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How do Maglev trains work? - Ning Zhao - Video học tiếng Anh
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How do Maglev trains work? - Ning Zhao
How do Maglev trains work? - Ning Zhao
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[music]
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[music]
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>> To coincide with the 1964 Tokyo
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Olympics, [music] Japan launched the
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world's first high-speed train, the
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Shinkansen, [music]
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capable of running at 210 km/h.
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This groundbreaking bullet train
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inspired countries [music] around the
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world to invest in high-speed rail.
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Today, these trains regularly [music]
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travel at over 300 km/h,
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on par with the takeoff speed of a
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commercial [music] airplane.
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But, could these trains go even faster,
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whisking passengers [music] to their
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destinations quicker than the smoothest
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flight?
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To answer this, [music] it helps to
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understand how these trains reach their
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already impressive speeds. There are
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[music] three main factors that separate
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bullet trains from traditional low-speed
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trains:
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engines, aerodynamics, and
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infrastructure. [music]
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Most traditional trains are powered
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[music] by combustion engines,
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which combust fuel, typically diesel, to
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turn an electric generator. [music]
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This electricity is then used to power
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motors that turn the train's wheels.
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High-speed trains, [music]
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on the other hand, use electric engines
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to power their motors. This process is
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more energy efficient [music] than
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combustion, and allows train operators
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to reach top speeds more quickly.
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Next up is aerodynamics.
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While low- and [music] high-speed trains
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use the same steel wheels to minimize
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friction with the track, bullet trains
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are also [music] designed with
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aerodynamic bodies that slice through
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air with minimal [music] resistance.
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Engineers could use these slicker
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designs on traditional train cars.
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[music]
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But while upgrading to electric engines
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would make low-speed trains more
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efficient, they wouldn't [music] get
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much benefit from these aerodynamic
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designs because of the third factor,
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infrastructure.
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Traditional train tracks were built to
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meet people [music] where they lived,
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ensuring stations were accessible to any
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potential passengers.
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But to prevent derailments in these
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highly populated areas, trains need
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[music] to frequently decelerate to
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safely hit turns and crossroads.
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High-speed rails, on the other hand,
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were built to prioritize speed. They run
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on long, straight [music] lines that
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avoid road crossings, sharp curves, and
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high-traffic [music] areas.
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These three differences allow high-speed
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trains [music]
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to reach top speeds over double their
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traditional counterparts. And since
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their infrastructure allows them to
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travel longer distances [music] between
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stops, they spend more time cruising
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near top speed, often traveling [music]
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up to three times the average speed of
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traditional trains.
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But new technology is emerging [music]
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to make even faster trains.
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To eliminate friction between rails and
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wheels, engineers have developed new
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magnetic levitation, or maglev, trains.
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There are two major approaches here.
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In electromagnetic suspension,
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magnetized arms wrap under [music] the
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track and pull the train up. Meanwhile,
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in electrodynamic suspension, coils
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embedded in the track [music] create a
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pattern of alternating magnetic fields
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that interact with magnets on the train
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[music]
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to float the vehicle a few centimeters
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in the air.
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To change speed, [music] train operators
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alternate the direction of the train's
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magnetic field, attracting the front of
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the train to the next coil to speed up,
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or reversing the field's [music] phase
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to brake.
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Given enough runway, these trains can
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reach speeds from 430 to a theoretical
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600 km/h,
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allowing them to make the over 4,400
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km trip from New York City to Los
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Angeles in as little as 7 hours. [music]
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So, why haven't we built Maglev trains
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or even high-speed trains everywhere?
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[music]
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First, these trains require lots of
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energy, most of which is needed [music]
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to overcome air resistance. In fact, at
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300 km/h, [music]
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this task accounts for over 80% of
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train's energy consumption.
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Engineers [music] are researching ways
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to reduce air resistance, such as
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putting Maglevs in near vacuum
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environments.
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But, building a vacuum-sealed tunnel
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across an entire country would be an
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infrastructure [music]
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project of science-fictional
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proportions.
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Besides, it's hard enough to build
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regular high-speed rails. To go fast,
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[music]
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trains need long, straight tracks with
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wide curves, which are very difficult to
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build in mountains, cities, or [music]
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densely populated areas.
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Building such routes is costly,
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politically sensitive, and often [music]
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physically impossible.
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Despite these hurdles, Japan and China
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[music] are expanding their existing
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high-speed and Maglev rails,
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>> [music]
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>> and several projects currently in
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development might finally bring
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high-speed rail to the US.
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But, we'll need to carefully consider
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our trains' top speeds alongside cost,
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energy use, and safety to keep the
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future of train travel on the right
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track.
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>> [music]
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