Electronic filter
Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both. Electronic filters can be:
- passive or active
- analog or digital
- high-pass, low-pass, bandpass, band-reject (band reject; notch), or all-pass.
- discrete-time (sampled) or continuous-time
- linear or non-linear
- infinite impulse response (IIR type) or finite impulse response (FIR type)
The most common types of electronic filters are linear filters, regardless of other aspects of their design. See the article on linear filters for details on their design and analysis.
Contents
[hide]- 1 History
- 2 Classification by technology
- 3 The transfer function
- 4 Classification by topology
- 5 Classification by design methodology
- 6 See also
- 7 External links and references
بقیه و متن کامل مقاله در ادامه ی مطالب...
ادامه مطلب...
Electric power distribution
 |
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (January 2008) |
Electricity distribution is the final stage in the delivery (before retail) of electricity to end users. A distribution system's network carries electricity from the transmission system and delivers it to consumers. Typically, the network would include medium-voltage (less than 50 kV) power lines, electrical substations and pole-mounted transformers, low-voltage (less than 1 kV) distribution wiring and sometimes electricity meters.
Contents
[hide]- 1 Modern distribution systems
- 2 History
- 3 Distribution network configurations
- 4 Distribution industry
- 5 See also
- 6 References
- 7 External links
- 8 Further reading
بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Electrical conductor
 |
This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2009) |
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors, such as copper or aluminum, the movable charged particles are electrons (see electrical conduction). Positive charges may also be mobile in the form of atoms in a lattice that are missing electrons (known as holes), or in the form of ions, such as in the electrolyte of a battery. Insulators are non-conducting materials with fewer mobile charges, which resist the flow of electric current.
All conductors contain electric charges which will move when an electric potential difference (measured in volts) is applied across separate points on the material. This flow of charge (measured in amperes) is what is meant by electric current. In most materials, the direct current is proportional to the voltage (as determined by Ohm's law), provided the temperature remains constant and the material remains in the same shape and state.
Most familiar conductors are metallic. Copper is the most common material used for electrical wiring. Silver is the best conductor, but is expensive. Because it does not corrode, gold is used for high-quality surface-to-surface contacts. However, there are also many non-metallic conductors, including graphite, solutions of salts, and all plasmas. There are even conductive polymers. See electrical conduction for more information on the physical mechanism for charge flow in materials.
All non-superconducting materials offer some resistance and warm up when a current flows. Thus, proper design of an electrical conductor takes into account the temperature that the conductor needs to be able to endure without damage, as well as the quantity of electric current. The motion of charges also creates an electromagnetic field around the conductor that exerts a mechanical radial squeezing force on the conductor. A conductor of a given material and volume (length × cross-sectional area) has no real limit to the current it can carry without being destroyed as long as the heat generated by the resistive loss is removed and the conductor can withstand the radial forces. This effect is especially critical in printed circuits, where conductors are relatively small and close together, and inside an enclosure: the heat produced, if not properly removed, can cause fusing (melting) of the tracks.
Thermal and electrical conductivity often go together. For instance, most metals are both electrical and thermal conductors. However, some materials are practical electrical conductors without being good thermal conductors.
Contents
[hide]بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Intel Corporation
 |
|
| Type | Public |
|---|---|
| Traded as | NASDAQ: INTC NYSE: INTC SEHK: 4335 Euronext: INCO Dow Jones Industrial Average Component NASDAQ-100 Component |
| Industry | Semiconductors |
| Founded | Mountain View, California (1968)[1] |
| Founder(s) | Gordon E. Moore Robert Noyce |
| Headquarters | Santa Clara, California, U.S.[2] |
| Area served | Worldwide |
| Key people | Jane E. Shaw (Chairman) Paul S. Otellini (President and CEO) |
| Products | Microprocessors Flash memory Motherboard Chipsets Network Interface Card Bluetooth Chipsets |
| Revenue |  US$ 43.623 billion (2010)[3] |
| Operating income | US$ 16.045 billion (2010)[3] |
| Net income | US$ 11.464 billion (2010)[3] |
| Total assets | US$ 63.186 billion (2010)[3] |
| Total equity | US$ 49.430 billion (2010)[3] |
| Employees | 82,500 (January 2010)[3] |
| Website | Intel.com |
Intel Corporation (NASDAQ: INTC) is an American global technology company and the world's largest semiconductor chip maker, based on revenue.[4] It is the inventor of the x86 series of microprocessors, the processors found in most personal computers. Intel was founded on July 18, 1968, as Integrated Electronics Corporation (though a common misconception is that "Intel" is from the word intelligence) and is based in Santa Clara, California, USA. Intel also makes motherboard chipsets, network interface controllers and integrated circuits, flash memory, graphic chips, embedded processors and other devices related to communications and computing. Founded by semiconductor pioneers Robert Noyce and Gordon Moore and widely associated with the executive leadership and vision of Andrew Grove, Intel combines advanced chip design capability with a leading-edge manufacturing capability. Though Intel was originally known primarily to engineers and technologists, its "Intel Inside" advertising campaign of the 1990s made it and its Pentium processor household names.
