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top 10 words in brain distribution (in article): time beam common type state allow company production form term |
top 10 words in brain distribution (in article): century design style modern allow time american popular english common |
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top 10 words in brain distribution (not in article): light drink species lamp water wine beer produce bottle plant |
top 10 words in brain distribution (not in article): wear horse woman clothe saddle material dress fashion type ride |
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times more probable under key 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under telephone (words not in the model) | |
| A key'" is a device which is used to open a lock. A typical key consist of two parts: the "blade", which slides into the keyway of the lock and distinguishes between different keys, and the "bow", which is left protruding so that torque can be applied by the user. The blade is usually designed to open one specific lock, although master keys are designed to open sets of similar locks. Keys provide an inexpensive, though imperfect, method of authentication for access to properties like buildings and vehicles. As such, keys are an essential feature of modern living in the developed world, aing adorned by key fobs and known as a keychain. House keys. A house key'" is the most common sort of key. There are two main forms. The older form is for lever locks, where a pack of flat levers (typically between two and five) are raised to different heights by the key whereupon the slots or "'gates'" of the levers line up and permit a bolt to move back and forth, opening or closing the lock. The teeth or "'bittings'" of the key have flat tops rather than being pointed. Lever lock keys tend to be bigger and less convenient for carrying, although lever locks tend to be more secure. These are still common in, for example, many European countries. The more recent form is that for a pin tumbler cylinder lock. When held upright as if to open a door, a series of grooves on either side of the key (the key's "'profile'") limits the type of lock cylinder the key can slide into. As the key slides into the lock, a series of pointed teeth and notches allow pins to move up and down until those pins are in line with the shear line of the cylinder, allowing that cylinder to rotate freely inside the lock and the lock to open. These predominate in, for example, the United States of America. Car key. A "'car key'" or an "'automobile key'" is a key used to open and or start an automobile, often identified with the logo of the car company at the head. Modern key designs are usually symmetrical, and some use grooves on both sides, rather than a cut edge, to actuate the lock. It has multiple uses for the automobile with which it was sold. A car key can open the doors, as well as start the ignition, open the glove compartment and also open the trunk (boot) of the car. Some cars come with an additional key known as a "'valet key'" that starts the ignition and opens the drivers side door but prevents the valet from gaining access to valuables that are located in the trunk or the glove box. Some valet keys, particularly those to high-performance vehicles, go so far as to restrict the engine's power output to prevent joyriding. Recently, features such as coded immobilizers have been implemented in newer vehicles. More sophisticated systems make ignition dependent on electronic devices, rather than the mechanical keyswitch. Ignition switches locks are combined with security locking of the steering column (in many modern vehicles) or the gear lever (Saab Automobile). In the latter, the switch is between the seats, preventing damage to the driver's knee in the event of a collision. Keyless entry systems, which utilize either a door-mounted keypad or a remote control in place of a car key, are becoming a standard feature on many new cars. Some of them are handsfree. Some keys are high-tech in order to prevent the theft of a car. Mercedes-Benz uses a key that, rather than have a cut metal piece to start the car, uses an encoded infrared beam that communicates with the car's computer. If the codes match, the car can be started. These keys can be expensive to replace, if lost, and can cost up to US$400. Some car manufacturers like Land Rover and Volkswagen use a 'switchblade' key where the key is spring-loaded out of the fob when a button is pressed. This eliminates the need for a separate key fob. This type of key has also been known to be confiscated by airport security officials. Master key. A "'master key'" is intended to open a set of several locks. Usually, there is nothing special about the key itself, but rather the locks into which it will fit. These locks also have keys which are specific to each one (the "'change key'") and cannot open any of the others in the set. Locks which have master keys have a second set of the mechanism used to open them which is identical to all of the others in the set of locks. For example, master keyed pin tumbler locks will have two shear points at each pin position, one for the change key and one for the master key. A far more secure (and more expensive) system has two cylinders in each lock, one for the change key and one for the master key. Larger organizations, with more complex "grandmaster key" systems, may have several masterkey systems where the top level grandmaster key works in all of the locks in the system. A practical attack