China Solves 'Tunnel Boom' Problem With Maglev Trains (theguardian.com) 61
Ancient Slashdot reader Epeeist shares a report from The Guardian: The newest version of the maglev train is capable of traveling at 600km/h (about 370mph). However, the train's engineers have wrestled with the problem of the shock waves which occur as the train exits the mouth of a tunnel. When a high-speed train enters an enclosed space such as a tunnel, air in front is compressed, like in a piston. The resulting fluctuations in air pressure coalesce at the tunnel mouth, generating low-frequency shock waves. These are colloquially known as a "tunnel boom" -- a related, albeit different phenomenon to the "sonic boom" heard as aircraft pass the speed of sound. Tunnel booms pose serious challenges to operational safety, as the shock waves can disturb humans and animals nearby, as well as causing structural damage.
Now, however, researchers have discovered that placing innovative soundproofing buffers at tunnel mouths can reduce shock waves by up to 96%. This promises improvements in operational safety, noise pollution and passenger comfort, as well as safeguarding animals in the vicinity of future lines. [...] The porous structure of the new 100-meter long buffers, combined with porous coatings on the tunnel body, allow the trapped air to escape before the train reaches the tunnel mouth, suppressing the boom in the same way as a silencer fitted to a firearm.
Now, however, researchers have discovered that placing innovative soundproofing buffers at tunnel mouths can reduce shock waves by up to 96%. This promises improvements in operational safety, noise pollution and passenger comfort, as well as safeguarding animals in the vicinity of future lines. [...] The porous structure of the new 100-meter long buffers, combined with porous coatings on the tunnel body, allow the trapped air to escape before the train reaches the tunnel mouth, suppressing the boom in the same way as a silencer fitted to a firearm.
Makes sense (Score:5, Interesting)
Bullet silencer technology applied to a bullet train. Makes sense.
Too bad the article lacks images though.
Contemporary Shinkansen trains reduce tunnel boom by elongated noses, inspired by the beaks of birds who can dive from the air into water without causing ripples on the surface.
Re:Makes sense (Score:5, Informative)
It must be more than just the gun silencer concept, because the Japanese tried that with limited success for their conventional high speed trains.
The Chinese seem to have applied some new materials to absorb the sound.
The Japanese must be quite worried about developments in China. Theirs was going to be the only long distance maglev system, and a lot of the financing was based on being able to export the technology. China is going to beat them to deployment and will doubtless export the technology too. Now it sounds like they have solved the only big outstanding issue.
The two systems have some interesting differences. The Japanese trains need wheels below 90 kph, but are simpler and passively safe in the event of total power loss or violent earthquakes. The Chinese trains require active management of the magnetic fields constantly, but float even when not moving.
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As these are current problems here, Im wondering how those will be mitigated without elevating the entire system.
I, personally, would prefer the Japanese version, as safety is better. And its not like tunnel sound is specific to one train track or levitation style.
So mix and match seems best.
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The Japanese and Chinese tracks are all grade separated. I wouldn't be surprised if the entire Chinese network had CCTV with AI to detect objects entering the track. Japan might have some solution for that too, given the speeds involved.
90% of the Japanese system is tunnels through mountains, so very difficult for people to access, and easy to monitor the few entrances.
The human body isn't much of a threat to trains, and the tracks are designed so that vehicles won't be able to get onto them.
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90% of the Japanese system is tunnels through mountains,
I have no idea where you got this idea, but it's definitely not true. There are a lot of tunnels, but most of it is in the open. They have heavy barbed wire protecting the tracks.
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I'm talking specifically about the Chuo Shinkansen, the new maglev one. Most of the conventional lines are not tunnel, although they are all grade separated. No crossings anywhere.
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The Japanese and Chinese tracks are all grade separated
Japan has some grade crossings on local lines, such as Shinsen on the Tokyo Inokashira line. All Shinkansen lines are grade separated.
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I know, I was talking only about high speed rail. There are many, many grade crossings on non high speed lines.
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We need to eliminate at-grade crossings in the US. They're stupid and, unfortunately, there are too many entitled jerks in the US who believe they have some God-given right to go around the barriers, with disastrous results. Even without the jerks, truck drivers misjudging crossing lengths or even crossing heights is one example of why they're a bad idea.
Railroads need to ban the creation of new at-grade crossings. If governments want to cross railroads, they need to build bridges or tunnels. Yes, it's more
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So there are lots of breathless stories coming out of China from different groups, intending to show that they've done good work with the funding they've been given, and hoping to get an increase in funding for the next five years. It's not intended to be informative or even revolutionary.
Normal bureaucracy stuff.
Re:Makes sense (Score:4, Insightful)
Bullet silencer technology applied to a bullet train.
Meanwhile, we're still struggling to bring our rail system into the twentieth century. We might go from diesel to electric in the 2040s.
Re: Makes sense (Score:2)
It's often better to not be first. Like places in Africa that skipped over POTS lines and went straight to mobile. No matter what technology we had, there are some structural reasons trains would have limited success in the U.S. No need to be at the cutting edge on such things before we solve the legal and cultural hurdles.
