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> The french TGV (the fastest - 515 km/h that's 320 miles per hour)
> is a souped-up ordinary train.

Pretty "ordinary" yes... but there's one striking feature that differs from ordinary trains:

On a normal carriage, you have two boogie wheel pairs, one on each end of the carriage. On the TGV two carriages shares the same boogie in the intersection. Picture here: TGV boogie

This picture is actually from a tilting prototype of the TGV.

You can read more about the modifications to the TGV (Train Grande Vitesse) here, and some history here.

> The french TGV (the fastest - 515 km/h that's 320 miles per hour)
> is a souped-up ordinary train.

Pretty "ordinary" yes... but there's one striking feature that differs from ordinary trains:

On a normal carriage, you have two boogie wheel pairs, one on each end of the carriage. On the TGV two carriages shares the same boogie in the intersection. Picture here: TGV boogie

This picture is actually from a tilting prototype of the TGV.

You can read more about the modifications to the TGV (Train Grande Vitesse) here, and some history here.

The original TGV prototypes used gas turbine engines. See this link.

After you posted the text I read it again. No mention of j002e2 (or j002e3). The object he found was designated 2002BJ2 . With an aphelion of 3.4 and a period of 1071 days, it is definitely not orbiting the Earth.

of Amtrak doing something almost right. The Northeast Corridor is the only profitable route for Amtrak.
This is a good article written on the topic of Amtrak, its 87 VPs, its end of subsidization, and what must be done moving forward.
Everything you ever wanted to know about the Acela

Gamers will be able to download it here.

Here is the speed recording chart of the record.

Maglev is simply too expensive for what it does; unlike the current TGVs and ICEs, it is NOT compatible with the current rail network, so one cannot go high-speed for most of the trip, then go to another town not served by the high-speed line. Maglev is just an excuse to spend lots of money to featherbed unemployed aerospace engineers.

Maglev has also a very big hurdle: the size of the switches, which makes it impractical to put enough on a rail network to make it flexible and efficient enough.

And even if maglev was practical, the higher speeds yield a diminishing return on the gain of time; since to halve the journey time, you have to double the speed, soon enough, the cost of going much faster will outweigh the advantages of doing to.

And then how fast can you go? You clearly can't have a supersonic train, unless you don't mind the reaction of the people who live near the tracks... The only way a maglev can be practical is underground, within an evacuated tunnel; there, the speed limit would be twice the orbital speed at the distance the tunnel is from the center of the earth, which is several orders of magnitude greater than the speed of sound. But to get such performance would call for a level of expenditure several orders of magnitude of what such a high-speed service would be worth.

Erm, incorrect. While the Eurostar incorporates many of the features of the French TGV trains (which are bloody brilliant btw) it's production was an Anglo-French co-operation (like Concorde) and therefore has a hell of a lot of British design and engineering in there too.

Have a look here and here for more info.

When you consider the different rail and power systems the Eurostar is capable of operating on you begin to appreciate just how much of an engineering achievement it is. I mean, come on, a train 1/4 of a mile long (the longest passenger train in the world) capable of traveling at 186mph across the signalling and power systems of 7 different countries!

It's just a pity that the rail infrastructure in the UK can't accomodate high speed services. It travels about 80mph slower in the UK than in France. With Railtrack as cocked up as it is, it doesn't look like that's about to change either (they have the contract for the new high speed line through Kent to London).

Interestingly, the reason the train goes so slowly through Kent (relatively - it's still doing about 100mph) is because if 2 Eurostars were to pass each other on the closely spaced Kent track at full speed (ie a closing speed of 372mph) the resuting pressure wave would blow out the windows on the train!

Link. See the item in 1993.

And that was with a regular train (no funny shit with the wheels, just a long straight railway)

Well, the train was not quite 'regular'. Some modifications were made to the train, including increased power output, bigger wheels and longer gearing, modified pantographs and some aerodynamic mods.

You are right, you need slightly more to cover "standard deviation". If you toss a coin 100 times, it's very rare that you get exactly 50 heads. You may get 40, you may get 60. That's due to standard deviation, but the effect wears off the bigger your sample. So more than 100MB will be necessary, but not substantially more.

If you transmit 100 packets, and expect to receive 20 of them, the chances that you transmitted the right 20 is very very slim. And you absolutely cannot produce a scheme where any 20 will give you the right answer.

Please reread my post. Any 20 are ok, that's the whole point.

