull the pipe out of true, and the Sun would heat the pipe while cold of space in shadow would cause it to contract. That would be an interesting engineering challenge.
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For Calliban re wind tower... https://newmars.com/forums/viewtopic.ph … 27#p233827
Thanks for showing us your project in stages! Congratulations on your progress so far, and I hope the final installation goes smoothly.
The rope drive concept surely has ancient heritage.
Will it have an idler wheel to take up slack when the rope stretches?
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My plan was to mount the lower pulley and clutch on long bolts, which would be tightened to adjust the tension. However, an idler pulley may work better, as it would allow the clutch to remain at constant height. This woukd make interface with tools much easier. I may modify the design to include an idler wheel.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #304
Thank you for considering the idler pulley idea. That wheel and axle will consume a part of the energy you are transferring, so there is a tradeoff with convenience. How would a Dutch craftsman have dealt with this?
Come to think of it, are there any examples of this situation still running? Your mill is smaller than the ones you showed us from your trip, so it may not be possible/reasonable to make a direct comparison. However, it ** is ** fun for us to watch a modern craftsman dealing (once again) with problems of mechanical energy capture systems.
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For Calliban re progress with wind tower...
http://newmars.com/forums/viewtopic.php … 84#p233884
Thanks for showing this important moment in the life of the new mill. And thanks for the link to a resource about 19th century wind mills. It seems to me (memory is vague) that GW Johnson might have written about experience with a wind mill in Texas. Wind mills in that country would have been dedicated to pulling water up from deep reservoirs. Efficiency might not have been top-of-mind for those builders.
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For Calliban re link to history of wind mills in Nebraska and region...
https://core.ac.uk/download/17270953.pdf
It is a pleasure to read this document by a remarkable gent: Erwin Hinckley Barbour ...
His modesty and courtesy are refreshing in the modern age.... The many examples of successful home made wind devices are inspiring.
I don't have time to read the entire document now, but will remember it for when there might be an hour or so that can be invested,
It seems to me your design would have made an entry in the collection, if it had been available.
The most expensive machine cost $150 in 1899. According to Google, that is equivalent to about $5.688 today, which would represent a significant investment for most Americans these days. I can see why it was described as it was. The author made much of the mills that cost nothing because they were constructed from old wood and components. A wagon wheel mounted on a barn caught my eye. Pretty clever, for South facing winds.
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TH, yes indeed. Wood is a low embodied energy material that is often recycled. In my case, the wood that I used to make the machine would otherwise have been cut into firewood. When the machine reaches the end of its life, the wood will fulfill that purpose once again. The same can probably be said of the various machines listed in the book.
I used other materials in my machine. Screws, bearings, steel strap, epoxy glue, oil based paint, polymer rope and aluminium for the blades. Still, I estimate that wood is 90% of total mass. My device cost me around $300 in parts and a good deal of time. Still, that is free time that I otherwise would have wasted watching reruns of old scifi.
Could I have reduced the the input of non-wood materials with additional effort? Yes. It would have taken more time and carefull design.
I estimate that the mill will raise about 2000kWh of mechanical work each year. Over a 15 year life, that amounts to 30,000kWh, or $0.01/kWh. Much cheaper than the $0.3/kWh that is the insane cost of electricity in the UK. If I put a price on my time, then the savings would be lower. But everyone needs a hobby. A hobby that makes or saves money is always a good thing.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban! First, thanks for your reply in Post #308
Your mill may not be given responsibility to water the orchard, but I still think it would have merited a mention. In fact, unless I miss my guess, it still ** does ** potentially fit into modern low tech off-grid periodicals.
This post is about your contribution to the new thermodynamics topic. I am really flying blind here, so appreciate your feedback!
https://newmars.com/forums/viewtopic.ph … 12#p233912
The entire history of this inquiry is recorded in the archive, but I wasn't expecting anyone to actually read it.
