Electrical
engineering is a field of engineering that
generally deals with the study and application of electricity, electronics,
and electromagnetism. This field first became an
identifiable occupation in the latter half of the 19th century after
commercialization of the electric telegraph,
the telephone,
and electric power distribution and use. It
now covers a wide range of subfields including electronics, digital
computers, power
engineering, telecommunications, control
systems, RF engineering, and signal
processing.
Electrical engineering may
include electronic engineering. Where a
distinction is made, usually outside of the United States, electrical
engineering is considered to deal with the problems associated with systems
such as electric power transmission and electrical machines, whereas electronic
engineering deals with the study of electronic systems including computers, communication systems, integrated circuits, and radar.
From a different point-of-view,
electrical engineers are usually concerned with using electricity to
transmit electric power, while electronic engineers are
concerned with using electricity to process information. The sub disciplines
can overlap, for example, in the growth of power
electronics, and the study of behavior of large electrical grids
under the control of digital computers and electronics.
Electricity has been a subject of
scientific interest since at least the early 17th century. The first electrical
engineer was probably William
Gilbert who designed the versorium. a device that detected the presence of
statically charged objects. He was also the first to draw a clear distinction
between magnetism and static electricity and is credited with establishing the
term electricity. In 1775 Alessandro Volta's scientific
experimentations devised the electrophorus, a device that produced a
static electric charge, and by 1800 Volta developed the voltaic pile, a forerunner of the electric
battery.
19th century
However, it was not until the 19th
century that research into the subject started to intensify. Notable
developments in this century include the work of Georg Ohm, who in 1827 quantified the
relationship between the electric current and potential
difference in a conductor, Michael Faraday, the discoverer of electromagnetic
induction in 1831, and James Clerk
Maxwell, who in 1873 published a unified theory of
electricity and magnetism in
his treatise Electricity and Magnetism.
Beginning in the 1830s, efforts were
made to apply electricity to practical use in the telegraph. By the end of the 19th century
the world had been forever changed by the rapid communication made possible by
engineering development of land-lines, submarine cables, and, from about 1890, wireless
telegraphy.
Practical applications and advances in
such fields created an increasing need for standardized units of measure. They
led to the international standardization of the units volt, ampere, coulomb, ohm, farad, and henry. This was achieved at an
international conference in Chicago 1893. The publication of these
standards formed the basis of future advances in standardisation in various
industries, and in many countries the definitions were immediately recognised
in relevant legislation.
During
these years, the study of electricity was largely considered to be a subfield
of physics. It was not until
about 1885 that universities and institutes of technology such as Massachusetts Institute of Technology (MIT)
and Cornell University started to offer bachelor's degrees in electrical engineering. TheDarmstadt University of Technology founded
the first department of electrical engineering in the world in 1882. In that
same year, under Professor Charles Cross at MIT began offering the first option
of electrical engineering within its physics department. In
1883, Darmstadt University of Technology and
Cornell University introduced the world's first bachelor's degree courses of
study in electrical engineering, and in 1885 the University College London founded the first chair of electrical engineering
in Great
Britain.The University of Missouri established the first department
of electrical engineering in the United States in 1886.Several other
schools soon followed suit, including Cornell and the Georgia School of Technology in Atlanta, Georgia.
Nikola Tesla developedtransformers and induction motorsfor use in AC
During these decades use of electrical
engineering increased dramatically. In 1882, Thomas Edison switched on the world's
first large-scale electric power network that provided 110 volts — direct current (DC) — to 59 customers
on Manhattan Islandin New York City. In 1884, Sir Charles
Parsons invented the steam turbine. Turbines now provide the
mechanical power for about 80 percent of the electric power in the world using
a variety of heat sources.
The late 1880s saw a rivalry in
systems for electric power distribution
with the introduction of alternating
current (AC) systems, setting off what has been called
the War of Currents.The method of AC won over
DC for generation and power distribution because of its superior technology,
especially the use of transformers to
increase and decrease voltages (not possible with DC). The use of high-voltage
AC vastly extended the range of electric power distribution, and the use of
transfomers improved both the efficiency and the safety of electric power
distribution.