exists to create a working master key for an entire system given only access to a single master-keyed lock, its associated change key, a supply of appropriate key blanks, and the ability to cut new keys. This is described in Locksmiths may also determine cuts for a replacement master key, when given several different key examples from a given system. Control key. A "'control key'" is a special key used in removable core locking systems. The control key enables a user with very little skill to remove from the cylinder, quickly and easily, a core with a specific combination and replace it with a core with a different combination. In Small Format Interchangeable Cores (SFIC), similar to those developed by Frank Best of the Best Lock Corporation, the key operates a separate shear line, located above the operating key shear line. In Large Format Removable Cores, the key may operate a separate shear line or the key may work like a master key along the operating shear line and also contact a separate locking pin that holds the core in the cylinder. SFIC's are interchangeable from one brand to another, while LFRC's are not. Double-sided key. A "'double-sided key'" is very similar to a house or car key with the exception that it has two sets of teeth, an upper level standard set of teeth and a lower, less defined set of teeth beside it. This makes the double-sided key's profile and its corresponding lock look very similar to a standard key while making the attempt to pick the lock more difficult. As the name implies, this type of key has four sides, making it not only harder to duplicate and the lock harder to pick, but it is also physically more durable. Paracentric key. A "'paracentric key'" is designed to open a paracentric lock. It is distinguishable by the contorted shape of its blade, which protrudes past the centre vertical line of the key barrel. Instead of the wards on the outer face of the lock simply protruding into the shape of the key along the spine, the wards protrude into the shape of the key along the entire width of the key, including along the length of the teeth. Patented by the Yale lock company in 1898, paracentric cylinders are not exceptionally difficult to pick, but require some skill and know-how on the part of the person attempting to pick the lock. Skeleton key=== A "'skeleton key'" (or "'passkey'") is a very simple design of key which usually has a cylindrical shaft (sometimes called a "shank") and a single, minimal flat, rectangular tooth or "bit". Skeleton keys are also usually distinguished by their "bow", or the part one would grasp when inserting the key, which can be either very plain or extremely ornate. A skeleton key is designed to circumvent the wards in warded locks. Warded locks and their keys provide minimal security and only a slight deterrent as any key with a shaft and tooth that has the same or smaller dimensions will open the lock. However, warded keys were designed to only fit a matching lock and the skeleton key would often fit many. Many other objects which can fit into the lock may also be able to open it. Due to its limited usefulness, this type of lock fell out of use after more complicated types became easier to manufacture. In modern usage, the term "skeleton key" is often misapplied to ordinary bit keys and barrel keys, rather than the correct definition: a key, usually with minimal features, which can open all or most of a type of badly designed lock. Bit keys and barrel keys can be newly-minted (and sold by restoration hardware companies) or antiques. They were most popular in the late 1800s, although they continued to be used well into the 20th century and can still be found today in use, albeit in vintage homes and antique furniture. A bit key is distinguished from a barrel key in that a bit key usually has a solid shank, whereas a barrel shafted key can be made either by drilling out the shank from the bit end or by folding metal into a barrel shape when forging the key. Tubular key. A tubular key'" (sometimes referred to as a "barrel key" when describing a vintage or antique model) is one that is designed to open a tubular pin tumbler lock. It has a hollow, cylindrical shaft which is usually much shorter and has a larger diameter than most conventional keys. Antique or vintage-style barrel keys often closely resemble the more traditional "skeleton key" but are a more recent innovation in keymaking. In modern keys of this type, a number of grooves of varying length are built into the outer surface at the end of the shaft. These grooves are parallel to the shaft and allow the pins in the lock to slide to the end of the groove. A small tab on the outer surface of the shaft prevents the pins in the lock from pushing the key out and works with the hollow center to guide the key as it is turned. The modern version of this type of key is harder to duplicate as it is less common and requires a different machine from regular keys. These keys are most often seen in home alarm systems and bicycle locks, in the United States. Zeiss key. A Zeiss key'" (also known as a "'Cruciform key'") is a cross between a house key and a tubular key. It has three sets of teeth at 90 degrees to each other with a flattened fourth side. Though this type of key is easy to duplicate, the extra sets of teeth deter lockpicking attempts. Do Not Duplicate key. A "'Do Not Duplicate key'" (or "'DND key'", for short) is one which has been stamped "do not duplicate" and or "duplication prohibited" or similar by a locksmith or manufacturer as a passive deterrent