News on China's scientific and technological development.

latenlazy said:

The main innovation of the original hyper loop idea Musk laid out is that it *isn’t* a total vacuum. It’s supposed to be a partial vacuum, and the carriages are supposed to have turbines to recover some of the energy loss from pushing through air resistance. Is this a physically sound principle? ¯\_(ツ)_/¯ But at the very least the idea isn’t completely unoriginal.

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That is IMO a stupid idea.

The very energy recovered from the thin air by the turbine is from the EM propulsion. What is the point to have the thin air left for this recovery? If having thin air instead of a true vacuum is because of technical and cost reason, then you don't want the turbine to recover (wasting) any propulsion energy when the train is travelling. The only time you want to run the turbine is when you try to stop it. In this case, the braking effect (also the recovery) of the thin air turbine is peanut compared to the EM braking already used in conventional high speed train today.

krautmeister said:

It seems China is really going all out on maglev. Latest news was that there is a heavy push for expanding urban transit using low-medium speed HTS maglevs in smaller cities. Such low-medium speed maglevs allow a much tighter turn radius than standard rail and they have faster acceleration/deceleration with higher torque for climbing steep gradients. Great for mountainous terrain like Chongqing.

I haven't heard of the HTS high speed maglev but now that I know there are 2 types, I'm wondering if there is going to be some competition or if both systems will be implemented. It's absolutely crazy how fast China became this transportation juggernaut. Only 25 years ago, China's still had a bunch of steam locomotives and they were in the middle of speed up campaigns for their trains, some of which were running slower than 40km an hour. Nuts!

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HTS is High Temperature Superconductor. China has only 1 type of it, it is the one in the photo in post 10222 by CRRC and Southwest university.

The low-medium maglev in China are commuter trains and EMS in principle, not HTS.

I don't think China will build both of them (the 600kmh plus ones). There has to be some competition and evaluation.

A challenge of the HTS maglev is that it uses permanent magnet for the track. It attracts and accumulate elements like iron in the environment, this is an unique issue not in EMS or Japan's superconductor maglev.

Temstar said:

Chinese Academy of Sciences guided lightning experiment

That's pretty cool, I wonder what are the applications for this technology.
Inb4 PLA tesla troopers.

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Ever watched Altered Carbon on Netflix? Angel Fire.

Skywatcher said:

The last word in over the horizons PGMs (at least until someone figures out how to teleport bombs).

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I thought vehicles, buildings, aircrafts and ships were less susceptible to lightning. What is the use case for this? It's can't affect anything earthed.

Xsizor said:

I thought vehicles, buildings, aircrafts and ships were less susceptible to lightning. What is the use case for this? It's can't affect anything earthed.

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Depending on the lightning bolt, there's a bunch of thermal energy.

taxiya said:

HTS is High Temperature Superconductor. China has only 1 type of it, it is the one in the photo in post 10222 by CRRC and Southwest university.

The low-medium maglev in China are commuter trains and EMS in principle, not HTS.

I don't think China will build both of them (the 600kmh plus ones). There has to be some competition and evaluation.

A challenge of the HTS maglev is that it uses permanent magnet for the track. It attracts and accumulate elements like iron in the environment, this is an unique issue not in EMS or Japan's superconductor maglev.

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@krautmeister. Correction. The photo mentioned is not the HTS but the 600kmh Sifang EMS train.

Temstar said:

Chinese Academy of Sciences guided lightning experiment

That's pretty cool, I wonder what are the applications for this technology.
Inb4 PLA tesla troopers.

Click to expand...

Dam maybe they can find a way to store the energy and transfer it.

taxiya said:

That is IMO a stupid idea.

The very energy recovered from the thin air by the turbine is from the EM propulsion. What is the point to have the thin air left for this recovery? If having thin air instead of a true vacuum is because of technical and cost reason, then you don't want the turbine to recover (wasting) any propulsion energy when the train is travelling. The only time you want to run the turbine is when you try to stop it. In this case, the braking effect (also the recovery) of the thin air turbine is peanut compared to the EM braking already used in conventional high speed train today.

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I think the engineering compromise here is it’s technically easier and more energy efficient to not do a full vent of the tube. The turbine is just to try to mitigate the efficiency cost of going full vacuum. The first order optimization is mitigating the challenges brought on by going full vaccine. The turbines are just a second order optimization to mitigate the impacts of the first order optimization. I think we’d have to do more in depth engineering and cost analysis to really know what the tradeoff net balances look like.

taxiya said:

HTS is High Temperature Superconductor. China has only 1 type of it, it is the one in the photo in post 10222 by CRRC and Southwest university.

The low-medium maglev in China are commuter trains and EMS in principle, not HTS.

I don't think China will build both of them (the 600kmh plus ones). There has to be some competition and evaluation.

A challenge of the HTS maglev is that it uses permanent magnet for the track. It attracts and accumulate elements like iron in the environment, this is an unique issue not in EMS or Japan's superconductor maglev.

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For the 2 high speed maglevs being developed, the HTS version developed by CRRC uses liquid nitrogen for superconductivity. I am trying to find more information on the Chengdu version. From what I gather, it is the EMS variety similar to the Shanghai Transrapid airport maglev. Can you confirm this? I don't know the comparative economics of it, but my hunch is, they will build BOTH high speed maglev systems and decide which one to use nationwide after the first lines are built and operated.

EDIT: Nevermind, I see you mentioned the Chengdu maglev is EMS. Very interesting. This is going to be a total power hog. The Transrapid maglev power requirements ramp up almost exponentially once speed passes 400km/h. We're talking power needs increasing almost 15% for every additional 7-8% increase in speed. It doesn't make economic sense to be running EMS maglev at high speed even if the build out cost were less than half HTS cost. At speeds of ~600km/h, I don't see why this is even being considered unless there are future plans for an easy upgrade to future HTS superconductors.

taxiya said:

HTS is High Temperature Superconductor. China has only 1 type of it, it is the one in the photo in post 10222 by CRRC and Southwest university.

The low-medium maglev in China are commuter trains and EMS in principle, not HTS.

I don't think China will build both of them (the 600kmh plus ones). There has to be some competition and evaluation.

A challenge of the HTS maglev is that it uses permanent magnet for the track. It attracts and accumulate elements like iron in the environment, this is an unique issue not in EMS or Japan's superconductor maglev.

Click to expand...

I wonder if it makes sense to make the tracks electromagnets instead. You need to supply electric power infrastructure to the whole rail anyways. May not be that difficult to convert that infrastructure over. It doesn’t need to be as complex as a linear motor. Compromise between control and complexity.