More modern developments
During the development
of radio, many scientists and inventors contributed to radio
technology and electronics. In his classic physics experiments
of 1888,Heinrich Hertz transmitted radio waves with a spark-gap
transmitter, and detected them by using simple electrical devices.
The mathematical work of James Clerk
Maxwell during the 1850s had shown the possibility of radio
waves but Hertz was the first to demonstrate their existence. In 1895, Nikola
Tesla was able to detect radio signals from his transmitter in his laboratory
in New York City about
50 miles away in West Point,
New York (about 80 kilometers).
In 1897, Karl
Ferdinand Braun introduced the cathode ray tube as part of an oscilloscope, a crucial enabling
technology for electronic
television. John Fleminginvented
the first radio tube, the diode, in 1904. Two years
later, Robert von
Lieben and Lee De Forest independently developed
the amplifier tube, called the triode.n 1895, Guglielmo Marconifurthered the art of
hertzian wireless methods. Early on, he sent wireless signals over a distance
of one and a half miles. In December 1901, he sent wireless waves that were not
affected by the curvature of the Earth. Marconi later transmitted the wireless
signals across the Atlantic between Poldhu, Cornwall, and St. John's,
Newfoundland, a distance of 2,100 miles (3,400 km). In 1920 Albert Hull developed the magnetron which would eventually lead
to the development of the microwave oven in 1946 by Percy Spencer.In 1934 the British
military began to make strides toward radar (which also uses the magnetron)
under the direction of Dr Wimperis, culminating in the operation of the first
radar station at Bawdsey in
August 1936.
In 1941 Konrad Zuse presented the Z3, the world's first fully functional and
programmable computer using electromechanical parts. In 1943 Tommy Flowers designed and built
the Colossus,
the world's first fully functional, electronic, digital and programmable
computer.[ In 1946 the ENIAC (Electronic Numerical Integrator and
Computer) of John Presper
Eckert and John Mauchly followed, beginning the
computing era. The arithmetic performance of these machines allowed engineers
to develop completely new technologies and achieve new objectives, including
the Apollo program which
culminated in landing astronauts
on the Moon.
A complete breakthrough in electronics
- solid-state transistors
The invention of the transistor in late 1947 by William B.
Shockley, John Bardeen,
and Walter Brattain of
the Bell
Telephone Laboratories opened the door for more compact devices
and led to the development of the integrated
circuit in 1958 by Jack Kilby and independently in 1959
by Robert Noyce. Starting in 1968, Ted Hoff and a team at the Intel Corporation invented the first
commercial microprocessor,
which foreshadowed the personal computer. The Intel 4004 was a four-bit processor
released in 1971, but in 1973 the Intel 8080, an eight-bit processor, made
the first personal computer, the Altair 8800, possible.
Education
Main article: Education and training of electrical and electronics
engineers
Electrical engineers typically possess
an academic degree with
a major in electrical engineering, electronics
engineering, or electrical and electronic engineering.
The same fundamental principles are taught in all programs, though emphasis may
vary according to title. The length of study for such a degree is usually four
or five years and the completed degree may be designated as a Bachelor of
Engineering, Bachelor of
Science, Bachelor of
Technology, or Bachelor of
Applied Science depending on the university. The bachelor's
degree generally includes units covering physics, mathematics, computer science, project
management, and a variety of topics in electrical engineering. Initially such
topics cover most, if not all, of the subdisciplines of electrical engineering.
At some schools, the students can then choose to emphasize one or more
subdisciplines towards the end of their courses of study. At many schools,
electronic engineering is included as part of an electrical award, sometimes
explicitly, such as a Bachelor of Engineering (Electrical and Electronic), but
in others electrical and electronic engineering are both considered to be
sufficiently broad and complex that separate degrees are offered.
