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Loop Detector
An induction or inductive loop is an electromagnetic communication or detection system which uses a moving magnet or an alternating current to induce an electric current in a nearby wire. Induction loops are used for transmission and reception of communication signals, or for detection of metal objects in metal detectors or vehicle presence indicators. A common modern use for induction loops is to provide hearing assistance to hearing-aid users. Applications Vehicle detection Vehicle detection loops, called ''inductive-loop traffic detectors'', can detect vehicles passing or arriving at a certain point, for instance approaching a traffic light or in motorway traffic. An insulated, electrically conducting loop is installed in the pavement. The electronics unit applies alternating current electrical energy onto the wire loops at frequencies between 10 k Hz to 200 kHz, depending on the model. The inductive-loop system behaves as a tuned electrical circuit in which t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetism
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena. Electromagnetic forces occur between any two charged particles. Electric forces cause an attraction between particles with opposite charges and repulsion between particles with the same charge, while magnetism is an interaction that occurs between charged particles in relative motion. These two forces are described in terms of electromagnetic fields. Macroscopic charged objects are described in terms of Coulomb's law for electricity and Ampère's force law for magnetism; the Lorentz force describes microscopic charged particles. The electromagnetic force is responsible for ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Detector
A metal detector is an instrument that detects the nearby presence of metal. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector consists of a control box, an adjustable shaft, and a variable-shaped pickup coil. When the coil nears metal, the control box signals its presence with a tone, numerical reading, light, or needle movement. Signal intensity typically increases with proximity and/or metal size/composition. A common type are stationary "walk through" metal detectors used at access points in prisons, courthouses, airports and psychiatric hospitals to detect concealed metal weapons on a person's body. The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field. If a piece of electrically conductive metal is close to the coil, eddy currents will be induced ( inductive sensor) in the metal, and this produces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Components
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena. Electromagnetic forces occur between any two charged particles. Electric forces cause an attraction between particles with opposite charges and repulsion between particles with the same charge, while magnetism is an interaction that occurs between charged particles in relative motion. These two forces are described in terms of electromagnetic fields. Macroscopic charged objects are described in terms of Coulomb's law for electricity and Ampère's force law for magnetism; the Lorentz force describes microscopic charged particles. The electromagnetic force is responsible for ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
How Stuff Works
HowStuffWorks is an American commercial infotainment website founded by professor and author Marshall Brain, to provide its target audience an insight into the way many things work. The site uses various media to explain complex concepts, terminology, and mechanisms—including photographs, diagrams, videos, animations, and articles. The website was acquired by Discovery Communications in 2007, but was sold to Blucora in 2014. The site has since expanded out into podcasting, focusing on factual topics. In December 2016, HowStuffWorks, LLC became a subsidiary of OpenMail, LLC, later renamed System1. In 2018, the podcast division of the company, which had been spun-off by System1 under the name Stuff Media, was acquired by iHeartMedia for $55 million. History In 1998, then North Carolina State University instructor Marshall Brain (1961–2024), started the site as a hobby. In 1999, Brain raised venture capital and formed HowStuffWorks, Inc. In March 2002, HowStuffWorks was so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sydney Coordinated Adaptive Traffic System
The Sydney Coordinated Adaptive Traffic System, abbreviated SCATS, is an intelligent transportation system that manages the dynamic (on-line, real-time) timing of signal phases at traffic signals, meaning that it tries to find the best phasing (i.e. cycle times, phase splits and offsets) for a traffic situation (for individual intersections as well as for the whole network). SCATS is based on the automatic plan selection from a library in response to the data derived from loop detectors or other road traffic sensors. SCATS uses sensors at each traffic signal to detect vehicle presence in each lane and pedestrians waiting to cross at the local site. The vehicle sensors are generally inductive loops installed within the road pavement. These are unable to detect bicycles. The pedestrian sensors are usually push buttons. Various other types of sensors can be used for vehicle presence detection, provided that a similar and consistent output is achieved. Information collected from the ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inductive Sensor
