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Karlqvist Gap
The Karlqvist gap or Karlqvist Field is an electromagnetic phenomenon discovered in 1953 by the Swedish engineer Olle Karlqvist (1922-1976), which is important in magnetic storage for computers. (HTML 1 kB) Karlqvist discovered the phenomenon while designing a ferromagnetic surface layer to the magnetic drum memory for the BESK computer. (HTML 3 kB) When designing a magnetic memory store, the ferromagnetic layer must be studied to determine the variation of the magnetic field with permeability, air gap, layer thickness and other influencing factors. The problem is non-linear and extremely difficult to solve. Karlqvist's gap discovery shows that the non-linear problem could be approximated by a linear boundary value for the two-dimensional static field and the one-dimensional transient field. This linear calculation gives a first approximation. Karlqvist published his discovery in the 1954 paper "Calculation of the magnetic field in ferromagnetic layer of a magnetic drum" at KTH ... [...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] |
Magnetic Storage
Magnetic storage or magnetic recording is the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetisation in a magnetizable material to store data and is a form of non-volatile memory. The information is accessed using one or more disk read-and-write head, read/write heads. Magnetic storage media, primarily Hard disk drive, hard disks, are widely used to store Data (computing), computer data as well as sound, audio and video signals. In the field of computing, the term ''magnetic storage'' is preferred and in the field of audio and video production, the term ''magnetic recording'' is more commonly used. The distinction is less technical and more a matter of preference. Other examples of magnetic storage media include floppy disks, magnetic tape, and magnetic stripe card, magnetic stripes on credit cards. History Magnetic storage in the form of wire recording—audio recording on a wire—was publicized by Oberlin Smith in the Sept 8, 1888 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferromagnetism
Ferromagnetism is a property of certain materials (such as iron) that results in a significant, observable magnetic permeability, and in many cases, a significant magnetic coercivity, allowing the material to form a permanent magnet. Ferromagnetic materials are noticeably attracted to a magnet, which is a consequence of their substantial magnetic permeability. Magnetic permeability describes the induced magnetization of a material due to the presence of an external magnetic field. For example, this temporary magnetization inside a steel plate accounts for the plate's attraction to a magnet. Whether or not that steel plate then acquires permanent magnetization depends on both the strength of the applied field and on the coercivity of that particular piece of steel (which varies with the steel's chemical composition and any heat treatment it may have undergone). In physics, multiple types of material magnetism have been distinguished. Ferromagnetism (along with the similar effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drum Memory
Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. Many early computers, called drum computers or drum machines, used drum memory as the main working memory of the computer. Some drums were also used as Auxiliary memory, secondary storage as for example various IBM_drum_storage, IBM drum storage drives and the UNIVAC FASTRAND series of drums. Drums were displaced as primary computer memory by magnetic core memory, which offered a better balance of size, speed, cost, reliability and potential for further improvements. Drums were then replaced by hard disk drives for secondary storage, which were both less expensive and offered denser storage. The manufacturing of drums ceased in the 1970s. Technical design A drum memory or drum storage unit contained a large metal cylinder, coated on the outside surface with a ferromagnetic recording material. It could be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BESK
BESK (''Binär Elektronisk SekvensKalkylator'', Swedish language, Swedish for "Binary Electronic Sequence Calculator") was Sweden's first electronic computer, using vacuum tubes instead of relays. It was developed by ''Matematikmaskinnämnden'' (Swedish Board for Computing Machinery) and for a short time it was the fastest computer in the world. The computer was completed in 1953 and in use until 1966. The technology behind BESK was later continued with the transistorized FACIT EDB and FACIT EDB-3 machines, both software compatible with BESK. Non-compatible machines highly inspired by BESK were SMIL (computer), SMIL made for the University of Lund, ''SAABs räkneautomat'' SARA (computer), SARA, "SAAB's calculating machine", and DASK made in Denmark. BESK was developed by the Swedish Board for Computing Machinery (Matematikmaskinnämnden) a few years after the mechanical relay computer BARK (computer), BARK (Binär Aritmetisk Relä-Kalkylator, Swedish for "Binary Arithmetic Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function (mathematics), function assigning a Euclidean vector, vector to each point of space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permeability (electromagnetism)