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When dictators lead in innovation (Score:2)
Re:When dictators lead in innovation (Score:5, Interesting)
People have been touting China as the next world leader, displacing the US, since the 90s. Earlier possibly.
They thought it would happen economically and we all would start learning the communist ways.
What I think is more likely to happen is that China will see major societal turmoil in the next two decades, toppling the authoritarian government and then it will become the land of the free and the home of the brave.
Meanwhile the complacent west will go through a phase of relearning the value of what it used to have. It will do us a lot of good and it'll prime us to take world leader role at a later date... But it will be painful as valuable lessons usually are.
Re:When dictators lead in innovation (Score:5, Informative)
The idea that the population and resources of China will make it a world leader as soon as it reaches enough technology, is the main thesis of the essay "When China awakes, the world will tremble" (Alain Peyrefitte, 1973). Though it sold 800k copies in the original French, this particular essay was apparently not translated. [His later work The Immobile Empire (1989), more critic against China, was read in numerous countries.]
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While interesting as far as factoids go, I'm not sure what you think the impact on my take on matters would be.
I don't think that China's limitation is technology. The whole world is already dependent on its workforce and resources.
China is what enables tech bros to shine. Hell, how many of our scientists are Chinese born bringing with them Chinese work ethics.... and Chinese ethics?
The latter is the issue. Nobody trusts China and for damn good reason. If China manages to ease up and become a high trust soc
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While interesting as far as factoids go, I'm not sure what you think the impact on my take on matters would be.
It was essentially a factoid. You argued China is seen as the next world leader since the 90s, I mention that this had been speculated by one clever person in the 70s. The premise was that China only needed technology, which in the meantime they acquired, explaining why our discussion is happening right now.
Regarding your new arguments, in my view as a simple person, "high trust" is a vowed priority of the Chinese government. China does exactly what it says it wants to do (in the matters relevant to countri
Re:When dictators lead in innovation (Score:5, Insightful)
The latter is the issue. Nobody trusts China and for damn good reason. If China manages to ease up and become a high trust society (which it isn't. As far as I am aware the studies declaring China one are based on questionnaires inside the respective countries and that's worth zilch), stop burning out its youth and still retain some of that work ethic, they won't have to take leadership away from the US, the world will just shimmy a few degrees due China over a few years and it'll be a done deal.
Just who are you placing trust in these days?
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Roman Storm, Elizabeth Holmes, Sam Bankman-Fried.
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Establing
Re:When dictators lead in innovation (Score:4, Interesting)
But I am not talking about outgrowing the economy. Simple dollar values are hollow. China already is totally entrenched in just about every supply chain.
Intel is dying both on the planning and production side of chips. The latter is in Taiwan's hand. If China pulls its head out of its arse, the animosity between it and Taiwan may go up in smoke faster than people want to believe and what then?
As I said elsewhere, if China manages to convince the world it's turning into a high trust society while America is devolving into a lower trust one, well...
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When you have Trump trying hard to destroy the USA(no matter what nonsense he may say to his supporters, the rest of the world see him for what he is, a wannabe dictator), it's no wonder the USA is going downhill.
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Meanwhile the complacent west will go through a phase of relearning the value of what it used to have. It will do us a lot of good and it'll prime us to take world leader role at a later date
You are speculating, and I will speculate even further. If there is a Western renaissance, it will be without the US. Reading the international papers, it is apparent that the US is now regarded as unreliable and a dubious ally. Other alliances are being formed, and other trading partnerships, and there are discussions going on about reducing the reliance on the US.
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Well the words "What I think is more likely to happen" both flag my post as speculation and a personal opinion.
And I agree with you. Since we've given the US quasi leadership of the western world, it giving up world dominance automatically means we as its sycophants won't have a pole position to take over, especially since the same societal issues ail us as do them.
That's why I said in the future we may bounce back but in what way I am unable to say. Perhaps it's gonna be the EU or perhaps either France or
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I think China and the EU will replace USA and Russia as the two world superpowers.
UK and Canada will be kind-of part of the EU in much the same way that they were kind-of part of the USA in the post WW2 era.
Re:When dictators lead in innovation (Score:5, Insightful)
"the US is now regarded as unreliable and a dubious ally" This feeling of other nations towards the U.S. will not go away easily. It is clear the American people are easily duped. There was an article on Politico (I think) where the quizzed people outside the U.S. on la Presidenta's claim that the U.S. was a loser in world trade. They pointed out that the U.S. has great median income level, the median means half of the pop. is above and half is below, and it has been steadily rising over the years and due to international trade. So the schtick from la Presidenta is just another of his lies. So now other countries figure than a future U.S. (alleged) president can pull similar scams on Americans to get him/her self elected. The past is just that, past, they will never count on the U.S. again.
To get a perspective on la Presidenta's relationship with numbers, Michael Wolff, who did a lot research on la Presidenta for his books, says that people who know him think it bizarre that he cannot read a spreadsheet. Put crudely, he's innumerate. He can grok one number being bigger than another but that is about it. And now he's using that genius "knowledge" to bet the entire U.S. economy on economic falsehoods; there's no fixing stupid.