An inductive sensor is an electronic device that operates based on the principle of electromagnetic induction to detect or measure nearby metallic objects. An inductor develops a magnetic field when an electric current flows through it; alternatively, a current will flow through a circuit containing an inductor when the magnetic field through it changes. This effect can be used to detect metallic objects that interact with a magnetic field. Non-metallic substances, such as liquids or some kinds of dirt, do not interact with the magnetic field, so an inductive sensor can operate in wet or dirty conditions.Winncy Y. Du, ''Resistive, Capacitive, Inductive, and Magnetic Sensor Technologies'', CRC Press, 2014 , Chapter 4 ''Inductive Sensors'' Principle The inductive sensor is based on Faraday's law of induction. The temporal variations of the magnetic flux through a solenoid, coil with turns will induce a voltage which follows: : e = - N\frac which can be expressed in a simpler ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induction Coil
An induction coil or "spark coil" ( archaically known as an inductorium or Ruhmkorff coil after Heinrich Rühmkorff) is a type of transformer used to produce high-voltage pulses from a low-voltage direct current (DC) supply. p.98 To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called an interrupter. Invented in 1836 by the Irish-Catholic priest Nicholas Callan, also independently by American inventor Charles Grafton Page, the induction coil was the first type of transformer. It was widely used in x-ray machines, spark-gap radio transmitters, arc lighting and quack medical electrotherapy devices from the 1880s to the 1920s. Today its only common use is as the ignition coils in internal combustion engines and in physics education to demonstrate induction. Construction and function An induction coil consists of two coils of insulated wire wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hearing Aid
A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers such as personal sound amplification products (PSAPs) or other plain sound reinforcing systems cannot be sold as "hearing aids". Early devices, such as ear trumpets or ear horns, were passive amplification cones designed to gather sound energy and direct it into the ear canal. Modern devices are computerised electroacoustic systems that transform environmental sound to make it audible, according to audiometrical and cognitive rules. Modern devices also utilize sophisticated digital signal processing, aiming to improve speech intelligibility and comfort for the user. Such signal processing includes feedback management, wide dynamic range compression, directionality, frequency lowering, and noise reduction. Modern hearing aids requi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Induction Loop
An audio induction loop system (also called an audio-frequency induction loop or AFIL, or a hearing loop) is an assistive listening device for individuals with reduced ranges of hearing. History The first patented magnetic induction loop communication system was invented by Joseph Poliakoff (grandfather of Sir Martyn Poliakoff) in Great Britain in 1937. The pickup coil in a hearing aid is known as a '' telecoil'' (or ''T-coil'') because its early form was to pick up a magnetic field from coils within a telephone. These were included as a part of the method of enabling a two-way conversation over a single pair of wires. The telecoil enabled the hearing aid user to hear the phone conversation clearly without picking up background noise. From this, the natural development was to generate electromagnetic fields representing the audio, which the telecoil could receive. Design A hearing loop consists of one or more physical loops of cable which are placed around a designated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galvanometer
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely. Galvanometers work by deflecting a pointer in response to an electric current flowing through a coil in a constant magnetic field. The mechanism is also used as an actuator in applications such as hard disks. Galvanometers came from the observation, first noted by Hans Christian Ørsted in 1820, that a magnetic compass's needle deflects when near a wire having electric current. They were the first instruments used to detect and measure small amounts of current. André-Marie Ampère, who gave mathematical expression to Ørsted's discovery, named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk. G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine
A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or informally to refer to remotely operated vehicles and Autonomous underwater vehicle, robots, or to medium-sized or smaller vessels (such as the midget submarine and the wet sub). Submarines are referred to as ''boats'' rather than ''ships'' regardless of their size. Although experimental submarines had been built earlier, submarine design took off during the 19th century, and submarines were adopted by several navies. They were first used widely during World War I (1914–1918), and are now used in many navy, navies, large and small. Their military uses include: attacking enemy surface ships (merchant and military) or other submarines; aircraft carrier protection; Blockade runner, blockade running; Ballistic missile submarine, nuclear deterrenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-submarine Indicator Loop
An anti-submarine indicator loop was a submerged cable laid on the sea bed and used to detect the passage of enemy submarines. History In the early years of World War I submarines were fearful, one-sided weapons because they were invisible. In July 1915 Arthur Balfour replaced Winston Churchill as First Lord of the Admiralty. Balfour appreciated the importance of science, so he established a Board of Invention and Research (BIR), composed of a three-man central committee supported by an eminent consulting panel. The remits of Section II of the panel, the members of which included physicists Ernest Rutherford and William Henry Bragg, included anti-submarine measures. The panel concluded that the most promising approach was to listen for submarines, so they sought to improve hydrophones. Bragg soon moved to the hydrophone research centre HMS Tarlair at Aberdour on the Firth of Forth (which later relocated to Harwich in Essex). Independently from the BIR, in August 1915, a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