This information must be transferred reliably and in order

Order is easy to take care off. Just add a sequence number to your packets to tell them apart (yes, that's another overhead, but it's small).

You simply cannot have two different sets of 20MB be equivalent, because if you do, you lose information (pidgeon-hole principle). So given 19 packets that are received, there is exactly one 1 MB packet which can be received.

Well, if you re-read my posting, you'll see that yes, any 20 packets would be enough to reconstruct the information (as long as they are different, of course...duplicating a same packet 20 times won't work obviously).

It's been a while since I've calculated hamming distances, so I'm not going to get into the exact number of packets that need to be sent, but I hope that my discussion above showed that the number is greater than simply multiplying by the inverse of the expected reliability.

The number is indeed greater (due to standard deviation), but not substantially so.

If you're interested in the specifics, please read Luigi Rizzo's paper.

You might also want to check out udpcast which provides a working implementation of a FEC algorithm, that works in practice (albeit only on "slice" sizes of up to 128 packets, but that's purely for practical reasons: in theory no such limitation would be necessary).

Well, another solution would be to make sure no asteroids hit the earth :)

There's people working on the problem of tracing "dangerous" objects and calculating the probability of impact.... Have a look at this site to know more (note: it's very technical, but there are links).

This ic already part of FreeBSD - it's called Dummynet and was built just for this purpose -to throttle bandwidth and introduce latency for testing purposes. Here's a good writeup by the guy who wrote it/maintains it.

It seems that rail transportation in north america is going to remain unaffordable for another couple of years with such rates. In Europe one can travel between Brussels, London, Paris, München, Torino, for less than the cost of a flight ticket, and there are special prices for young people. Night trains are also quite popular here (far less comfortable than your bedroom, but far more than a bus).

When I have to travel from my home in Paris (France) to my parents in Bordeaux, it is as fast, cheaper and more convenient to board on a train than to take a flight.

Distance between both towns: about 360 miles (580km).

Train cost for a < 25 years old: less than $26. Full fare rate $47.
Airline cost: cannot be less than $40 (full fare rate beginning at $100).

Train: tube (30 min), wait (10 min), train (3 hours), walk (15 min). Total 3h55. Quite reliable (strikes excepted), not too dependant on weather, and I can use my laptop all the way in the train.

Flight: tube (30 min), wait (20 min), bus (30 min), wait (30 min), flight (1:15), car (25 min). Total 3h30, but my parents have to come to the airport. Quite dependant on weather, and still dependant on strikes. Can't work in the tube, neither in the bus, I can just download my mails while waiting in the airport and read them later onboard (allowed time: about 40min).

As a result, there is no more room on december 23rd trains, but I could buy a student fare ticket (very limited supply) for a flight the same day.

The article does not mention it, but the current world speed record (on "conventional" railways) of more than 320 mph (515km/h) was achieved on this line in the early 90's during test runs, with tuned hardware.

For those interested in high speed train technologies :
http://mercurio.iet.unipi.it/tgv/ tgv index.html

Taking into account new precovery data of the object taken by the Catalina Sky Survey on 17 May 1999 (see http://cfa-www.harvard.edu/mpec/ K00 /K00V15.html), the NEODys team has calculated that the 2030 impact scenario is no longer real (see http://ne wto n.dm.unipi.it/cgi-bin/neodys/neoibo?objects:2000SG 344;main .)

As a result of the new data, there has been a dramatic improvement in the orbital uncertainty. In fact, the nominal miss distance for this object is now given as 0.0346 AU on 22 September 2000 (22.89 UT22.19). What this means is that the object will come no closer to the Earth in 2030 than 3 million miles! In other words, the claim that this object may hit the Earth in 2030 has now been completely ruled out - less than 34 hours after the IAU and NASA decided to announce a "significant impact risk" to the world.

It was unwise of the IAU and NASA to rely on the 1999 one-night stand data by the LINEAR team. The IAU/NASA impact announcement was premature and alarmist.

(Thanks to B. J. Peiser for the above.)

Yawn... Old hat. Can't you slashdotters have a look at history? Otherwise, you'll be condemned at repeating it... badly.

First, a brief word about ekranoplanes (a.k.a. Wing-In-Ground effect). Here is an actual picture of such a beast in flight (Gerry Anderson fans will be delighted by this one). They have been around for almost 40 years, having been devellopped in the defunct Soviet Union . You may look at this page for historic information, as well as pictures of enormous ekranoplanes as well as the 400 ton Lun ICBM launcher . For those who worry about greenhouse gas emissions, there is also a pedal-powered WIG !!! Oh, yes, those craft are already covered by a Canadian regulation, proof that they've been around long enough to rouse the attention of regulators...

