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Japan maglev train breaks world speed record again

bbc.co.uk

131–140 of 170 posts

Re: Japan maglev train breaks world speed record again

#131
post #14

Amazing. Writing this from Berlin, which doesn't have maglev trains, but has phenomenal public transit. It's sad to be going back to the US soon where the infrastructure is so primitive.

Don't be such an idiot. I get it, you enjoy European infrastructure and social democracy. Remember though that you will pay half of the taxes you pay in Germany ... oh, did you just enjoy all the benefits of German infrastructure and society without actually paying any taxes, let alone your whole life? No one is keeping you from remaining in Germany, are they? I can guarantee you they will approve your work permit an…

> Don't be such an idiot.

Please don't post such things here.

Re: Japan maglev train breaks world speed record again

#132

Earlier quoted context omitted.

Almost certainly a spectral analyzer. Shine a light through it, see what the chemical signature is.

That certainly won't work for my aluminum water bottle. Granted, neither do X-rays, and yet I've never had it even questioned going through security.

Yes, I was assuming a typical disposable transparent plastic or glass bottle. I have not seen the machine in question, so I am guessing, but it would be very easy to implement and cover the majority of cases.

Re: Japan maglev train breaks world speed record again

#133
post #121

I wonder if we'll ever get back to "High Speed Air" in my lifetime. Back in the 70s, you could rock up at the airport twenty minutes before your flight left, jump on with minimal hassle, and cruise along at 600mph to your destination. Now, you need to endure two hours of having your fingernail clippers confiscated so that you can fly at 500mph to save on fuel costs. That seems to be the true advantage of rail travel.…

Just flew out of Boston this morning and was through security in under 5 minutes including the TSA pat-down due to opting out of the scanner. Watched a woman who I was with on the way to the airport make it through even faster as she got to security In fact, the last several times I've flown security has generally been under 10 mins. SFO is typically the slowest and most highly variable for me, but at its worst I don…

Flying out of Boston was nice the one time I did it. Security was fast and polite. I think I showed up with 35 minutes to spare and I just made it to my flight.

Re: Japan maglev train breaks world speed record again

#134
post #49

Earlier quoted context omitted.

Are you sure? I'm not finding anything about this. The TGV record is about half the speed of sound, which means the wheel rims are bordering on supersonic, so it's not a simple thing to talk about exceeding it.

Why would the wheel rims rotate at twice the speed of the train? If the train advanced along the track 1m, surely the part of the wheel in contact with the track must also have moved 1m?

I think the idea is that the top of the wheel is basically super sonic compared to the ground. This has to be the case: the train is connected to the middle of the wheel at speed, the bottom of the wheel is going 0 so long as it's not slipping, so the top of the wheel is screaming along at near-sonic speeds.

It's an odd diagram to draw out, as that result is pretty counter-intuitive.

Re: Japan maglev train breaks world speed record again

#135

Amazing. Writing this from Berlin, which doesn't have maglev trains, but has phenomenal public transit. It's sad to be going back to the US soon where the infrastructure is so primitive.

It's easy to call other rail infrastructures "primitive" when your baseline is Berlin to Munich. The US eastern seaboard handles those routes well too. Rail doesn't do so well when you need NYC to Chicago (~800 miles).

Re: Japan maglev train breaks world speed record again

#136

Earlier quoted context omitted.

"the wheel rims were close to supersonic" This doesn't make any sense. The record is around 575 km/h. The speed of sound is 1225km/h. How would the wheel rim be travelling faster than the train? The while rim rotates 1m for every 1m the train travels, surely? Can you explain what you mean?

The top of the wheel is moving faster than the train. If the contact point between the wheel and rail is not slipping, the relative velocity between the wheel at that point and the rail is 0. To maintain that condition, the top of the wheel has to travel at twice the speed of the train. Imagine a point on the wheel. Each time the train moves ones circumference forward, that point also makes a circular trip of 1 circu…

Your link follows to a pretty good set of animations on the topic (linked by the OP of that thread):

http://www.animations.physics.unsw.edu.au//jw/rolling.htm

Good stuff, and even has an interesting note about how train wheel rims acually go backwards as the wheel turns!