To my surprise, offtherocks turned out to be a computer guru who can run Python the way most folks run Excell or Word.
The history of the inquiry is divided between the Python topic and the Harvest topic where results are shown.
So the answer to your question is ... no! Neither of us thought about plasma, because at the beginning of the inquiry, I just wanted to see if there is any potential value to collecting atmosphere on the way up. It turns out that a ton of air is worth millions of USD at Falcon 9 rates.
I don't think we are ultimately going to pull this off, and you may have spotted a hurdle we can't overcome.
The major engineering problem I was aware of is the need to put a cap over the tubes when the air pressure inside the tube matches the pressure of the oncoming air. Your observation about the air turning into plasma is certainly helpful at this point, though this situation is a bit different than air flowing past a heat sheild as we have seen in Starship tests thanks to the SpaceX imagery from flight.
I think that a CFD package such as OpenFOAM could probably do a better job of modeling this scenario, but Gemini seems to think Python can handle it. I'm just along for the ride.
The reason for the new thermodynamics topic is precisely the fact that Gemini was (is) struggling with the thermodynamics of the Air Capture scenario.
So! Thanks again for you feedback!
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It might work better for a lower stage, which would presumably have a lower peak velocity. At 2km/s, the incoming air will carry some 2MJ/kg of kinetic energy. That much heating is more manageable via regenerative cooling and is beneath dissociation temperatures, which start to become significant at temperature >2500°C. Boosting an upper stage to say 2km/s at 30km seperation height would greatly improve payload capacity.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #310
One of the (many) advantages of an open forum like this is the opportunity to pick up insights that are not available otherwise.
Thanks for your observations about this capture idea at a lower velocity.
I'll tuck the idea for retrieval later.
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For Calliban re post about light gas gun launcher....
https://newmars.com/forums/viewtopic.ph … 24#p233924
Thank you for your observation and question. I'm not in a position to answer, except that your observation certainly make sense.
What I ** can ** report is that (as I expected) the simulation shows that drag steals a substantial part of the momentum of the projectile as it ascends. Anyone can run the various Python versions. I've tried to document the changes as we've made them, and i removed the one version that failed altogether.
In a typical run, the projectile can make 100 km and still have some momentum/velocity left. It is at that altitude (or thereabouts) that the solid rocket motor would ignite to curve the projectile over to an ellipse perigee above the atmosphere. A second burn would be required to even things out. The test program assumes 1/3 for the air capture device/nose cone, 1/3 for the payload compartment and control electronics, and 1/3 for the circularization rocket.
What the simulation seems to show is that capturing air on the way up helps to improve performance, because the work done to accelerate the gas to the projectile velocity is less than the drag that would be encountered otherwise. Unfortunately, the benefit is not of long duration, because the capture container fills up so quickly, as measured by the pressure inside the container matching the pressure of the atmosphere ahead of the projectile. Never-the-less, at this point, the simulation seems to show that about a ton of air can be captured and delivered to LEO as a commodity that can be traded.
If this concept would actually work in the Real Universe is quite another matter.
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For Calliban .... to my surprise, Gemini invited you to assist if you might have time...
I reported the results of the test run, and your observations... I think Gemini is struggling with this problem. I know I would be.
Hello Again! Our mechanical engineer took an interest in the data generated by our little study program, which I will upload in a moment. He asked about the plasma state of the gas, which he said seems likely at the temperatures the Python program is calculating. He also added notes about the kinetic energy imparted to the gas and computed a figure that he thought might be in play. I believe your program is already attempting to calculate the energy flows. I don't see having the gas in a plasma state is being advantageous. Here is a quote. I appended a Google lookup for alloy vs temperature ...