Now, about trains. Nothing really new, there either.

In the 1960's, french engineer Jean Bertin (1917-1975) pursued the développement of his ill-fated Aérotrain , which, 30 years before the recently-canned german Transrapid maglev, almost reached the realization stage (both in a commuter rail line betwen Paris and the western sububurb of Cergy, and a line between Lyon and Grenoble for the 1968 winter Olympic games). Bertin's Aérotrains ran on a single inverted T concrete rail, and used a cushion of air for sustentation. An early prototype, the Aérotrain expérimental 02 (which looks like it was inspired by this), reached the speed of 400 km/h in 1966 and 422 km/h in 1969 (not an impressive achievement, since at that time, the rail speed record was achieved in 1955, when an ordinary locomotive pulling four totally normal cars reached the speed of 331 km/h on a perfectly standard railroad line). More pictures are available here.

Despite that, Jean Bertin built more prototypes, and a 20 km long rail line (which still runs accross the countryside, completely abandoned) on which a much bigger "train", which ran not much faster than today's TGVs do (note that the record certificate is issued by the Fédération Aéronautique Internationale , and not the Union Internationale des Chemins de Fer ...).

Bertin's Aérotrain technology almost got selected in place of the current TGV, but at the last minute, State support was withdrawn from the Société Bertin. The Aérotrain (and any other newfangled guided transportation system such as maglevs and monorails - we're in the real world, here, not in Disneyland) suffered most from gross incompatibility with existing rail lines (necessary to enter the core of cities) and an extremely heavy implementation of switches, which precludes their widespread use and thus reduces the flexibility of their rail networks.

Jean Bertin never recovered from the shock of losing State support; he died a few months later, despite having built a prosperous engineering company which still thrives in high-technologies.

Throughout the Aérotrain's history, the French National Railroads (SNCF)'s attitude was extremely interesting. Despite all the media hoopla that surrounded the Aérotrain and the political interest, it did not say anything at all. Not a single word either for or against the Aérotrain was uttered in official french railroad circles. But during that time, the SNCF worked hard at perfecting what is seen today as the epitome of high-speed travel technology, the TGV.

So, it is quite safe to say that this oldfangled flying "train" will certainly not fly very far, because the theorical speed limit of ground travel, the speed of sound, is within reach of conventionnal steel-wheel-on-steel-rail technology, which without much pain, ran at 515,3 km/h on May 18th 1990 (gee! Almost 10 years ago!!!).

(What is the speed of sound at 20C at sea level anyway???)

--

Yawn... Old hat. Can't you slashdotters have a look at history? Otherwise, you'll be condemned at repeating it... badly.

First, a brief word about ekranoplanes (a.k.a. Wing-In-Ground effect). Here is an actual picture of such a beast in flight (Gerry Anderson fans will be delighted by this one). They have been around for almost 40 years, having been devellopped in the defunct Soviet Union . You may look at this page for historic information, as well as pictures of enormous ekranoplanes as well as the 400 ton Lun ICBM launcher . For those who worry about greenhouse gas emissions, there is also a pedal-powered WIG !!! Oh, yes, those craft are already covered by a Canadian regulation, proof that they've been around long enough to rouse the attention of regulators...

Now, about trains. Nothing really new, there either.

In the 1960's, french engineer Jean Bertin (1917-1975) pursued the développement of his ill-fated Aérotrain , which, 30 years before the recently-canned german Transrapid maglev, almost reached the realization stage (both in a commuter rail line betwen Paris and the western sububurb of Cergy, and a line between Lyon and Grenoble for the 1968 winter Olympic games). Bertin's Aérotrains ran on a single inverted T concrete rail, and used a cushion of air for sustentation. An early prototype, the Aérotrain expérimental 02 (which looks like it was inspired by this), reached the speed of 400 km/h in 1966 and 422 km/h in 1969 (not an impressive achievement, since at that time, the rail speed record was achieved in 1955, when an ordinary locomotive pulling four totally normal cars reached the speed of 331 km/h on a perfectly standard railroad line). More pictures are available here.

Despite that, Jean Bertin built more prototypes, and a 20 km long rail line (which still runs accross the countryside, completely abandoned) on which a much bigger "train", which ran not much faster than today's TGVs do (note that the record certificate is issued by the Fédération Aéronautique Internationale , and not the Union Internationale des Chemins de Fer ...).