Re: Japan maglev train breaks world speed record again

#137
post #42

Earlier quoted context omitted.

That still exists outside the US. Last year I took a flight from germany to a conference in poland and strolled through the airport after checking in. I left the security zone by accident - simply walking through a pair of sliding doors which only open from one side - 10 minutes before departure. But it wasn't a big problem, I simply went through the metal detector/xrays for hand luggage and arrived at the gate with…

as someone who has taken a few hundred flights outside the US in the last years: people get to take their shoes off quite often, but mostly boots and worker's shoes, not sneakers. Sometimes they also ask you to take off a hoodie or such clothing, of course your belt, put your laptop separately from the rest, get an occasional pat down, and the liquid restrictions ("don't take that mysterious bottle in here, but your…

I think it's a function of the airport itself. I have been to Qatar and the security was as simple as sliding my bag in. I didn't have to remove my belt, watch, or phone.

Total time to pass security: 2 minutes.

Total time to pass immigration: 15 minutes. (depends on traffic).

I remember a friend who caught her flight just 10 minutes before gates closed. She made it.

Edit: HaHa. Forgot my local airport. I can get from the entry door, to the Airplane bus in 2 minutes (security + immigration + walking). It usually only have 1 or 2 flights per day and feels very friendly.

Re: Japan maglev train breaks world speed record again

#138
post #16

Amazing. Writing this from Berlin, which doesn't have maglev trains, but has phenomenal public transit. It's sad to be going back to the US soon where the infrastructure is so primitive.

If you look at Washington DC's metro its pretty much the same QoS as you get off the Berlin metro. So I am not quite sure how its considered "primitive" Berlin - 4 - 5 minute trains DC - 6 minute trains Berlin - 9 lines, 170 stations DC - 6 lines, 91 stations and thats not even the biggest metro system in the US. So really the problem isn't going back to the US, its going back to whatever place you're going to in the…

the QoS parameter should also include

1. cleanliness 2. how much stinky the seats are 3. how much greasy/sticky the platforms are etc.

and yes, I am talking about WMATA

Re: Japan maglev train breaks world speed record again

#139

Earlier quoted context omitted.

> Sadly, I bet the way we'll end up equalizing this will be that somebody will eventually bomb a TGV and we'll have to start doing the two hour confiscate-your-kids'-apple-juice routine at the train station too. It would be easier to economically restructure passenger rail cars so that you had independent bomb resistant compartments. Trains have the disadvantage, in contrast with planes, that you can bomb the rails t…

Another thing to note is that it's just a lot harder to cause as much damage to a train. The deadliest Amtrak accidents involved collapsed bridges over water. Derailments or even head-on collisions almost always involve a dozen or less, often zero, fatalities.

Much of this is a function of potential and kinetic energy. High speed trains are going to have more kinetic energy, and therefore more potential for fatality.

Re: Japan maglev train breaks world speed record again

#140
post #6

Amazing. Writing this from Berlin, which doesn't have maglev trains, but has phenomenal public transit. It's sad to be going back to the US soon where the infrastructure is so primitive.

Agreed. The current incarnation of the US transportation system is also downright unsustainable from a fuel and carbon standpoint, and will lead to various downfalls if something isn't done about it. As much as I'm a public transportation advocate (I don't own a car, and refuse car rides if a public transportation option is available for the place I need to get to), it's becoming increasingly more difficult to promot…

The real issue with automobiles and cities isn't so much the cars as the parking.

Parking takes up a huge proportion of urban land and street space that could be used for exclusive bus lanes. Parking requirements makes the building blocks of classic urban neighborhoods, like townhouses, small apartment buildings, and storefronts with apartments above, illegal to build. Using land for parking vastly increases the distance between destinations, making walking impractical. When walking is impractical, transit systems become ineffective because there are too few homes or destinations near them for them to have customers.

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