Some electrical engineers choose to
study for a postgraduate degree such as a Master of
Engineering/Master of
Science (M.Eng./M.Sc.), a Master of Engineering
Management, a Doctor of
Philosophy (Ph.D.) in Engineering, an Engineering
Doctorate (Eng.D.), or an Engineer's
degree. The master's and engineer's degrees may consist of
either research, coursework or a mixture of the two.
The Doctor of Philosophy and Engineering Doctorate degrees consist of a
significant research component and are often viewed as the entry point to academia. In the United Kingdom and some
other European countries, Master of Engineering is often considered to be an
undergraduate degree of slightly longer duration than the Bachelor of
Engineering rather than postgraduate.
Practicing engineers
In most countries, a Bachelor's degree
in engineering represents the first step towards professional
certification and the degree program itself is certified by
a professional
body. After completing a certified degree program the engineer must
satisfy a range of requirements (including work experience requirements) before
being certified. Once certified the engineer is designated the title of Professional
Engineer (in the United States, Canada and South Africa
), Chartered
Engineer or Incorporated
Engineer (in India, Pakistan, the United Kingdom, Ireland
and Zimbabwe), Chartered Professional Engineer
(in Australia and New Zealand) or European Engineer (in much of
the European Union).
The advantages of certification vary
depending upon location. For example, in the United States and Canada
"only a licensed engineer may seal engineering work for public and private
clients".This requirement is enforced by
state and provincial legislation such as Quebec's Engineers Act. In other countries, no
such legislation exists. Practically all certifying bodies maintain a code of ethics that they expect all
members to abide by or risk expulsion. In this way these
organizations play an important role in maintaining ethical standards for the
profession. Even in jurisdictions where certification has little or no legal
bearing on work, engineers are subject to contract law. In cases where an engineer's
work fails he or she may be subject to the tort of negligence and, in extreme
cases, the charge of criminal
negligence. An engineer's work must also comply with numerous other
rules and regulations such as building codes and legislation
pertaining to environmental
law.
Professional bodies of note for
electrical engineers include the Institute of Electrical and Electronics Engineers (IEEE)
and the Institution of Engineering and Technology (IET). The IEEE
claims to produce 30% of the world's literature in electrical engineering, has
over 360,000 members worldwide and holds over 3,000 conferences annually. The IET publishes 21
journals, has a worldwide membership of over 150,000, and claims to be the
largest professional engineering society in Europe. Obsolescence of technical
skills is a serious concern for electrical engineers. Membership and
participation in technical societies, regular reviews of periodicals in the
field and a habit of continued learning are therefore essential to maintaining
proficiency. MIET(Member of the Institution of Engineering and Technology) is
recognised in Europe as Electrical and computer (technology) engineer.
In Australia, Canada and the United
States electrical engineers make up around 0.25% of the labor force . Outside of Europe and North
America, engineering graduates per-capita, and hence probably electrical
engineering graduates also, are most numerous in Taiwan, Japan, and South
Korea.
Tools and work
From the Global
Positioning System to electric
power generation, electrical engineers have contributed to the
development of a wide range of technologies. They design, develop, test and
supervise the deployment of electrical systems and electronic devices. For
example, they may work on the design of telecommunication systems, the operation
of electric power
stations, the lighting and wiring of buildings, the design of household appliances or the
electrical control of
industrial machinery.
Satellite
communications is one of many projects an electrical engineer
might work on.
Fundamental to the discipline are the
sciences of physics and mathematics as these help to obtain
both a qualitative and quantitative description of how such
systems will work. Today most engineering work involves the use
of computers and it is commonplace to
use computer-aided
design programs when designing electrical systems.
Nevertheless, the ability to sketch ideas is still invaluable for quickly
communicating with others.