to prevent a retail key cutting service from duplicating a key without authorization or without contacting the locksmith or manufacturer who originally cut the key. More importantly, this is an access control system for the owner of the key, such as a maintenance person or security guard, to identify keys that should not be freely distributed or used without authorization. Though it is intended to prevent unauthorized key duplication, copying restricted keys remains a common security problem. There is no direct legal implication in the US for someone who copies a key that is stamped "do not duplicate" (unless it is a government owned key), but there are patent restrictions on some key designs (see "restricted keys"). The Associated Locksmiths of America calls DND keys "not effective security", and "deceptive because it provides a false sense of security." United States Code deals with United States Post Office keys, and deals with United States Department of Defense keys. Restricted key. A restricted keyblank'" is a keyway and blank for which a manufacturer has set up a restricted level of sales and distribution. Restricted keys are often protected by patent, which prohibits other manufacturers from making unauthorized productions of the key blank. In many jurisdictions, customers must provide proof of ID before a locksmith will duplicate a key using a restricted blank. These days, many restricted keys have special in-laid features, such as magnets, different types of metal, or even small computer chips to prevent duplication. Keycard. A "'keycard'", while not actually considered a key, is a plastic card which stores a digital signature that is used with electronic access control locks. It is normally a flat, rectangular piece of plastic and may also serve as an ID card. There are several popular type of keycards in use and include the mechanical holecard, bar code, magnetic stripe, smart card (embedded with a read write electronic microchip), and RFID proximity cards. The keycard is used by presenting it to a card reader; swiping or inserting of mag stripe cards, or in the case of RFID cards, merely being brought into close proximity to a sensor. Bar code technology is not a secure form of a key, as the bar code can be copied in a photocopier and often read by the optical reader. Magnetic stripe keycards are becoming increasingly easy to copy, but have the security advantage that one may change the stored key in a magnetic swipe card in case the current key may be | The telephone'" (from the, "tēle", "far" and φωνή, "phōnē", "voice") is a telecommunications device that is used to transmit and receive electronically or digitally encoded sound (most commonly speech) between two or more people conversing. It is one of the most common household appliances in the developed world today. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost any other user. Graphic symbols used to designate telephone service or phone-related information in print, signs, and other media include,, and. Basic principle. A traditional landline telephone system, also known as "plain old telephone service" (POTS), commonly handles both signaling and audio information on the same twisted pair of insulated wires: the telephone line. Although originally designed for voice communication, the system has been adapted for data communication such as Telex, Fax and Internet communication. The signaling equipment consists of a bell, beeper, light or other device to alert the user to incoming calls, and number buttons or a rotary dial to enter a telephone number for outgoing calls. A twisted pair line is preferred as it is more effective at rejecting electromagnetic interference (EMI) and crosstalk than an untwisted pair. A calling party wishing to speak to another party will pick up the telephone's handset, thus operating a button switch or "switchhook", which puts the telephone into an active state or "off hook" by connecting the transmitter (microphone), receiver (speaker) and related audio components to the line. This circuitry has a low resistance (less than 300 Ohms) which causes DC current (48 volts, nominal) from the telephone exchange to flow through the line. The exchange detects this DC current, attaches a digit receiver circuit to the line, and sends a dial tone to indicate readiness. On a modern telephone, the calling party then presses the number buttons in a sequence corresponding to the telephone number of the called party. The buttons are connected to a tone generator that produces DTMF tones which are sent to the exchange. A rotary dial telephone employs pulse dialing, sending electrical pulses corresponding to the telephone number to the exchange. (Most exchanges are still equipped to handle pulse dialing.) Provided the called party's line is not already active or "busy", the exchange sends an intermittent ringing signal (generally over 100 volts AC) to alert the called party to an incoming call. If the called party's line is active, the exchange sends a busy signal to the calling party. However, if the called party's line is active but has call waiting installed, the exchange sends an intermittent audible tone to the called party to indicate an incoming call. When a landline phone is inactive or "on hook", its alerting device is connected across the line through a capacitor, which prevents DC current from flowing through the line. The circuitry at the telephone exchange detects the absence of DC current flow and thus that the phone is on hook with only the alerting device electrically