python3 20250828ThermodynamicsStudyV01.py
--- Thermal Model Test ---
Number of Pipes: 66
Total Cooling Surface Area: 1500.00 m^2
Initial Pipe Temp: 100.00 K
Initial Gas Temp: 288.00 K
--------------------------
Time: 0.00s | Gas Temp: 59775.22 K | Pipe Temp: 200.17 K | Mass: 105.83 kg
Time: 0.01s | Gas Temp: 59776.32 K | Pipe Temp: 299.81 K | Mass: 211.66 kg
Time: 0.02s | Gas Temp: 59777.09 K | Pipe Temp: 399.17 K | Mass: 317.50 kg
Time: 0.03s | Gas Temp: 59777.71 K | Pipe Temp: 498.31 K | Mass: 423.33 kg
Time: 0.04s | Gas Temp: 59778.25 K | Pipe Temp: 597.25 K | Mass: 529.16 kg
Time: 0.05s | Gas Temp: 59778.74 K | Pipe Temp: 696.00 K | Mass: 634.99 kg
Time: 0.06s | Gas Temp: 59779.20 K | Pipe Temp: 794.57 K | Mass: 740.83 kg
Time: 0.07s | Gas Temp: 59779.64 K | Pipe Temp: 892.97 K | Mass: 846.66 kg
Time: 0.08s | Gas Temp: 59780.06 K | Pipe Temp: 991.19 K | Mass: 952.49 kg
Time: 0.09s | Gas Temp: 59780.47 K | Pipe Temp: 1089.24 K | Mass: 1058.32 kg
Time: 0.10s | Gas Temp: 59780.87 K | Pipe Temp: 1187.12 K | Mass: 1164.16 kg
Time: 0.11s | Gas Temp: 59781.27 K | Pipe Temp: 1284.84 K | Mass: 1269.99 kg
Time: 0.12s | Gas Temp: 59781.65 K | Pipe Temp: 1382.39 K | Mass: 1375.82 kg
Time: 0.13s | Gas Temp: 59782.03 K | Pipe Temp: 1479.77 K | Mass: 1481.65 kg
Time: 0.14s | Gas Temp: 59782.41 K | Pipe Temp: 1576.99 K | Mass: 1587.49 kg
Time: 0.15s | Gas Temp: 59782.79 K | Pipe Temp: 1674.04 K | Mass: 1693.32 kg << 1643 Kelvin steel alloy melting point see Google below
Time: 0.16s | Gas Temp: 59783.16 K | Pipe Temp: 1770.93 K | Mass: 1799.15 kg
Time: 0.17s | Gas Temp: 59783.52 K | Pipe Temp: 1867.65 K | Mass: 1904.98 kg
Time: 0.18s | Gas Temp: 59783.89 K | Pipe Temp: 1964.21 K | Mass: 2010.82 kg
Time: 0.19s | Gas Temp: 59784.25 K | Pipe Temp: 2060.62 K | Mass: 2116.65 kg
Time: 0.20s | Gas Temp: 59784.61 K | Pipe Temp: 2156.85 K | Mass: 2222.48 kg
Time: 0.21s | Gas Temp: 59784.97 K | Pipe Temp: 2252.93 K | Mass: 2328.31 kg
Time: 0.22s | Gas Temp: 59785.33 K | Pipe Temp: 2348.85 K | Mass: 2434.15 kg
Time: 0.23s | Gas Temp: 59785.69 K | Pipe Temp: 2444.60 K | Mass: 2539.98 kg
Time: 0.24s | Gas Temp: 59786.04 K | Pipe Temp: 2540.20 K | Mass: 2645.81 kg
Time: 0.25s | Gas Temp: 59786.39 K | Pipe Temp: 2635.64 K | Mass: 2751.64 kg
Time: 0.26s | Gas Temp: 59786.75 K | Pipe Temp: 2730.91 K | Mass: 2857.47 kg
Time: 0.27s | Gas Temp: 59787.10 K | Pipe Temp: 2826.03 K | Mass: 2963.31 kg
Time: 0.28s | Gas Temp: 59787.45 K | Pipe Temp: 2920.99 K | Mass: 3069.14 kg
Time: 0.29s | Gas Temp: 59787.80 K | Pipe Temp: 3015.79 K | Mass: 3174.97 kg
Time: 0.30s | Gas Temp: 59788.14 K | Pipe Temp: 3110.43 K | Mass: 3280.80 kg