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I don't want them to shift toward the west.
I said I expect them to become a high trust society. While I am personally convinced that we were a high trust society in most parts due to the catholic Church, I would not discount the chance that other cultures can build one as well.
I would also not discount the chance that Catholicism actually ticks up in China at some point. Again, I wouldn't wager on the precise mechanisms... I'm just saying that the instability that is becoming ever more aparent in China CAN
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The Catholic Church is responsible for our high trust society and Catholicism is just waiting to take off in China? Someone has been drinking too much communion wine and needs get out of their church social circles.
Re: When dictators lead in innovation (Score:3, Insightful)
Maybe it is more complicated than what we were taught. Especially with one country going full speed nazi... again.
Stick with trouble...
Re: When dictators lead in innovation (Score:2)
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What makes you say Germany is going full speed Nazi again?
Masked men rounding up "undesirables" into camps?
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Now the USA is going full Nazi indeed, but that is not "going again"
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Re: When dictators lead in innovation (Score:2)
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The underlying assumption is that a people's desire for freedom will always win out.
There seems to be a non-zero chance that present-day China has managed to find the thin edge where their people have just enough freedom to not get grumbly.
It's not impossible that this is not actually true, but it might only fall apart in a hundred years or so.
Re:When dictators lead in innovation (Score:5, Insightful)
A lot of young people are disillusioned with capitalism, and quite understandably so. It hasn't delivered the benefits for them, and the advice they were giving about making it work (get educated, get a house, work hard and rewards will come) turned out to be bad.
They look at China, which provides for citizens. When they see that people are going to migrate to cities, they build big new cities with affordable housing and excellent public transport. Meanwhile in the West it's all landlords, who are also NIMBYs in case you had any ideas about easing the supply issues.
Climate change is another example. There is no reasonable metric by which China is not doing far, far more than Western countries are.
I'm not saying that the Chinese model is better necessarily. Aspects of it are, mostly the ones shared with social democracies like some European countries have. The big issue is that the model many Western countries use is failing badly, and politicians are mostly only offering more pain in response to it.
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I think it's pretty unarguable that China has lifted hundreds of millions out of poverty and into a fairly Western/modern lifestyle.
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People have been touting China as the next world leader, displacing the US, since the 90s. Earlier possibly.
They thought it would happen economically and we all would start learning the communist ways.
What I think is more likely to happen is that China will see major societal turmoil in the next two decades, toppling the authoritarian government and then it will become the land of the free and the home of the brave.
Meanwhile the complacent west will go through a phase of relearning the value of what it used to have. It will do us a lot of good and it'll prime us to take world leader role at a later date... But it will be painful as valuable lessons usually are.
We'll never learn communist ways. The people who advocate for universal health care, UBI etc are delusional.
We're moving further away from it. Even our medicaid and food stamps recipients are now require to submit proof of work rather than just lack of income. We will go more capitalist and we will privatize more government land and drill baby drill.
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People have been touting China as the next world leader, displacing the US, since the 90s. Earlier possibly.
They thought it would happen economically and we all would start learning the communist ways.
What I think is more likely to happen is that China will see major societal turmoil in the next two decades, toppling the authoritarian government and then it will become the land of the free and the home of the brave.
Meanwhile the complacent west will go through a phase of relearning the value of what it used to have. It will do us a lot of good and it'll prime us to take world leader role at a later date... But it will be painful as valuable lessons usually are.
People have been predicting that since the 90's. The liberalisation of China, democratising from the ground up (first in local government, then state, finally federal) piece by piece. Unrest and turmoil, all that stuff. It still hasn't happened.
One thing China is good at, it's heading off dissent at the pass. I doubt we're going to see another Tiananmen Square (I believe the locals refer to it by it's date rather than location, 4 July Incident or some such) because they've learned that it's easier and mo
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How I remember it is closer to the opposite - people supported trade with China with t
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Re: When dictators lead in innovation (Score:2)
Japanese solution. (Also, fans?) (Score:4, Informative)
Japanese solution -- I saw a YouTube video on how the Japanese addressed this by elongating the nose of the Shinkansen. That design was inspired by the kingfisher bird diving in water. The length of the nose helps to gradually displace the air as it enters the tunnel, reducing the strength of the pressure wave.
Also, perhaps fans could be a solution. Powerful blowers that push air out one end of the tunnel, just as the train enters in at the other end, then taper to zero as the train exits
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This is maglev, not train. That is the main reason why it is even a problem. High-speed trains and tunnels are a well understood combination.
They must have stolen that somewhere! (Score:2)
Right? Right? Now, who else has high-speed maglev trains? Anybody?
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It's developed from experience with the Shanghai Maglev, which uses technology from Siemens. It isn't really "stolen" in any sense, and the basic underlying technology is decades old and well-understood. The challenge has been scaling it up for systems beyond a single short route.
3-cheers for the CCP (Score:1)
Good News Day (Score:2)
I like how we have cool engineering and cool computer science posts today instead of just legal battles, doomer gloom, and political intrigue.