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QR Ph Logo
QR may refer to: Arts and entertainment * Nippon Cultural Broadcasting (from call sign JOQR), a Tokyo radio station * Queen's Radio, a student radio station at Queen's University Belfast * Quiet Riot, an American rock band Businesses * Qatar Airways (IATA code) * Queensland Rail, a company responsible for the railway system in Queensland, Australia * Quintana Roo (company), a triathlon-specific wetsuit and bicycle company Places * Quintana Roo, a state of Mexico * Karakalpakstan (Qoraqalpog'iston Respublikasi), Uzbekistan (ISO 3166-2 subcode UZ-QR) Science and technology * QR code (Quick Response code), a two-dimensional code * ATCvet code QR ''Respiratory system'', a section of the Anatomical Therapeutic Chemical Classification System for veterinary medicinal products * DICOM Q/R, DICOM Query / Retrieve * Nissan QR engine * Quarter (unit) ** qr., , of a yard, equal to 9 inches ** qr. av., , of a hundredweight, equal to 2 stone or 28 pounds avoirdupois Mathematics * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queensrÿche
Queensrÿche () is an American progressive metal band. It formed in 1982 in Bellevue, Washington, out of the local band the Mob. The band has released 16 studio albums, one Extended play, EP, and several DVDs, and continues to tour and record. The original lineup consisted of guitarists Michael Wilton and Chris DeGarmo, drummer Scott Rockenfield, bassist Eddie Jackson (musician), Eddie Jackson, and lead vocalist Geoff Tate. Queensrÿche has sold more than 20 million albums worldwide, including more than six million albums in the United States. A leader of the progressive metal scene of the mid-to-late 1980s, the band is often referred to as one of the genre's "Big Three", along with Dream Theater and Fates Warning. The band received worldwide acclaim for their 1988 album ''Operation: Mindcrime'', widely considered among the greatest heavy metal music, heavy metal concept albums. Their next album, ''Empire (Queensrÿche album), Empire'' (1990), was also very successful and incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quarterly Review
The ''Quarterly Review'' was a literary and political periodical founded in March 1809 by London publishing house John Murray. It ceased publication in 1967. It was referred to as ''The London Quarterly Review'', as reprinted by Leonard Scott, for an American edition. Early years Initially, the ''Quarterly'' was set up primarily to counter the influence on public opinion of the ''Edinburgh Review''. Its first editor, William Gifford, was appointed by George Canning, at the time Foreign Secretary, later Prime Minister. Early contributors included Secretaries of the Admiralty John Wilson Croker and Sir John Barrow, Poet Laureate Robert Southey, poet-novelist Sir Walter Scott, Italian exile Ugo Foscolo, Gothic novelist Charles Robert Maturin, and the essayist Charles Lamb. Under Gifford, the journal took the Canningite liberal-conservative position on matters of domestic and foreign policy, if only inconsistently. It opposed major political reforms, but it supported the gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Quotient
In chemical thermodynamics, the reaction quotient (''Q''r or just ''Q'') is a dimensionless quantity that provides a measurement of the relative amounts of products and reactants present in a reaction mixture for a reaction with well-defined overall stoichiometry at a particular point in time. Mathematically, it is defined as the ratio of the activity (chemistry), activities (or Molar mass, molar concentrations) of the product species over those of the reactant species involved in the chemical reaction, taking stoichiometric coefficients of the reaction into account as exponents of the concentrations. In equilibrium, the reaction quotient is constant over time and is equal to the equilibrium constant. A general chemical reaction in which ''α'' mole (chemistry), moles of a reactant A and ''β'' moles of a reactant B react to give ''ρ'' moles of a product R and ''σ'' moles of a product S can be written as :\it \alpha\,\rm A + \it \beta\,\rm B \it \rho\,\rm R + \it \sigma\,\rm S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasireversibility
In queueing theory, a discipline within the mathematical theory of probability, quasireversibility (sometimes QR) is a property of some queues. The concept was first identified by Richard R. Muntz and further developed by Frank Kelly. Quasireversibility differs from reversibility in that a stronger condition is imposed on arrival rates and a weaker condition is applied on probability fluxes. For example, an M/M/1 queue with state-dependent arrival rates and state-dependent service times is reversible, but not quasireversible. A network of queues, such that each individual queue when considered in isolation is quasireversible, always has a product form stationary distribution. Quasireversibility had been conjectured to be a necessary condition for a product form solution in a queueing network, but this was shown not to be the case. Chao et al. exhibited a product form network where quasireversibility was not satisfied. Definition A queue with stationary distribution \pi is quasire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadratic Reciprocity
