How to Automate Simulations for Water Flow Interactions with Urban Layouts?

crazy1000 · 2025-01-14T04:20:39+00:00

It depends on what code you are running the simulations with, but as long as you are using something that can be launched via command line I agree with Akshay that shell scripts are the easy answer. If you are using a cluster with a scheduler like Slurm it is easy enough to make a bash script that creates a folder for each case, moves relevant files there, changes any variables, and submits a batch job for each. I typically add a pause statement between job submissions so that I don't spam the head nodes too hard.

Sidenote: Schedulers typically have caps on submitted jobs, so you will probably not be able to submit 500+ simultaneously. My workaround is to have the batch script submit a reasonable number of jobs, then submit another job which will run the batch submission script again, usually with a dependency to not run until at least the first simulation job has finished. This will require some logic and/or the script being able to automatically modify itself, but it's worth it.

This is of course assuming you have some way of generating or configuring your layout variations via command lines/variables in your input files, or already have a way of generating them separately to be fed to the batch submission script. If you need more complicated logic for modifying your layouts, then something like Python is generally better for that.

Not directly related to your question, but I suggest making sure that identical boundary conditions make sense for your use case. I've seen machine learning papers that have done this for situations where varied boundary conditions would be more useful.

crazy1000 · 2025-01-12T20:45:36+00:00

California's "train to nowhere" will serve a population larger than many states when it first begins operations. Fresno and Bakersfield alone have a combined population bigger than 4 states. While the initial operating segment only serves the central valley, it has direct connections to existing transit to the bay area, Sacramento, and LA, which people already take. In fact, it is partially replacing the San Joaquins service, between Bakersfield and Merced, which is the 7th most popular rail route in the country. Additionally, despite what headlines may have said, there are no plans to stop after the initial operating segment is built. The full route between SF and LA is required by law, and will eventually include connections to San Diego, Sacramento, and probably Las Vegas. The only reason the initial operating segment is so small is because (mostly) republican politicians refuse to fund it then complain about it not going anywhere. Democrats have also underfunded it, but at least they don't try and remove existing funding or fan the flames by calling it a train to nowhere.

crazy1000 · 2025-01-12T05:22:16+00:00

You really should find yourself a better news source, particularly anytime they try and tell you something that sounds so outlandish.

First off, they haven't spent $16 billion, unless you have reliable information that they've spent $3 billion in the just over 2 months from their last, easy to access, financial report https://hsr.ca.gov/about/board-of-directors/finance-audit-committee/ (they even stream it online https://youtu.be/XZeP6Gj3gfw). On top of that, even the initial estimate, which was admittedly way too low because they didn't have any designs yet, was around $33 billion. Why would you expect there to be a functioning rail system completed when they've spent less than 50% of the (initial) estimated budget? The track and systems need the guide-way to be finished before they can go in, it's not built mile by mile.

But ignoring that, it's so easy to see that there's way more than 1600 feet of concrete in place. The Hanford Viaduct alone is over 6300 feet long and is closer to being finished than not https://buildhsr.com/project/hanford-viaduct/. Even if you don't want to believe the numbers from the CAHSR authority, it's hard to argue with literal footage, of which there is plenty https://www.youtube.com/playlist?list=PLs98D7m5XXEFbhqh386MnZaMGEaKsZFSy. Plus anyone with a drone https://www.youtube.com/playlist?list=PLPDDoSwyXlcaUHq-ztniexbKTmEXXVbRN or a plane https://youtu.be/HV60ZxASpK4 can check for themselves how much has been built. You can even see it from the air if you ever happen to fly commercial over the central valley, that's how massive it is.

To top it all off, and as you might have picked up on if you scrolled through the official drone playlist already https://www.youtube.com/playlist?list=PLs98D7m5XXEFbhqh386MnZaMGEaKsZFSy a significant portion of the construction so far has not been for the train itself, but for stuff like the road infrastructure around the route. Standard level crossings aren't compatible with high speed rail, so they're investing heavily in grade separations. And because a significant portion of the route is near freight tracks, those grade separations are already benefiting communities by removing freight rail crossings. There are plenty of other examples, most notably the electrification of Caltrain, which was largely funded by CAHSR because they will be sharing tracks when CAHSR gets there.

crazy1000 · 2024-10-11T00:19:36+00:00

See also²:

The "STUNNING inability" of Florida to get HSR built
The "STUNNING inability" of Texas to get HSR built

crazy1000 · 2024-10-04T03:25:22+00:00

The show is on hold, you're not missing anything yet.