connected to the line. When a party initiates a call to this line, the ringing signal transmitted by the telephone exchange activates the alerting device on the line. When the called party picks up the handset, the switchhook disconnects the alerting device and connects the audio circuitry to the line. The resulting low resistance now causes DC current to flow through this line, confirming that the called phone is now active. Both phones being active and connected through the exchange, the parties may now converse as long as both phones remain off hook. When a party "hangs up", placing the handset back on the cradle or hook, DC current ceases to flow in that line, signaling the exchange to disconnect the call. Calls to parties beyond the local exchange are carried over "trunk" lines which establish connections between exchanges. In modern telephone networks, fiber-optic cable and digital technology are often employed in such connections. Satellite technology may be used for communication over very long distances. In most telephones, the transmitter and receiver (microphone and speaker) are located in the handset, although in a speakerphone these components may be located in the base or in a separate enclosure. Powered by the line, the transmitter produces an electric current whose voltage varies in response to the sound waves arriving at its diaphragm. The resulting current is transmitted along the telephone line to the local exchange then on to the other phone (via the local exchange or a larger network), where it passes through the coil of the receiver. The varying voltage in the coil produces a corresponding movement of the receiver's diaphragm, reproducing the sound waves present at the transmitter. A Lineman's handset is a telephone designed for testing the telephone network, and may be attached directly to aerial lines and other infrastructure components. History. Credit for inventing the electric telephone remains in dispute. As with other great inventions such as radio, television, light bulb, and computer, there were several inventors who did pioneer experimental work on voice transmission over a wire and improved on each other's ideas. Innocenzo Manzetti, Antonio Meucci, Johann Philipp Reis, Elisha Gray, Alexander Graham Bell, and Thomas Edison, among others, have all been credited with pioneer work on the telephone. A Hungarian engineer, Tivadar Puskás invented the Telephone exchange in 1876. The early history of the telephone is a confusing morass of claim and counterclaim, which was not clarified by the huge mass of lawsuits which hoped to resolve the patent claims of individuals. The Bell and Edison patents, however, were forensically victorious and commercially decisive. Early commercial instruments. Early telephones were technically diverse. Some used a liquid transmitter, some had a metal diaphragm that induced current in an electromagnet wound around a permanent magnet, and some were "dynamic" -their diaphragm vibrated a coil of wire in the field of a permanent magnet or the coil vibrated the diaphragm. This dynamic kind survived in small numbers through the 20th century in military and maritime applications where its ability to create its own electrical power was crucial. Most, however, used the Edison Berliner carbon transmitter, which was much louder than the other kinds, even though it required an induction coil, actually acting as an impedance matching transformer to make it compatible to the impedance of the line. The Edison patents kept the Bell monopoly viable into the 20th century, by which time the network was more important than the instrument. Early telephones were locally powered, using either a dynamic transmitter or by the powering of a transmitter with a local battery. One of the jobs of outside plant personnel was to visit each telephone periodically to inspect the battery. During the 20th century, "common battery" operation came to dominate, powered by "talk battery" from the telephone exchange over the same wires that carried the voice signals. Early telephones used a single wire for the subscriber's line, with ground return used to complete the circuit (as used in telegraphs). The earliest dynamic telephones also had only one opening for sound, and the user alternately listened and spoke (rather, shouted) into the same hole. Sometimes the instruments were operated in pairs at each end, making conversation more convenient but were more expensive. At first, the benefits of an exchange were not exploited. Telephones instead were leased in pairs to the subscriber, who had to arrange telegraph contractors to construct a line between them, for example between his home and his shop. Users who wanted the ability to speak to several different locations would need to obtain and set up three or four pairs of telephones. Western Union, already using telegraph exchanges, quickly extended the principle to its telephones in New York City and San Francisco, and Bell was not slow in appreciating the potential. Signalling began in an appropriately primitive manner. The user alerted the other end, or the exchange operator, by whistling into the transmitter. Exchange operation soon resulted in telephones being equipped with a bell, first operated over a second wire, and later over the same wire, but with a condenser (capacitor) in series with the bell coil to allow the AC ringer signal through while still blocking DC (keeping the phone "on hook"). Telephones connected to the earliest Strowger automatic exchanges had seven wires, one for the knife switch, one