In number theory, the law of quadratic reciprocity is a theorem about modular arithmetic that gives conditions for the solvability of quadratic equations modulo prime numbers. Due to its subtlety, it has many formulations, but the most standard statement is: This law, together with its supplements, allows the easy calculation of any Legendre symbol, making it possible to determine whether there is an integer solution for any quadratic equation of the form x^2\equiv a \bmod p for an odd prime p; that is, to determine the "perfect squares" modulo p. However, this is a non-constructive result: it gives no help at all for finding a ''specific'' solution; for this, other methods are required. For example, in the case p\equiv 3 \bmod 4 using Euler's criterion one can give an explicit formula for the "square roots" modulo p of a quadratic residue a, namely, :\pm a^ indeed, :\left (\pm a^ \right )^2=a^=a\cdot a^\equiv a\left(\frac\right)=a \bmod p. This formula only works if it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QR Algorithm
In numerical linear algebra, the QR algorithm or QR iteration is an eigenvalue algorithm: that is, a procedure to calculate the eigenvalues and eigenvectors of a Matrix (mathematics), matrix. The QR algorithm was developed in the late 1950s by John G. F. Francis and by Vera N. Kublanovskaya, working independently. The basic idea is to perform a QR decomposition, writing the matrix as a product of an orthogonal matrix and an upper triangular matrix, multiply the factors in the reverse order, and iterate. The practical QR algorithm Formally, let be a real matrix of which we want to compute the eigenvalues, and let . At the -th step (starting with ), we compute the QR decomposition where is an orthogonal matrix (i.e., ) and is an upper triangular matrix. We then form . Note that A_ = R_k Q_k = Q_k^ Q_k R_k Q_k = Q_k^ A_k Q_k = Q_k^ A_k Q_k, so all the are Similar matrix, similar and hence they have the same eigenvalues. The algorithm is numerical stability, numerically stable b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QR Decomposition
In linear algebra, a QR decomposition, also known as a QR factorization or QU factorization, is a decomposition of a matrix ''A'' into a product ''A'' = ''QR'' of an orthonormal matrix ''Q'' and an upper triangular matrix ''R''. QR decomposition is often used to solve the linear least squares (LLS) problem and is the basis for a particular eigenvalue algorithm, the QR algorithm. Cases and definitions Square matrix Any real square matrix ''A'' may be decomposed as : A = QR, where ''Q'' is an orthogonal matrix (its columns are orthogonal unit vectors meaning and ''R'' is an upper triangular matrix (also called right triangular matrix). If ''A'' is invertible, then the factorization is unique if we require the diagonal elements of ''R'' to be positive. If instead ''A'' is a complex square matrix, then there is a decomposition ''A'' = ''QR'' where ''Q'' is a unitary matrix (so the conjugate transpose If ''A'' has ''n'' linearly independent columns, then the first ''n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quarter (unit)
The quarter ( "one-fourth") was used as the name of several distinct English units based on ¼ sizes of some base unit. The "quarter of London" mentioned by ''Magna Carta'' as the national standard measure for wine, ale, and grain was ¼ ton or tun. It continued to be used, e.g. to regulate the prices of bread. This quarter was a unit of 8 bushels of 8 gallons each, understood at the time as a measure of both weight and volume: the grain gallon or half- peck was composed of 76,800 (Tower) grains weight; the ale gallon was composed of the ale filling an equivalent container; and the wine gallon was composed of the wine weighing an equivalent amount to a full gallon of grain. Length In measures of length, the quarter (qr.) was ¼ of a yard, formerly an important measure in the cloth trade. 3 qr. was a Flemish ell, 4 quarters were a yard, 5 qr. was an (English) ell, and 6 qr. was an aune or French ell. Each quarter was made up of 4 nails. Its metric equivalen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nissan QR Engine
The QR family of inline-four piston engines by Nissan were introduced in 2000 and range from in displacement. These motors are aluminum, dual overhead camshaft (DOHC), four-valve designs with variable valve timing and optional direct injection. The engine shares much of its architecture with the YD diesel engine. QR20DE QR20DE The QR20DE produces at 6000 rpm and at 4000 rpm. The bore and stroke is and a compression ratio of 9.9:1. The QR20DE was replaced with the MR20DE engine in most applications in early 2005. Vehicle applications: * 2001-2007 Nissan X-Trail T30, * 2001-2007 Nissan Primera P12 * 2002–present Nissan Serena C24, * 2003-2008 Nissan Teana J31, * 2001-2005 Nissan Wingroad Y11 * 2002-2005 Nissan Avenir W11 * 2001-2004 Nissan Prairie M12 * 2007-2020 Nissan Atlas F24 * 2014-present Nissan Urvan E26 QR20DD The QR20DD is similar to the QR20DE but features NEO direct injection to improve fuel economy and to reduce emissionIt produces at 6 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DICOM
Digital Imaging and Communications in Medicine (DICOM) is a technical standard for the digital storage and Medical image sharing, transmission of medical images and related information. It includes a file format definition, which specifies the structure of a DICOM file, as well as a network communication protocol that uses Internet protocol suite, TCP/IP to communicate between systems. The primary purpose of the standard is to facilitate communication between the software and Computer hardware, hardware entities involved in medical imaging, especially those that are created by different manufacturers. Entities that utilize DICOM files include components of Picture archiving and communication system, picture archiving and communication systems (PACS), such as Modality (medical imaging), imaging machines (modalities), Radiological information system, radiological information systems (RIS), Image scanner, scanners, Printer (computing), printers, Server (computing), computing servers, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