Intel was an early developer of SRAM and DRAM memory chips, and this represented the majority of its business until 1981. While Intel created the first commercial microprocessor chip in 1971, it was not until the success of the personal computer (PC) that this became its primary business. During the 1990s, Intel invested heavily in new microprocessor designs fostering the rapid growth of the computer industry. During this period Intel became the dominant supplier of microprocessors for PCs, and was known for aggressive and sometimes controversial tactics in defense of its market position, particularly against AMD, as well as a struggle with Microsoft for control over the direction of the PC industry.[5][6] The 2010 rankings of the world's 100 most powerful brands published by Millward Brown Optimor showed the company's brand value at number 48.[7]
Intel has also begun research in electrical transmission and generation.[8][9]
Contents
[hide]- 1 Corporate history
- 2 Product and market history
- 3 Corporate affairs
- 4 Competition
- 5 See also
- 6 References
- 7 External links
بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Microprocessor
A microprocessor incorporates most or all of the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC, or microchip).[1][2]
The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal (BCD) arithmetic on 4-bit words. Other embedded uses of 4-bit and 8-bit microprocessors, such as terminals, printers, various kinds of automation etc., followed soon after. Affordable 8-bit microprocessors with 16-bit addressing also led to the first general-purpose microcomputers from the mid-1970s on.
During the 1960s, computer processors were often constructed out of small and medium-scale ICs containing from tens to a few hundred transistors. The integration of a whole CPU onto a single chip greatly reduced the cost of processing power. From these humble beginnings, continued increases in microprocessor capacity have rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessors used in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.
Since the early 1970s, the increase in capacity of microprocessors has followed Moore's law, which suggests that the number of transistors that can be fitted onto a chip doubles every two years. Although originally calculated as a doubling every year,[3] Moore later refined the period to two years.[4] It is often incorrectly quoted as a doubling of transistors every 18 months.
Contents
[hide]- 1 Firsts
- 2 8-bit designs
- 3 12-bit designs
- 4 16-bit designs
- 5 32-bit designs
- 6 64-bit designs in personal computers
- 7 Multicore designs
- 8 RISC
- 9 Special-purpose designs
- 10 Market statistics
- 11 See also
- 12 Notes and references
- 13 External links
بقیه و متن کامل در ادامه مطالب...
ادامه مطلب...
Sonar
Sonar (originally an acronym for SOund Navigation And Ranging) is a technique that uses sound propagation (usually underwater, as in Submarine navigation) to navigate, communicate with or detect other vessels. Two types of technology share the name "sonar": passive sonar is essentially listening for the sound made by vessels; active sonar is emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used in air for robot navigation, and SODAR (an upward looking in-air sonar) is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of underwater sound is known as underwater acoustics or hydroacoustics.
Contents
[hide]- 1 History
- 2 Performance factors
- 3 Active sonar
- 4 Passive sonar
- 5 Warfare
- 6 Civilian applications
- 7 Scientific applications
- 8 See also
- 9 References
- 10 Bibliography
- 11 Further reading
- 12 External links
بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Television
Television (TV) is a telecommunication medium for transmitting and receiving moving images that can be monochromatic (shades of grey) or multicolored. Images are usually accompanied by sound. "Television" may also refer specifically to a television set, television programming, television transmission.
The etymology of the word is derived from mixed Latin and Greek origin, meaning "far sight": Greek tele (τῆλε), far, and Latin visio, sight (from video, vis- to see, or to view in the first person.
Commercially available since the late 1920s, the television set has become commonplace in homes, businesses and institutions, particularly as a source of entertainment and news. Since the 1970s the availability of video cassettes, laserdiscs, DVDs and now Blu-ray Discs, have resulted in the television set frequently being used for viewing recorded as well as broadcast material. In recent years Internet television has seen the rise of television available via the Internet, e.g. iPlayer and Hulu.
Although other forms such as closed-circuit television (CCTV) are in use, the most common usage of the medium is for broadcast television, which was modeled on the existing radio broadcasting systems developed in the 1920s, and uses high-powered radio-frequency transmitters to broadcast the television signal to individual TV receivers.
Broadcast TV is typically disseminated via radio transmissions on designated channels in the 54–890 MHz frequency band.[1] Signals are now often transmitted with stereo and/or surround sound in many countries. Until the 2000s broadcast TV programs were generally transmitted as an analogue television signal, but in recent years public and commercial broadcasters have been progressively introducing digital television broadcasting technology.
