Thursday, September 10, 2009

JR–Maglev

JR-Maglev is a magnetic levitation train system developed by the Central Japan Railway Company and Railway Technical Research Institute (association of Japan Railways Group). JR-Maglev MLX01 (X means experimental) is one of the latest designs of a series of Maglev trains in development in Japan since the 1970s. It is composed of a maximum five cars to run on the Yamanashi Maglev Test Line. On December 2, 2003, a three-car train set attained a maximum speed of 581 km/h (361 mph) (world speed record for railed vehicles) in a manned vehicle run.

Fundamental technology elements
The term "maglev" refers not only to the vehicles, but to the railway system as well, specifically designed for magnetic levitation and propulsion. All operational implementations of maglev technology have had minimal overlap with wheeled train technology and have not been compatible with conventional rail tracks. Because they cannot share existing infrastructure, these maglev systems must be designed as complete transportation systems. The Applied Levitation SPM Maglev system is inter-operable with steel rail tracks and would permit maglev vehicles and conventional trains to operate at the same time on the same right of way.
There are three primary types of maglev technology:
1) For electromagnetic suspension (EMS), electromagnets in the train repel it away from a magnetically conductive (usually steel) track.
2) electrodynamic suspension (EDS) uses electromagnets on both track and train to push the train away from the rail.
3) stabilized permanent magnet suspension (SPM) uses opposing arrays of permanent magnets to levitate the train above the rail.

Another experimental technology, which was designed, proven mathematically, peer reviewed, and patented, but is yet to be built, is the magnetodynamic suspension (MDS), which uses the attractive magnetic force of a permanent magnet array near a steel track to lift the train and hold it in place.

Commercial operation
The first commercial Maglev "people-mover" was officially opened in 1984 in Birmingham, England. It operated on an elevated 600-metre (2,000 ft) section of monorail track between Birmingham International Airport and Birmingham International railway station. It ran at 42 km/h (26 mph) until the system was eventually closed in 1995 due to reliability and design problems.
The best-known high-speed maglev currently operating commercially is the IOS (initial operating segment) demonstration line of the German-built Transrapid train in Shanghai, China that transports people 30 km (18.6 miles) to the airport in just 7 minutes 20 seconds, achieving a top speed of 431 km/h (268 mph), averaging 250 km/h (150 mph).
Other commercially operating lines exist in Japan, such as the Linimo line. Maglev projects worldwide are being studied for feasibility. In Japan at the Yamanashi test track, current maglev train technology is mature, but costs and problems remain a barrier to development. Alternative technologies are being developed to address those issues.

Levitation
The JR-Maglev levitation train uses an Electro-dynamic Suspension (EDS) system. Moving magnetic fields create a reactive force in a conductor because of the magnetic field induction effect. This force holds up the train. The maglev-trains have superconducting magnetic coils, and the guide ways contain levitation coils.
When the trains run at high speed, levitation coils on the guide way produce reactive forces in response to the approach of the superconducting magnetic coils onboard the trains.
EDS has the advantage of larger gaps than EMS, but EDS needs support wheels which are employed in low speed running, because EDS can't produce a large levitation force at low(er) speeds (150km/h or less in JR-Maglev). However, once the train reaches a certain speed, the wheels will actually retract so that the train is floating.

Guide
Levitation coils which are located on the guide way generate guiding and stabilizing forces also.

Driving
JR-Maglev is driven by a Linear Synchronous Motor (LSM) System. This system is needed to supply power to the coils at the guide way.

Evacuated tubes
Some systems (notably the swissmetro system) propose the use of vactrains — evacuated (airless) tubes used in tandem with maglev technology to minimize air drag. This has the potential to increase speed and efficiency greatly, as most of the energy for conventional Maglev trains is lost in air drag.
One potential risk for passengers of trains operating in evacuated tubes is that they could be exposed to the risk of cabin depressurization and asphyxiation unless tunnel safety monitoring systems can repressurize the tube in the event of a train malfunction or accident.

Yamanashi Test Track
Yamanashi Experiment Lines are facilities that currently have a practical use. It includes about 18.4 km of track (including 16.0 km of tunnels).

JR-Maglev, Japan
Japan has a demonstration line in Yamanashi prefecture where test trains JR-Maglev MLX01 have reached 581 kilometres per hour (361 mph), slightly faster than any wheeled trains (the current TGV speed record is 574.8 kilometres per hour (357.2 mph)). A documentary video about the Japanese maglev can be viewed here.
These trains use superconducting magnets which allow for a larger gap, and repulsive-type electrodynamic suspension (EDS). In comparison Transrapid uses conventional electromagnets and attractive-type electromagnetic suspension (EMS). These "Superconducting Maglev Shinkansen", developed by the Central Japan Railway Company (JR Central) and Kawasaki Heavy Industries, are currently the fastest trains in the world, achieving a record speed of 581 kilometres per hour (361 mph) on December 2, 2003. Yamanashi Prefecture residents (and government officials) can sign up to ride this for free, and some 100,000 have done so already.
 
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