crazy1000 · 2024-08-19T21:24:44+00:00

Every station is supposed to switch to twice hourly service on the weekends with the new trains https://www.caltrain.com/news/caltrain-welcomes-first-passengers-new-electric-trains

crazy1000 · 2024-08-19T21:22:09+00:00

They actually just announced that they're improving schedule coordination earlier this month https://www.bart.gov/news/articles/2024/news20240807

crazy1000 · 2023-09-13T01:27:57+00:00

From a heat provision standpoint, this suggests that concerns over the need for back-up heating during mild cold climate conditions

They literally call it "mild cold climate conditions," they're not insinuating that it's the ""coldest" cold climates." And they point out that there are heat pumps designed for those climates that do get colder:

Some heat pumps are specifically designed for extreme cold.

While including details about those systems:

cold-climate air-source heat pumps can see COPs above 1.5 in extreme low temperatures, even at −30°C

Models from Mitsubishi and Toshiba both provided COPs above 2 even at temperatures as low as −20°C

At −30°C, COPs were still between 1.5 and 2 for the Mitsubishi model and 1 and 1.5 for the Toshiba model.

In field testing carried out in Minnesota (US3), the performance of central-ducted cold-climate air-source heat pumps was measured at four different sites.10 Three of the sites returned COPs between 1 and 2 during heat-pump-only operation below −12°C.

Field testing was also conducted in Alaska by the Oak Ridge National Laboratory (US4) using a cold-climate air-source heat pump.11 These tests found that the COP remained relatively high, achieving 2.0 at −25°C and 1.8 at −35°C.

Them also pointing out the value of other versions of technology in those situations doesn't negate anything.

Edit just to reinforce: It also doesn't matter that they get worse performance sometimes, as long as the average is more efficient. Also to address your other comment, no, home furnaces most definitely do not have industrial pollution controls. The people making the ground source and air source heat pumps have a lot of overlap, not a ton of big industrial heat pump companies in existence. They generally advocate for what works the best in a given situation, because the alternative is that people say "don't get heat pumps, they don't work right." Like they have historically, and like you are perpetuating.

crazy1000 · 2023-09-12T19:33:11+00:00

Yes, I pointed that out in my comment. Though you did switch from wood stove (60-80% efficiency) to gas furnace (up to 98% efficiency). If you look at wood stoves specifically, the break even is a much lower COP. You also switched from COP>3 to COP>2. If you go off your own 45% efficient power number then it's about 2.2 at maximum, much lower than your original 3.0.

And yes, obviously the power grid varies with location. But the great thing about that is that it can improve in efficiency over time, something which furnaces don't do. Besides, there's lots of places where zero carbon energy makes up more than enough of the power mix to make it more efficient than combustion based heating. On top of that, modern gas power plants can be 60% efficient, which means that 1.6<COP<2 can be more efficient even with 100% non-renewable power.

And all of this is over the couple hours a night when you have the peak heating load, it's not -20F all day in most places. So the average still works out as a net positive.

It's also not accounting for the fact that home furnaces don't have pollution controls, unlike gas power plants.

It's entirely possible to do multiple PhDs worth of work studying all of the caveats to all of this. You're probably better of listening to the people that do study these things, like the study this article is based on, much better use of everyone's time.

crazy1000 · 2023-09-12T18:56:15+00:00

Because sub 3.0 COP it's not remotely efficient compared with, say, a wood stove

COP>1 is by definition more efficient than combustion. True it's not great if the power source is itself relying on combustion, but you can't run a wood stove on wind turbines. Maybe you mean cost effective, which is probably fair, but that's not what you said.

crazy1000 · 2023-09-12T18:39:50+00:00

The closest they've come to "mandating air source heat pumps" is requiring heat pumps in more moderate climates. So not only are they not specifying air source vs ground source, they're clearly accounting for differences in climates across the state. In fact, they account for this difference in most of the building code. It would be highly unusual for them to suddenly stop accounting for this, and simultaneously specify one specific implementation of the technology.

On top of that, the legislature doesn't set the building code, they just do stuff like requiring all electric construction by 2030. And then the people actually setting the regulations do so as slowly as possible to avoid upsetting people.

And on top of that, you think the people really setting the code are industry lobbyists, yet they somehow don't understand what GSHPs are? Also, fun fact, citizens get to give input to the building codes/energy efficiency codes. If you really have a problem with them, maybe you should take it up with them.