In electromagnetism, permeability is the measure of magnetization produced in a material in response to an applied magnetic field. Permeability is typically represented by the (italicized) Greek letter Mu (letter), ''μ''. It is the ratio of the Magnetic field, magnetic induction B to the magnetizing field H in a material. The term was coined by William Thomson, 1st Baron Kelvin in 1872, and used alongside permittivity by Oliver Heaviside in 1885. The reciprocal of permeability is magnetic reluctivity. In SI units, permeability is measured in Henry (unit), henries per Metre, meter (H/m), or equivalently in newton (unit), newtons per ampere squared (N/A2). The permeability constant ''μ''0, also known as the magnetic constant or the permeability of free space, is the proportionality between magnetic induction and magnetizing force when forming a magnetic field in a classical vacuum. A closely related property of materials is magnetic susceptibility, which is a Dimensionless ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear System
In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other scientists since most systems are inherently nonlinear in nature. Nonlinear dynamical systems, describing changes in variables over time, may appear chaotic, unpredictable, or counterintuitive, contrasting with much simpler linear systems. Typically, the behavior of a nonlinear system is described in mathematics by a nonlinear system of equations, which is a set of simultaneous equations in which the unknowns (or the unknown functions in the case of differential equations) appear as variables of a polynomial of degree higher than one or in the argument of a function which is not a polynomial of degree one. In other words, in a nonlinear system of equations, the equation(s) to be solved cannot be written as a lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boundary Value Problem
In the study of differential equations, a boundary-value problem is a differential equation subjected to constraints called boundary conditions. A solution to a boundary value problem is a solution to the differential equation which also satisfies the boundary conditions. Boundary value problems arise in several branches of physics as any physical differential equation will have them. Problems involving the wave equation, such as the determination of normal modes, are often stated as boundary value problems. A large class of important boundary value problems are the Sturm–Liouville problems. The analysis of these problems, in the linear case, involves the eigenfunctions of a differential operator. To be useful in applications, a boundary value problem should be well posed. This means that given the input to the problem there exists a unique solution, which depends continuously on the input. Much theoretical work in the field of partial differential equations is devot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetostatics
Magnetostatics is the study of magnetic fields in systems where the electric currents, currents are steady current, steady (not changing with time). It is the magnetic analogue of electrostatics, where the electric charge, charges are stationary. The magnetization need not be static; the equations of magnetostatics can be used to predict fast Magnetization reversal, magnetic switching events that occur on time scales of nanoseconds or less. Magnetostatics is even a good approximation when the currents are not static – as long as the currents do not alternating current, alternate rapidly. Magnetostatics is widely used in applications of micromagnetics such as models of magnetic storage devices as in computer memory. Applications Magnetostatics as a special case of Maxwell's equations Starting from Maxwell's equations and assuming that charges are either fixed or move as a steady current \mathbf, the equations separate into two equations for the electric field (see electrost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transient Magnetic Field
Transience or transient may refer to: Music * ''Transient'' (album), a 2004 album by Gaelle * ''Transience'' (Steven Wilson album), 2015 * Transience (Wreckless Eric album) Science and engineering * Transient state, when a process variable or variables have been changed and the system has not yet reached a steady state. * Transient modelling, a way of looking at a process with the primary criterion of time, observing the pattern of changes in the subject being studied over time. * Transient response, the response of a system to a change from an equilibrium or a steady state. * Transient (acoustics), a high-amplitude, short-duration sound at the beginning of a waveform * Transient (astronomy), an astronomical object or phenomenon of short duration * Transient (civil engineering), any pressure wave that is short lived * Transient (computer programming), a property of any element in the system that is temporary * Transient (oscillation), a short-lived burst of energy caused by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KTH Royal Institute Of Technology
KTH Royal Institute of Technology (), abbreviated KTH, is a Public university, public research university in Stockholm, Sweden. KTH conducts research and education in Institute of technology, engineering and technology and is Sweden's largest technical university. Since 2018, KTH consists of five #Schools, schools with four #Campuses, campuses in and around Stockholm. KTH was established in 1827 as the ''Teknologiska institutet'' (Institute of Technology) and had its roots in the ''Mekaniska skolan'' (School of Mechanics) that was established in 1798 in Stockholm. But the origin of KTH dates back to the predecessor of the ''Mekaniska skolan'', the ''Laboratorium mechanicum'', which was established in 1697 by the Swedish scientist and innovator Christopher Polhem. The ''Laboratorium mechanicum'' combined education technology, a laboratory, and an exhibition space for innovations. In 1877, KTH received its current name, ''Kungliga Tekniska högskolan'' (KTH Royal Institute of Techn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