Bertin's Aérotrain technology almost got selected in place of the current TGV, but at the last minute, State support was withdrawn from the Société Bertin. The Aérotrain (and any other newfangled guided transportation system such as maglevs and monorails - we're in the real world, here, not in Disneyland) suffered most from gross incompatibility with existing rail lines (necessary to enter the core of cities) and an extremely heavy implementation of switches, which precludes their widespread use and thus reduces the flexibility of their rail networks.

Jean Bertin never recovered from the shock of losing State support; he died a few months later, despite having built a prosperous engineering company which still thrives in high-technologies.

Throughout the Aérotrain's history, the French National Railroads (SNCF)'s attitude was extremely interesting. Despite all the media hoopla that surrounded the Aérotrain and the political interest, it did not say anything at all. Not a single word either for or against the Aérotrain was uttered in official french railroad circles. But during that time, the SNCF worked hard at perfecting what is seen today as the epitome of high-speed travel technology, the TGV.

So, it is quite safe to say that this oldfangled flying "train" will certainly not fly very far, because the theorical speed limit of ground travel, the speed of sound, is within reach of conventionnal steel-wheel-on-steel-rail technology, which without much pain, ran at 515,3 km/h on May 18th 1990 (gee! Almost 10 years ago!!!).

(What is the speed of sound at 20C at sea level anyway???)

--

Yawn... Old hat. Can't you slashdotters have a look at history? Otherwise, you'll be condemned at repeating it... badly.

First, a brief word about ekranoplanes (a.k.a. Wing-In-Ground effect). Here is an actual picture of such a beast in flight (Gerry Anderson fans will be delighted by this one). They have been around for almost 40 years, having been devellopped in the defunct Soviet Union . You may look at this page for historic information, as well as pictures of enormous ekranoplanes as well as the 400 ton Lun ICBM launcher . For those who worry about greenhouse gas emissions, there is also a pedal-powered WIG !!! Oh, yes, those craft are already covered by a Canadian regulation, proof that they've been around long enough to rouse the attention of regulators...

Now, about trains. Nothing really new, there either.

In the 1960's, french engineer Jean Bertin (1917-1975) pursued the développement of his ill-fated Aérotrain , which, 30 years before the recently-canned german Transrapid maglev, almost reached the realization stage (both in a commuter rail line betwen Paris and the western sububurb of Cergy, and a line between Lyon and Grenoble for the 1968 winter Olympic games). Bertin's Aérotrains ran on a single inverted T concrete rail, and used a cushion of air for sustentation. An early prototype, the Aérotrain expérimental 02 (which looks like it was inspired by this), reached the speed of 400 km/h in 1966 and 422 km/h in 1969 (not an impressive achievement, since at that time, the rail speed record was achieved in 1955, when an ordinary locomotive pulling four totally normal cars reached the speed of 331 km/h on a perfectly standard railroad line). More pictures are available here.

Despite that, Jean Bertin built more prototypes, and a 20 km long rail line (which still runs accross the countryside, completely abandoned) on which a much bigger "train", which ran not much faster than today's TGVs do (note that the record certificate is issued by the Fédération Aéronautique Internationale , and not the Union Internationale des Chemins de Fer ...).

Bertin's Aérotrain technology almost got selected in place of the current TGV, but at the last minute, State support was withdrawn from the Société Bertin. The Aérotrain (and any other newfangled guided transportation system such as maglevs and monorails - we're in the real world, here, not in Disneyland) suffered most from gross incompatibility with existing rail lines (necessary to enter the core of cities) and an extremely heavy implementation of switches, which precludes their widespread use and thus reduces the flexibility of their rail networks.

Jean Bertin never recovered from the shock of losing State support; he died a few months later, despite having built a prosperous engineering company which still thrives in high-technologies.

Throughout the Aérotrain's history, the French National Railroads (SNCF)'s attitude was extremely interesting. Despite all the media hoopla that surrounded the Aérotrain and the political interest, it did not say anything at all. Not a single word either for or against the Aérotrain was uttered in official french railroad circles. But during that time, the SNCF worked hard at perfecting what is seen today as the epitome of high-speed travel technology, the TGV.

So, it is quite safe to say that this oldfangled flying "train" will certainly not fly very far, because the theorical speed limit of ground travel, the speed of sound, is within reach of conventionnal steel-wheel-on-steel-rail technology, which without much pain, ran at 515,3 km/h on May 18th 1990 (gee! Almost 10 years ago!!!).

