Power
Power engineering deals with the generation,
transmission and
distribution of
electricity as well as the design of a range of related devices. These
include
transformers,
electric generators,
electric motors, high voltage engineering and
power electronics.
In many regions of the world, governments maintain an
electrical network called a
power grid that connects a variety of generators together with users of
their energy. Users purchase electrical energy from the grid, avoiding the
costly exercise of having to generate their own. Power engineers may work on the
design and maintenance of the power grid as well as the power systems that
connect to it. Such systems are called on-grid power systems and may
supply the grid with additional power, draw power from the grid or do both.
Power engineers may also work on systems that do not connect to the grid, called
off-grid power systems, which in some cases are preferable to on-grid
systems. The future includes Satellite controlled power systems, with feedback
in real time to prevent power surges and prevent blackouts.
Control
Control engineering focuses on the
modeling of a diverse range of
dynamic systems and the design of
controllers that will cause these systems to behave in the desired manner.
To implement such controllers electrical engineers may use
electrical circuits,
digital signal processors,
microcontrollers and
PLCs (Programmable Logic Controllers).
Control engineering has a wide range of applications from the flight and
propulsion systems of
commercial
airliners to the
cruise control present in many modern
automobiles.
It also plays an important role in
industrial automation.
Control engineers often utilize
feedback
when designing
control systems. For example, in an
automobile
with
cruise control the vehicle's
speed is
continuously monitored and fed back to the system which adjusts the
motor's
power output accordingly. Where there is regular feedback,
control theory can be used to determine how the system responds to such
feedback.
Electronics
Electronic engineering involves the design and testing of
electronic circuits that use the properties of
components such as
resistors,
capacitors,
inductors,
diodes and
transistors
to achieve a particular functionality. The
tuned circuit, which allows the user of a
radio to
filter out all but a single station, is just one example of such a circuit.
Another example (of a pneumatic signal conditioner) is shown in the adjacent
photograph.
Prior to the second world war, the subject was commonly known as radio
engineering and basically was restricted to aspects of communications and
radar,
commercial radio
and early
television. Later, in post war years, as consumer devices began to be
developed, the field grew to include modern television, audio systems,
computers
and
microprocessors. In the mid to late 1950s, the term radio engineering
gradually gave way to the name electronic engineering.
Before the invention of the
integrated circuit in 1959, electronic circuits were constructed from
discrete components that could be manipulated by humans. These discrete circuits
consumed much space and
power and were limited in speed, although they are still common in some
applications. By contrast,
integrated circuits packed a large number�often millions�of tiny electrical
components, mainly
transistors,
into a small chip around the size of a
coin. This allowed
for the powerful
computers
and other electronic devices we see today.
Microelectronics
Microelectronics engineering deals with the design of very small electronic
circuit components for use in an
integrated circuit or sometimes for use on their own as a general electronic
component. The most common microelectronic components are
semiconductor
transistors, although all main electronic components (resistors,
capacitors,
inductors) can be created at a microscopic level.
Microelectronic components are created by chemically fabricating wafers of
semiconductors such as silicon (at higher frequencies,
compound semiconductors like gallium arsenide and indium phosphide) to
obtain the desired transport of electronic charge and control of current. The
field of microelectronics involves a significant amount of chemistry and
material science and requires the electronic engineer working in the field to
have a very good working knowledge of the effects of
quantum mechanics.
Signal processing
Signal processing deals with the analysis and manipulations of
signals. Signals can be either
analog, in which case the signal varies continuously according to the
information, or
digital, in which case the signal varies according to a series of discrete
values representing the information. For analog signals, signal processing may
involve the
amplification and
filtering of audio signals for audio equipment or the
modulation
and
demodulation of signals for
telecommunications. For digital signals, signal processing may involve the
compression,
error detection and
error correction of digitally sampled signals.
Telecommunications
Telecommunications engineering focuses on the
transmission of
information across a
channel such as a
coax cable,
optical fiber or
free space.
Transmissions across free space require information to be encoded in a
carrier
wave in order to shift the information to a
carrier frequency suitable for transmission, this is known as
modulation.
Popular analog modulation techniques include
amplitude modulation and
frequency modulation. The choice of modulation affects the cost and
performance of a system and these two factors must be balanced carefully by the
engineer.
Once the transmission characteristics of a system are determined,
telecommunication engineers design the
transmitters and
receivers needed for such systems. These two are sometimes combined to form
a two-way communication device known as a
transceiver. A key consideration in the design of transmitters is their
power consumption as this is closely related to their
signal strength. If the signal strength of a transmitter is insufficient the
signal's information will be corrupted by
noise.
Instrumentation engineering
Instrumentation engineering deals with the design of devices to measure
physical quantities such as
pressure,
flow and
temperature. The design of such instrumentation requires a good
understanding of
physics that often extends beyond
electromagnetic theory. For example,
radar guns
use the
Doppler effect to measure the speed of oncoming vehicles. Similarly,
thermocouples use the
Peltier-Seebeck effect to measure the temperature difference between two
points.
Often instrumentation is not used by itself, but instead as the
sensors of
larger electrical systems. For example, a thermocouple might be used to help
ensure a furnace's temperature remains constant. For this reason,
instrumentation engineering is often viewed as the counterpart of control
engineering.
Computers
Computer engineering deals with the design of
computers
and
computer systems. This may involve the design of new
hardware,
the design of
PDAs or the use of computers to control an
industrial plant. Computer engineers may also work on a system's
software. However, the design of complex software systems is often the
domain of
software engineering, which is usually considered a separate discipline.
Desktop computers represent a tiny fraction of the devices a computer
engineer might work on, as computer-like architectures are now found in a range
of devices including
video game consoles and
DVD players.
Related disciplines
Mechatronics is an engineering discipline which deals with the convergence
of electrical and
mechanical systems. Such combined systems are known as
electromechanical systems and have widespread adoption. Examples include
automated
manufacturing systems,
heating, ventilation
and air-conditioning systems and various subsystems of
aircraft
and
automobiles.
The term mechatronics is typically used to refer to
macroscopic systems but
futurists have predicted the emergence of very small electromechanical
devices. Already such small devices, known as
micro electromechanical systems (MEMS), are used in automobiles to tell
airbags when to
deploy, in
digital projectors to create sharper images and in
inkjet printers to create nozzles for high definition printing. In the
future it is hoped the devices will help build tiny implantable medical devices
and improve
optical communication.
Biomedical engineering is another related discipline, concerned with the
design of
medical equipment. This includes fixed equipment such as
ventilators,
MRI
scanners and
electrocardiograph monitors as well as mobile equipment such as
cochlear implants,
artificial pacemakers and
artificial hearts.
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