Although most electrical engineers
will understand basic circuit theory (that
is the interactions of elements such as resistors, capacitors, diodes,transistors and inductors in a circuit), the theories
employed by engineers generally depend upon the work they do. For
example, quantum
mechanicsand solid state
physics might be relevant to an engineer working on VLSI (the design of integrated circuits),
but are largely irrelevant to engineers working with macroscopic electrical
systems. Even circuit theory may
not be relevant to a person designing telecommunication systems that use off-the-shelf components.
Perhaps the most important technical skills for electrical engineers are
reflected in university programs, which emphasize strong numerical skills, computer literacy and the ability to
understand the technical
language and concepts that relate to electrical engineering.
For many engineers, technical work
accounts for only a fraction of the work they do. A lot of time may also be
spent on tasks such as discussing proposals with clients, preparing budgets and determining project
schedules. Many senior engineers
manage a team of technicians or
other engineers and for this reason project
management skills are important. Most engineering projects
involve some form of documentation and strong written communication skills
are therefore very important.
The workplaces of electrical engineers are
just as varied as the types of work they do. Electrical engineers may be found
in the pristine lab environment of a fabrication plant, the offices of aconsulting firm or on site at a mine. During their working life, electrical
engineers may find themselves supervising a wide range of individuals
including scientists, electricians, computer
programmers and other engineers.
Subdisciplines
Electrical engineering has many
subdisciplines, the most popular of which are listed below. Although there are
electrical engineers who focus exclusively on one of these subdisciplines, many
deal with a combination of them. Sometimes certain fields, such as electronic
engineering and computer
engineering, are considered separate disciplines in their own right.
1.Power
Main article: Power engineering
Power pole
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.
2. Control
Main article: Control
engineering
Control systems play
a critical role in space flight.
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 theorycan
be used to determine how the system responds to such feedback.
3. Electronics
Main article: Electronic engineering
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 andradar, 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 nameelectronic
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.
4.Microelectronics
Main article: Microelectronics
Microprocessor
Microelectronics engineering deals
with the design and microfabrication 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. Nanoelectronics is
the further scalingof
devices down to nanometer levels.
Modern devices are already in the nanometer regime, with below 100 nm
processing having been standard since about 2002.
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.
5. Signal processing
Main article: Signal processing
A Bayer filter on
a CCD requires
signal processing to get a red, green, and blue value at each pixel.
Signal processing deals with the
analysis and manipulation 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.
Signal Processing is a very
mathematically oriented and intensive area forming the core of digital
signal processing and it is rapidly expanding with new
applications in every field of electrical engineering such as communications,
control, radar, TV/Audio/Video engineering, power electronics and bio-medical
engineering as many already existing analog systems are replaced with their
digital counterparts. Analog signal
processing is still important in the design of many control systems.
DSP processor ICs are found in every
type of modern electronic systems and products including, SDTV | HDTV sets, radios and mobile communication
devices, Hi-Fi audio equipment, Dolby noise reduction algorithms, GSM mobile phones, mp3 multimedia players, camcorders and digital cameras,
automobile control systems, noise cancelling headphones,
digital spectrum
analyzers, intelligent missile guidance, radar, GPS based cruise control systems and all kinds of image processing, video processing, audio
processing and speech processing systems.
6. Telecommunications
Main article: Telecommunications engineering
Satellite dishes are
a crucial component in the analysis of satellite information.
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 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.
7. Instrumentation
Main article: Instrumentation
engineering
Flight
instruments provide pilots the tools to control aircraft
analytically.
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, flight
instruments measure variables such as wind speed and altitude to enable pilots the control
of aircraft analytically. 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.
8. Computers
Main article: Computer
engineering
Supercomputers are
used in fields as diverse as computational
biology and geographic information systems.
Computer engineering deals with the
design of computers and computer systems. This may involve the
design of new hardware,
the design of PDAs,
tablets and supercomputers 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.
Well
enjoy this blog by reading things related to electrical and computer
engineering. Especially for those who are in Ethiopian universities and
companies, This focuses every projects and innovations in accordance of our
country status!!
Mesfin Teshome
Hawassa university Electrical and
computer
engineering department
No comments:
Post a Comment