A standard television set comprises multiple internal electronic circuits, including those for receiving and decoding broadcast signals. A visual display device which lacks a tuner is properly called a monitor, rather than a television. A television system may use different technical standards such as digital television (DTV) and high-definition television (HDTV). Television systems are also used for surveillance, industrial process control, and guiding of weapons, in places where direct observation is difficult or dangerous.
Amateur television (ham TV or ATV) is also used for experimentation, pleasure and public service events by amateur radio operators. Ham TV stations were on the air in many cities before commercial TV stations came on the air.[2]
Contents
[hide]- 1 History
- 2 Geographical usage
- 3 Content
- 4 Social aspects and effects on children
- 5 Environmental aspects
- 6 See also
- 7 References
- 8 Further reading
- 9 External links
بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Telegraphy
| ) |
Telegraphy is the long-distance transmission of messages without physical transport of written messages. It is a compound term formed from the Greek words tele (τηλε) = far and graphein (γραφειν) = write. Radiotelegraphy or wireless telegraphy transmits messages using radio.
Contents
[hide]- 1 Terminology
- 2 Optical telegraph
- 3 Electrical telegraphs
- 4 Wireless telegraphy
- 5 Telegraphic improvements
- 6 Telex
- 7 Arrival of the Internet
- 8 E-mail displaces telegraphy
- 9 Worldwide status of telegram services
- 10 Social implications
- 11 Names of periodicals
- 12 See also
- 13 References
- 14 Further reading
- 15 External links
بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Telephone
- "Phone" redirects here. For other uses, see Phone (disambiguation). This article is about the communications device. For other uses, see Telephone (disambiguation).
| Phone | |
|---|---|
 |
|
| An Olivetti rotary dial telephone, c.1940s |
The telephone (from the Greek: τῆλε, tēle, "far" and φωνή, phōnē, "voice"), often colloquially referred to as a phone, is a telecommunications device that transmits and receives sound, most commonly the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other. It is one of the most common appliances in the developed world, and has long been considered indispensable to businesses, households and governments. The word "telephone" has been adapted to many languages and is widely recognized around the world.
All telephones have a microphone to speak into, an earphone which reproduces the voice of the other person, a ringer which makes a sound to alert the owner when a call is coming in, and a keypad (or in older phones a telephone dial or no manual device) to enter the telephone number of the telephone being called. The microphone and earphone are usually built into a handset which is held up to the face to talk. The keypad may be part of the handset or of a base unit to which the handset would be connected. A landline telephone is connected by a pair of wires to the telephone network, while a mobile phone or cell phone is portable and communicates with the telephone network by radio. A cordless telephone has a portable handset which communicates by radio with a base station connected by wire to the telephone network, and can only be used within a limited range of the base station.
The microphone converts the sound waves to electrical signals, which are sent through the telephone network to the other phone, where they are converted back to sound waves by the earphone in the other phone's handset. Telephones are a duplex communications medium, meaning they allow the people on both ends to talk simultaneously. The telephone network, consisting of a worldwide net of telephone lines, fiberoptic cables, microwave transmission, cellular networks, communications satellites, and undersea telephone cables connected by switching centers, allows any telephone in the world to communicate with any other. Each telephone line has an identifying number called its telephone number. To initiate a telephone call, a conversation with another telephone, the user enters the other telephone's number into a numeric keypad on his/her phone. Graphic symbols used to designate telephone service or phone-related information in print, signage, and other media include ℡ (U+2121), ☎ (U+260E), ☏ (U+260F), and ✆ (U+2706).
Although originally designed for voice communication, the system has been adapted for data communication such as Telex, Fax and dial-up Internet communication.
Contents
[hide]- 1 History
- 2 Basic principles
- 3 Details of operation
- 4 Digital telephony
- 5 IP telephony
- 6 Usage
- 7 Telephone operating companies
- 8 Patents
- 9 See also
- 10 Notes
- 11 References
- 12 Further reading
- 13 External links
بقیه و متن کامل مقاله در ادامه مطالب...
ادامه مطلب...
Control system
A control system is a device or set of devices to manage, command, direct or regulate the behavior of other devices or systems.
There are two common classes of control systems, with many variations and combinations: logic or sequential controls, and feedback or linear controls. There is also fuzzy logic, which attempts to combine some of the design simplicity of logic with the utility of linear control. Some devices or systems are inherently not controllable.
Contents
[hide]- 1 Overview
- 2 Logic control
- 3 On–off control
- 4 Linear control
- 5 Fuzzy logic
- 6 Physical implementations
- 7 See also
- 8 References
- 9 External links
ادامه مطلب...