for each telegraph key, one for the bell, one for the push button and two for speaking. Rural and other telephones that were not on a common battery exchange had a magneto or hand-cranked generator to produce a high voltage alternating signal to ring the bells of other telephones on the line and to alert the operator. In the 1890s a new smaller style of telephone was introduced, packaged in three parts. The transmitter stood on a stand, known as a "candlestick" for its shape. When not in use, the receiver hung on a hook with a switch in it, known as a "switchhook." Previous telephones required the user to operate a separate switch to connect either the voice or the bell. With the new kind, the user was less likely to leave the phone "off the hook". In phones connected to magneto exchanges, the bell, induction coil, battery and magneto were in a separate "bell box." In phones connected to common battery exchanges, the bell box was installed under a desk, or other out of the way place, since it did not need a battery or magneto. Cradle designs were also used at this time, having a handle with the receiver and transmitter attached, separate from the cradle base that housed the magneto crank and other parts. They were larger than the "candlestick" and more popular. Disadvantages of single wire operation such as crosstalk and hum from nearby AC power wires had already led to the use of twisted pairs and, for long distance telephones, four-wire circuits. Users at the beginning of the 20th century did not place long distance calls from their own telephones but made an appointment to use a special sound proofed long distance telephone booth furnished with the latest technology. What turned out to be the most popular and longest lasting physical style of telephone was introduced in the early 20th century, including Bell's Model 102. A carbon granule transmitter and electromagnetic receiver were united in a single molded plastic handle, which when not in use sat in a cradle in the base unit. The of the Model 102 shows the direct connection of the receiver to the line, while the transmitter was induction coupled, with energy supplied by a local battery. The coupling transformer, battery, and ringer were in a separate enclosure. The dial switch in the base interrupted the line current by repeatedly but very briefly disconnecting the line 1-10 times for each digit, and the hook switch (in the center of the circuit diagram) permanently disconnected the line and the transmitter battery while the handset was on the cradle. After the 1930s, the base also enclosed the bell and induction coil, obviating the old separate bell box. Power was supplied to each subscriber line by central office batteries instead of a local battery, which required periodic service. For the next half century, the network behind the telephone became progressively larger and much more efficient, but after the dial was added the instrument itself changed little until touch tone replaced the dial in the 1960s. Digital telephony. The Public Switched Telephone Network (PSTN) has gradually evolved towards digital telephony which has improved the capacity and quality of the network. End-to-end analog telephone networks were first modified in the early 1960s by upgrading transmission networks with T1 carrier systems. Later technologies such as SONET and fiber optic transmission methods further advanced digital transmission. Although analog carrier systems existed, digital transmission made it possible to significantly increase the number of channels multiplexed on a single transmission medium. While today the end instrument remains analog, the analog signals reaching the aggregation point (Serving Area Interface (SAI) or the central office (CO)) are typically converted to digital signals. Digital loop carriers (DLC) are often used, placing the digital network ever closer to the customer premises, relegating the analog local loop to legacy status. IP telephony. Internet Protocol (IP) telephony (also known as Voice over Internet Protocol, VoIP), is a disruptive technology that is rapidly gaining ground against traditional telephone network technologies. As of January 2005, up to 10% of telephone subscribers in Japan and South Korea have switched to this digital telephone service. A January 2005 Newsweek article suggested that Internet telephony may be "the next big thing." As of 2006 many VoIP companies offer service to consumers and businesses. IP telephony uses an Internet connection and hardware IP Phones or softphones installed on personal computers to transmit conversations encoded as data packets. In addition to replacing POTS (plain old telephone service), IP telephony services are also competing with mobile phone services by offering free or lower cost connections via WiFi hotspots. VoIP is also used on private networks which may or may not have a connection to the global telephone network. Usage. By the end of 2006, there were a total of nearly 4 billion mobile and fixed-line subscribers and over 1 billion Internet users worldwide. This included 1.27 billion fixed-line subscribers and 2.68 billion mobile subscribers. Telephone operating companies. In some countries, many telephone operating companies (commonly abbreviated to "telco" in American English) are in competition to provide telephone services. Some of them are included in the following list. However, the list only includes facilities based providers and not companies which lease services from facilities based providers in order to serve their customers. |