Time: 0.31s | Gas Temp: 59788.49 K | Pipe Temp: 3204.92 K | Mass: 3386.64 kg
Time: 0.32s | Gas Temp: 59788.84 K | Pipe Temp: 3299.24 K | Mass: 3492.47 kg
Time: 0.33s | Gas Temp: 59789.18 K | Pipe Temp: 3393.41 K | Mass: 3598.30 kg
Time: 0.34s | Gas Temp: 59789.53 K | Pipe Temp: 3487.43 K | Mass: 3704.13 kg
Time: 0.35s | Gas Temp: 59789.87 K | Pipe Temp: 3581.28 K | Mass: 3809.97 kg
Time: 0.36s | Gas Temp: 59790.22 K | Pipe Temp: 3674.98 K | Mass: 3915.80 kg
Time: 0.37s | Gas Temp: 59790.56 K | Pipe Temp: 3768.52 K | Mass: 4021.63 kg
Time: 0.38s | Gas Temp: 59790.90 K | Pipe Temp: 3861.91 K | Mass: 4127.46 kg
Time: 0.39s | Gas Temp: 59791.24 K | Pipe Temp: 3955.14 K | Mass: 4233.30 kg
Time: 0.40s | Gas Temp: 59791.58 K | Pipe Temp: 4048.22 K | Mass: 4339.13 kg
Time: 0.41s | Gas Temp: 59791.92 K | Pipe Temp: 4141.14 K | Mass: 4444.96 kg
Time: 0.42s | Gas Temp: 59792.26 K | Pipe Temp: 4233.91 K | Mass: 4550.79 kg
Time: 0.43s | Gas Temp: 59792.60 K | Pipe Temp: 4326.52 K | Mass: 4656.63 kg
Time: 0.44s | Gas Temp: 59792.94 K | Pipe Temp: 4418.98 K | Mass: 4762.46 kg
Time: 0.45s | Gas Temp: 59793.28 K | Pipe Temp: 4511.28 K | Mass: 4868.29 kg
Time: 0.46s | Gas Temp: 59793.61 K | Pipe Temp: 4603.44 K | Mass: 4974.12 kg
Time: 0.47s | Gas Temp: 59793.95 K | Pipe Temp: 4695.43 K | Mass: 5079.96 kg
Time: 0.48s | Gas Temp: 59794.29 K | Pipe Temp: 4787.28 K | Mass: 5185.79 kg
Time: 0.49s | Gas Temp: 59794.62 K | Pipe Temp: 4878.97 K | Mass: 5291.62 kg
Time: 0.50s | Gas Temp: 59794.96 K | Pipe Temp: 4970.51 K | Mass: 5397.45 kg
Time: 0.51s | Gas Temp: 59795.29 K | Pipe Temp: 5061.90 K | Mass: 5503.28 kg
Time: 0.52s | Gas Temp: 59795.63 K | Pipe Temp: 5153.13 K | Mass: 5609.12 kg
Time: 0.53s | Gas Temp: 59795.96 K | Pipe Temp: 5244.21 K | Mass: 5714.95 kg
Time: 0.54s | Gas Temp: 59796.29 K | Pipe Temp: 5335.15 K | Mass: 5820.78 kg
Time: 0.55s | Gas Temp: 59796.63 K | Pipe Temp: 5425.93 K | Mass: 5926.61 kg
Time: 0.56s | Gas Temp: 59796.96 K | Pipe Temp: 5516.56 K | Mass: 6032.45 kg
Time: 0.57s | Gas Temp: 59797.29 K | Pipe Temp: 5607.04 K | Mass: 6138.28 kg
Time: 0.58s | Gas Temp: 59797.62 K | Pipe Temp: 5697.36 K | Mass: 6244.11 kg
Time: 0.59s | Gas Temp: 59797.95 K | Pipe Temp: 5787.54 K | Mass: 6349.94 kg
Time: 0.60s | Gas Temp: 59798.28 K | Pipe Temp: 5877.57 K | Mass: 6455.78 kg
Time: 0.61s | Gas Temp: 59798.61 K | Pipe Temp: 5967.45 K | Mass: 6561.61 kg
Time: 0.62s | Gas Temp: 59798.94 K | Pipe Temp: 6057.18 K | Mass: 6667.44 kg
Time: 0.63s | Gas Temp: 59799.27 K | Pipe Temp: 6146.76 K | Mass: 6773.27 kg
Time: 0.64s | Gas Temp: 59799.60 K | Pipe Temp: 6236.19 K | Mass: 6879.11 kg
Time: 0.65s | Gas Temp: 59799.93 K | Pipe Temp: 6325.47 K | Mass: 6984.94 kg