(What is the speed of sound at 20C at sea level anyway???)

--

Yawn... Old hat. Can't you slashdotters have a look at history? Otherwise, you'll be condemned at repeating it... badly.

First, a brief word about ekranoplanes (a.k.a. Wing-In-Ground effect). Here is an actual picture of such a beast in flight (Gerry Anderson fans will be delighted by this one). They have been around for almost 40 years, having been devellopped in the defunct Soviet Union . You may look at this page for historic information, as well as pictures of enormous ekranoplanes as well as the 400 ton Lun ICBM launcher . For those who worry about greenhouse gas emissions, there is also a pedal-powered WIG !!! Oh, yes, those craft are already covered by a Canadian regulation, proof that they've been around long enough to rouse the attention of regulators...

Now, about trains. Nothing really new, there either.

In the 1960's, french engineer Jean Bertin (1917-1975) pursued the développement of his ill-fated Aérotrain , which, 30 years before the recently-canned german Transrapid maglev, almost reached the realization stage (both in a commuter rail line betwen Paris and the western sububurb of Cergy, and a line between Lyon and Grenoble for the 1968 winter Olympic games). Bertin's Aérotrains ran on a single inverted T concrete rail, and used a cushion of air for sustentation. An early prototype, the Aérotrain expérimental 02 (which looks like it was inspired by this), reached the speed of 400 km/h in 1966 and 422 km/h in 1969 (not an impressive achievement, since at that time, the rail speed record was achieved in 1955, when an ordinary locomotive pulling four totally normal cars reached the speed of 331 km/h on a perfectly standard railroad line). More pictures are available here.

Despite that, Jean Bertin built more prototypes, and a 20 km long rail line (which still runs accross the countryside, completely abandoned) on which a much bigger "train", which ran not much faster than today's TGVs do (note that the record certificate is issued by the Fédération Aéronautique Internationale , and not the Union Internationale des Chemins de Fer ...).

Bertin's Aérotrain technology almost got selected in place of the current TGV, but at the last minute, State support was withdrawn from the Société Bertin. The Aérotrain (and any other newfangled guided transportation system such as maglevs and monorails - we're in the real world, here, not in Disneyland) suffered most from gross incompatibility with existing rail lines (necessary to enter the core of cities) and an extremely heavy implementation of switches, which precludes their widespread use and thus reduces the flexibility of their rail networks.

Jean Bertin never recovered from the shock of losing State support; he died a few months later, despite having built a prosperous engineering company which still thrives in high-technologies.

Throughout the Aérotrain's history, the French National Railroads (SNCF)'s attitude was extremely interesting. Despite all the media hoopla that surrounded the Aérotrain and the political interest, it did not say anything at all. Not a single word either for or against the Aérotrain was uttered in official french railroad circles. But during that time, the SNCF worked hard at perfecting what is seen today as the epitome of high-speed travel technology, the TGV.

So, it is quite safe to say that this oldfangled flying "train" will certainly not fly very far, because the theorical speed limit of ground travel, the speed of sound, is within reach of conventionnal steel-wheel-on-steel-rail technology, which without much pain, ran at 515,3 km/h on May 18th 1990 (gee! Almost 10 years ago!!!).

(What is the speed of sound at 20C at sea level anyway???)

--

OK, who's going to port this to Linux!?

I'll admit, I had no idea (still don't) know how my cable company (roadrunner) limits thier user bandwidth (anyone know?). But this dummynet thing is just too cool.

Thanks for the info Brian!

You know, there's always the possibility of using Luigi Rizzo's excellent dummynet. Yes, it's for FreeBSD, which would mean changing the Linux firewall box to a FreeBSD firewall box.

Here's some information from the dummynet home page. I hope this helps!

dummynet is a flexible tool for bandwidth management and for testing networking protocols. It is implemented in FreeBSD but is easily portable to other protocol stacks. There is also a one-floppy version of FreeBSD which includes dummynet and a lot of other goodies, see below. dummynet works by intercepting packets in their way through the protocol stack, and passing them through one or more pipes which simulate the effects of bandwidth limitations, propagation delays, bounded-size queues, packet losses, etc.

Each pipe can be configured separately, and packets are forwarded to the appropriate pipe using the ipfw packet filter. Thus you can apply different limitations/delays to different traffic according to the ipfw rules (e.g. selecting on protocols, addresses and ports ranges, interfaces, etc.).

--

[RMS] wrote the original bc manual