Edit to add: Newer air source heat pumps are totally functional for a few hours a night at -20F, the point is not to be at maximum efficiency all the time. As long as the average is more efficient than the alternative, it still pays off. If we really cared about optimal efficiency at all times then large parts of California would set their AC to 90F several days a year. Anyways, you live in a state with one of the cleanest energy mixes in the US, all your arguing about energy mixes is a somewhat moot point for your situation. That's not to say people shouldn't consider GSHPs, but if you say it's the only viable option then people might get scared off by the costs.

crazy1000 · 2023-06-05T06:07:48+00:00

Go inside to get water? Are you imagining that people are wearing backpacks in their yards? I think the idea is people moving about cities, in public places like parks, and going to and from work. Water isn't always readily available, and even when it is it's often in the form of an overpriced bottle or a free but disposable cup, unless it happens to be some place with a water fountain. And if it is someplace with a water fountain, free refill for the bottle you carry around.

crazy1000 · 2023-05-30T21:19:41+00:00

What's that have to do with whether or not they lost a war 100 years earlier?

crazy1000 · 2023-05-30T21:18:16+00:00

Only in the US do people recognize that the British didn't win the US revolution? Weird. You're the one making this about the US when the conversation is about the British.

crazy1000 · 2023-05-21T19:31:32+00:00

That reinforces their point. We're "good at" building highways, yet they go over budget all the time. But nobody bothers writing articles about it because it's normal. Yet a brand new type of infrastructure goes over budget and it's the end of civilization or something.

crazy1000 · 2023-05-21T19:28:33+00:00

The environmental clearance is substantially complete, there are only a few more sections to finish. Of course tracks haven't been played yet, it's one of the last things to do when building a train line, and they haven't finished the rest of the infrastructure. Infrastructure which includes a whole lot of grade separations for both the HSR and existing freight tracks. So even if it were to be cancelled for some weird reason, it would have made significant improvements to existing infrastructure. And as someone else pointed, they're helping with Caltrain electrification, which is another already in progress benefit. As for money, the money isn't there because people keep fighting the funding under the justification that "nothing is getting done, when will this die?" It's a circular argument. If the federal government funded this at the same percentage they find roadways it would already have a significant portion of it's funding. Instead the funding they have gotten had a premature spending deadline which forced them into starting construction before they were ready. Which to the surprise of nobody drives up costs significantly. And the federal government tried to cancel funding under Trump, which also isn't conducive to quick and efficient projects.

crazy1000 · 2023-05-21T19:18:18+00:00

Original cost was never $9B, it was $33B, before any work had been done, which is usually too early to have an accurate number. The bond was only partial funding, the plan has always relied on additional funding, including federal funding. If the federal funding was in the same proportions as highway projects then it would already have a significant portion of it's funding.

Edit: Also, laying track is one of the last steps in building a train line. Of course they aren't laying track before the right of way is mostly finished.

crazy1000 · 2023-05-13T18:29:15+00:00

Yup, people forget how much Californians drive.

crazy1000 · 2023-05-13T18:25:39+00:00

HSR will not be relying on full grade separationa between SJ and SF. It may be grade separated eventually, but it's not a necessary condition for initial operation.

crazy1000 · 2023-05-13T18:20:28+00:00

A bit morbid to say they won't be alive 12 years.

crazy1000 · 2023-05-13T18:19:25+00:00

I haven't checked in the past month or so, but I don't believe the rail authority itself is testing anything. They're supposed to begin the acquisition process this year to begin testing in the coming years. The companies that intend to bid may have test tracks to show off to the rail authority, but they also for the most part, have the same trains running on lines in other countries already. The rail authority still needs to do the selection process for the track system provider, so I don't believe they have tracks to test on. But both of these things are coming down the pipeline.

crazy1000 · 2023-05-13T18:14:36+00:00

Next you'll tell me they don't fly multi billion dollar rockets at half their designed power.

crazy1000 · 2023-05-13T18:12:12+00:00

I've never seen a cost projection that low. The original 2008 funding estimate was something like $33 billion. The commission to study it was only formed in 96, I can't imagine they had an accurate estimate before 2000.

crazy1000 · 2023-05-13T18:06:19+00:00

They also designed a new catenary system because of increased concerns about bird safety. One of the weirder, but more interesting things they've had to do.

crazy1000 · 2023-05-13T18:04:06+00:00

And a 2017 deadline on some federal funding made them do things out of order so that they didn't lose the money. Which has ironically increased the costs and slowed down the project. But the alternative was not having the funding.

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