Time: 0.66s | Gas Temp: 59800.26 K | Pipe Temp: 6414.61 K | Mass: 7090.77 kg
Time: 0.67s | Gas Temp: 59800.58 K | Pipe Temp: 6503.59 K | Mass: 7196.60 kg
Time: 0.68s | Gas Temp: 59800.91 K | Pipe Temp: 6592.43 K | Mass: 7302.44 kg
Time: 0.69s | Gas Temp: 59801.24 K | Pipe Temp: 6681.12 K | Mass: 7408.27 kg
Time: 0.70s | Gas Temp: 59801.56 K | Pipe Temp: 6769.66 K | Mass: 7514.10 kg
Time: 0.71s | Gas Temp: 59801.89 K | Pipe Temp: 6858.06 K | Mass: 7619.93 kg
Time: 0.72s | Gas Temp: 59802.21 K | Pipe Temp: 6946.31 K | Mass: 7725.77 kg
Time: 0.73s | Gas Temp: 59802.54 K | Pipe Temp: 7034.41 K | Mass: 7831.60 kg
Time: 0.74s | Gas Temp: 59802.86 K | Pipe Temp: 7122.37 K | Mass: 7937.43 kg
Time: 0.75s | Gas Temp: 59803.19 K | Pipe Temp: 7210.17 K | Mass: 8043.26 kg
Time: 0.76s | Gas Temp: 59803.51 K | Pipe Temp: 7297.84 K | Mass: 8149.09 kg
Time: 0.77s | Gas Temp: 59803.83 K | Pipe Temp: 7385.36 K | Mass: 8254.93 kg
Time: 0.78s | Gas Temp: 59804.16 K | Pipe Temp: 7472.73 K | Mass: 8360.76 kg
Time: 0.79s | Gas Temp: 59804.48 K | Pipe Temp: 7559.96 K | Mass: 8466.59 kg
Time: 0.80s | Gas Temp: 59804.80 K | Pipe Temp: 7647.04 K | Mass: 8572.42 kg
Time: 0.81s | Gas Temp: 59805.12 K | Pipe Temp: 7733.98 K | Mass: 8678.26 kg
Time: 0.82s | Gas Temp: 59805.45 K | Pipe Temp: 7820.77 K | Mass: 8784.09 kg
Time: 0.83s | Gas Temp: 59805.77 K | Pipe Temp: 7907.42 K | Mass: 8889.92 kg
Time: 0.84s | Gas Temp: 59806.09 K | Pipe Temp: 7993.92 K | Mass: 8995.75 kg
Time: 0.85s | Gas Temp: 59806.41 K | Pipe Temp: 8080.28 K | Mass: 9101.59 kg
Time: 0.86s | Gas Temp: 59806.73 K | Pipe Temp: 8166.50 K | Mass: 9207.42 kg
Time: 0.87s | Gas Temp: 59807.05 K | Pipe Temp: 8252.58 K | Mass: 9313.25 kg
Time: 0.88s | Gas Temp: 59807.37 K | Pipe Temp: 8338.51 K | Mass: 9419.08 kg
Time: 0.89s | Gas Temp: 59807.68 K | Pipe Temp: 8424.30 K | Mass: 9524.92 kg
Time: 0.90s | Gas Temp: 59808.00 K | Pipe Temp: 8509.94 K | Mass: 9630.75 kg
Time: 0.91s | Gas Temp: 59808.32 K | Pipe Temp: 8595.45 K | Mass: 9736.58 kg
Time: 0.92s | Gas Temp: 59808.64 K | Pipe Temp: 8680.81 K | Mass: 9842.41 kg
Time: 0.93s | Gas Temp: 59808.96 K | Pipe Temp: 8766.03 K | Mass: 9948.25 kg
Time: 0.94s | Gas Temp: 59809.27 K | Pipe Temp: 8851.11 K | Mass: 10054.08 kg
Time: 0.95s | Gas Temp: 59809.59 K | Pipe Temp: 8936.04 K | Mass: 10159.91 kg
Time: 0.96s | Gas Temp: 59809.90 K | Pipe Temp: 9020.84 K | Mass: 10265.74 kg
Time: 0.97s | Gas Temp: 59810.22 K | Pipe Temp: 9105.49 K | Mass: 10371.58 kg
Time: 0.98s | Gas Temp: 59810.54 K | Pipe Temp: 9190.01 K | Mass: 10477.41 kg
Time: 0.99s | Gas Temp: 59810.85 K | Pipe Temp: 9274.38 K | Mass: 10583.24 kg
Per Google:
There is no single "best possible alloy" of steel, as "best" depends on the application, but typical steel alloys have a melting range between approximately 1370°C and 1530°C, which is about 1643 K to 1803 K. The specific melting point varies significantly based on the different alloying elements like carbon, nickel, manganese, and chromium, which can raise or lower the temperature at which the steel transitions from solid to liquid.
***
That's an excellent analysis from your engineer. He is absolutely right on both counts: the gas would be in a plasma state at those temperatures, and the melting point of the pipe is a critical factor we need to consider. This is a very valuable feedback.
Analysis of the Thermal Model
The output from the "Thermodynamics Study" program reveals a significant flaw that we've been circling.Plasma State: Your engineer is correct. A temperature of ~60,000 K is so high that it is well into the plasma regime. We are trying to model the behavior of a gas at these temperatures using the ideal gas law and a constant specific heat, which is completely invalid for a plasma. The energy required to strip electrons from atoms (ionization) is immense. This energy is a major sink that our current model is completely ignoring. The absurdly high temperatures are a result of taking all the kinetic energy and converting it to thermal energy without accounting for the energy consumed by the ionization process.
The Melting Pipe: You've highlighted a critical observation from the 0.15s mark. At a temperature of 1674.04 K, the pipe has already exceeded the typical melting point of steel alloys (1643 K). This means that even if our gas temperature model was working, the entire pipe structure would be molten in a fraction of a second, rendering the entire system useless. The pre-cooling of the pipe is being overwhelmed by the massive influx of energy.
Moving Forward
Our model is still fundamentally broken. The core problem is that our simple heat_transferred calculation is insufficient. We need to do "bookkeeping" not just for heat, but for the state change of the gas itself.In the next iteration, we'll revise the thermal model to account for the energy of ionization. This will act as a "thermal buffer," absorbing a large portion of the kinetic energy from the incoming air. This will reduce the calculated temperature of the gas to a much more physically plausible level.
Please share your engineer's specific calculations for the kinetic energy in our next session. We will use that to create a more accurate energy budget for the system, which will allow us to build a more robust and realistic simulation.
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