(难度B/A级/2008年理工类教材新增文章)

But that was 15 years ago, and — fantastic science was done, really
important work. We’ve learned a lot. We were never able to translate
that science into new technologies — into technologies that could
actually impact people. And the reason is, these nanomaterials —
they’re like a double-edged sword. The same thing that makes them so
interesting — their small size — also makes them impossible to work
with. It’s literally like trying to build a statue out of a pile of
dust. And we just don’t have the tools that are small enough to work
with them. But even if we did, it wouldn’t really matter, because we
couldn’t one by one place millions of particles together to build a
technology. So because of that, all of the promise and all of the
excitement has remained just that: promise and excitement. We don’t have
any disease-fighting nanobots, there’s no elevators to space, and the
thing that I’m most interested in, no new types of computing.

If the APU fails before engine start, the engines cannot be started
without an external “start cart” to provide a source of bleed air. If
the APU fails mid-flight, there will be no immediate effect. Even
without the APU, there are two additional ways to restart an aircraft
engine in flight:

B A description of the nanomotor in terms of power and size.

The point is the progress — it’s not gradual. The progress is
relentless. It’s exponential. It compounds on itself year after year, to
the point where if you compare a technology from one generation to the
next, they’re almost unrecognizable. And we owe it to ourselves to keep
this progress going. We want to say the same thing 10, 20, 30 years from
now: look what we’ve done over the last 30 years. Yet we know this
progress may not last forever. In fact, the party’s kind of winding
down. It’s like “last call for alcohol,” right? If you look under the
covers, by many metrics like speed and performance, the progress has
already slowed to a halt. So if we want to keep this party going, we
have to do what we’ve always been able to do, and that is to innovate.

  • It provides cabin air and electric power before the engines are
    started (saving battery power).
  • It provides an emergency source of electric power in the event of
    engine failure.
  • It can start the aircraft engines mid-flight in an emergency.

B A description of the nanomotor in terms of power and size.

At this point, we said, “Let’s just stop. Let’s not go down that same
road. Let’s just figure out what’s missing. What are we not dealing
with? What are we not doing that needs to be done?” It’s like in “The
Godfather,” right? When Fredo betrays his brother Michael, we all know
what needs to be done. Fredo’s got to go.

APUs fitted to ***extended-range twin-engine operations (ETOPS)
***aircraft are a critical safety device, as they supply backup
electricity and compressed air in place of the dead engine or failed
main engine generator. While some APUs may not be startable in flight,
ETOPS-compliant APUs must be flight-startable at altitudes up to the
aircraft service ceiling. Recent applications have specified starting up
to 43,000 ft (13,000 m) from a complete cold-soak condition such as the
Hamilton Sundstrand APS5000 for the Boeing 787 Dreamliner. If the APU or
its electrical generator is not available, the aircraft cannot be
released for ETOPS flight and is forced to take a longer non-ETOPS
route.

  1. Paragraph 4 ____.

  2. Although the amount of energy(能量) produced is small — 20
    microwatts( 百万分之一瓦) — it is quite impressive( 给人印象深刻的) in
    relation to(与…相比 )the tiny scale of the motor. The whole setup is
    less than 200 nanometers( 纳米) on a side, or hundreds of times smaller
    than the width(宽度) of a human hair. If it could be scaled up to the
    size of an automobile engine, it would be 100 million times more
    powerful(强大的) than a Toyota Camry’s 225 horsepower(马力) V6
    engine.

Let’s imagine a sculptor building a statue, just chipping away with his
chisel. Michelangelo had this elegant way of describing it when he said,
“Every block of stone has a statue inside of it, and it’s the task of
the sculptor to discover it.” But what if he worked in the opposite
direction? Not from a solid block of stone, but from a pile of dust,
somehow gluing millions of these particles together to form a statue.

  • a cross-bleed start, where bleed air from a working engine is used
    to start a dead engine, or
  • a windmill start, where the aircraft dives and attains enough speed
    that ram air spins the turbine fast enough to allow a relight.

The Tiniest Electric Motor in the World

Now that last one, that’s a really important one. We just have come to
expect the pace of computing advancements to go on indefinitely. We’ve
built entire economies on this idea. And this pace exists because of our
ability to pack more and more devices onto a computer chip. And as those
devices get smaller, they get faster, they consume less power and they
get cheaper. And it’s this convergence that gives us this incredible
pace.

图片 1

E The working principle of the nanomotor.

And we were doing it — and by we I mean my whole generation of graduate
students. We were trying to make blazing fast computers using
nanomaterials. We were constructing quantum dots that could one day go
in your body and find and fight disease. There were even groups trying
to make an elevator to space using carbon nanotubes. You can look that
up, that’s true. Anyways, we thought it was going to affect all parts of
science and technology, from computing to medicine. And I have to admit,
I drank all of the Kool-Aid. I mean, every last drop.

延伸阅读:
An auxiliary power unit (APU) is a device on a vehicle that provides
energy for functions other than propulsion. They are commonly found on
large aircraft and naval ships as well as some large land vehicles.
Aircraft APUs generally produce 115 V alternating current (AC) at 400 Hz
(rather than 50/60 Hz in mains supply), to run the electrical systems of
the aircraft; others can produce 28 V direct current (DC). APUs can
provide power through single- or three-phase systems.
APU Function

D Previous inventions of nanoscale(纳米级的) products.

(Laughter)

APIC APS3200 APU for Airbus A320 family.
The primary purpose of an aircraft APU is to provide power to start the
main engines. Turbine engines must be accelerated to a high rotational
speed to provide sufficient air compression for self-sustaining
operation. Smaller jet engines are usually started by an electric motor,
while larger engines are usually started by an air turbine motor. Before
the engines are to be turned, the APU is started, generally by a battery
or hydraulic accumulator. Once the APU is running, it provides power
(electric, pneumatic, or hydraulic, depending on the design) to start
the aircraft’s main engines.

D Previous inventions of nanoscale(纳米级的) products.

I know that’s an absurd notion. It’s probably impossible. The only way
you get a statue from a pile of dust is if the statue built itself — if
somehow we could compel millions of these particles to come together to
form the statue.

The APU is normally left off in flight, but may be turned on for certain
long-haul overwater flights as an extra precaution.

A An introduction of a Toyota’s 225 horsepower V6 engine.

(Laughter)

APUs are also used to run accessories while the engines are shut down.
This allows the cabin to be comfortable while the passengers are
boarding before the aircraft’s engines are started. Electrical power is
used to run systems for preflight checks. Some APUs are also connected
to a hydraulic pump, allowing crews to operate hydraulic equipment (such
as flight controls or flaps) prior to engine start. This function can
also be used, on some aircraft, as a backup in flight in case of engine
or hydraulic failure.

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