CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search In mathematical logic , the Peano axioms , also known as the Dedekind–Peano axioms or the Peano postulates , are a set of axioms for the natural numbers presented by the 19th century Italian mathematician Giuseppe Peano . These axioms have been used nearly unchanged in a number of metamathematical investigations, including research into fundamental questions of consistency and completeness of number theory . The need for formalism in arithmetic was not well appreciated until the work of Hermann Grassmann , who showed in the 1860s that many facts in arithmetic could be derived from more basic facts about the successor operation and induction . [ 1 ] In 1881, Charles Sanders Peirce provided an axiomatization of natural-number arithmetic. [ 2 ] In 1888, Richard Dedekind proposed a collection...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search A wavelet is a wave -like oscillation with an amplitude that begins at zero, increases, and then decreases back to zero. It can typically be visualized as a "brief oscillation" like one might see recorded by a seismograph or heart monitor . Generally, wavelets are purposefully crafted to have specific properties that make them useful for signal processing . Wavelets can be combined, using a "reverse, shift, multiply and integrate" technique called convolution , with portions of a known signal to extract information from the unknown signal. Seismic wavelet For example, a wavelet could be created to have a frequency of Middle C and a short duration of roughly a 32nd note . If this wavelet was to be convolved with a signal created from the recording of a song, then the resulting signal w...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For other uses, see Albedo (disambiguation) . Percentage of diffusely reflected sunlight in relation to various surface conditions Albedo ( / æ l ˈ b iː d oʊ / ), or reflection coefficient , derived from Latin albedo "whiteness" (or reflected sunlight) in turn from albus "white", is the diffuse reflectivity or reflecting power of a surface. It is the ratio of reflected radiation from the surface to incident radiation upon it. Its dimensionless nature lets it be expressed as a percentage and is measured on a scale from zero for no reflection of a perfectly black surface to 1 for perfect reflection of a white surface. Albedo depends on the frequency of the radiation. When quoted unqualified, it usually refers to some appropriate average across the spectrum of visible light . In gener...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For other uses of the terms Q , Q factor , and Quality factor , see Q value (disambiguation) . The bandwidth , , or f 1 to f 2 , of a damped oscillator is shown on a graph of energy versus frequency. The Q factor of the damped oscillator, or filter, is . The higher the Q, the narrower and 'sharper' the peak is. In physics and engineering the quality factor or Q factor is a dimensionless parameter that describes how under-damped an oscillator or resonator is, [ 1 ] as well as characterizes a resonator's bandwidth relative to its center frequency. [ 2 ] Higher Q indicates a lower rate of energy loss relative to the stored energy of the resonator; the oscillations die out more slowly. A pendulum suspended from a high-quality bearing, oscillating in air, has a high Q , while a pendulum im...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For other uses of the terms Q , Q factor , and Quality factor , see Q value (disambiguation) . The bandwidth , , or f 1 to f 2 , of a damped oscillator is shown on a graph of energy versus frequency. The Q factor of the damped oscillator, or filter, is . The higher the Q, the narrower and 'sharper' the peak is. In physics and engineering the quality factor or Q factor is a dimensionless parameter that describes how under-damped an oscillator or resonator is, [ 1 ] as well as characterizes a resonator's bandwidth relative to its center frequency. [ 2 ] Higher Q indicates a lower rate of energy loss relative to the stored energy of the resonator; the oscillations die out more slowly. A pendulum suspended from a high-quality bearing, oscillating in air, has a high Q , while a pendulum im...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search Figure 1. The light path through a Michelson interferometer . The two light rays with a common source combine at the half-silvered mirror to reach the detector. They may either interfere constructively (strengthening in intensity) if their light waves arrive in phase, or interfere destructively (weakening in intensity) if they arrive out of phase, depending on the exact distances between the three mirrors. Interferometry is a family of techniques in which waves, usually electromagnetic , are superimposed in order to extract information about the waves. [ 1 ] Interferometry is an important investigative technique in the fields of astronomy , fiber optics , engineering metrology , optical metrology, oceanography , seismology , spectroscopy (and its applications to chemistry ), quantum m...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search In Unix and related computers operating systems, a file descriptor ( FD , less frequently fildes ) is an abstract indicator used to access a file or other input/output resource, such as a pipe or network connection. File descriptors are part of the POSIX application programming interface . A file descriptor is a non-negative integer , represented in C programming language as the type int . It typically serves as an index into a table maintained by the kernel that tracks which files are "opened" by a process for performing input/output. There are three standard POSIX file descriptors, corresponding to the three standard streams , which presumably every process (save perhaps a daemon ) should expect to have: Integer value Name <unistd.h> symbolic constant [ 1 ] <stdio.h> file stream [ ...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For the Black Eyed Peas song, see The Time (Dirty Bit) . A dirty bit or modified bit is a bit that is associated with a block of computer memory and indicates whether or not the corresponding block of memory has been modified. [ 1 ] The dirty bit is set when the processor writes to (modifies) this memory. The bit indicates that its associated block of memory has been modified and has not yet been saved to storage . When a block of memory is to be replaced, its corresponding dirty bit is checked to see if the block needs to be written back to secondary memory before being replaced or if it can simply be removed. Dirty bits are used by the CPU cache and in the page replacement algorithms of an operating system . Dirty bits can also be used in Incremental computing by marking segments of data...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search The Lunar Laser Ranging Experiment from the Apollo 11 mission. The ongoing Lunar Laser Ranging Experiment measures the distance between the Earth and the Moon using laser ranging . Lasers on Earth are aimed at retroreflectors planted on the Moon during the Apollo program (11, 14, and 15), and the time for the reflected light to return is determined. Apollo 15 LRRR Apollo 15 LRRR schematic The first successful tests were carried out in 1962 when a team from the Massachusetts Institute of Technology succeeded in observing laser pulses reflected from moon's surface using a laser with a millisecond pulse length. Similar measurements were obtained later the same year by a Soviet team at the Crimean Astrophysical Observatory using a Q-switched ruby laser . [ 1 ] Greater accurac...

CentralNotice From Wikipedia, the free encyclopedia (Redirected from EME (communications) ) Jump to: navigation , search Earth–Moon–Earth communication (EME) , also known as moon bounce , is a radio communications technique which relies on the propagation of radio waves from an Earth -based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver. 1 History 2 EME communications technical details 3 Echo delay and time spread 4 Current EME communications 5 Modulation types and frequencies optimal for EME 6 Other factors influencing EME communications 6.1 Gallery 7 See also 8 References 9 External links History [ edit ] The use of the Moon as a passive communications satellite was proposed by W.J. Bray of the British General Post Office in 1940. It was calculated that with the available microwave transmission pow...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. (May 2009) Sierpinski triangle Generated using a random algorithm Sierpinski triangle in logic: The first 16 conjunctions of lexicographically ordered arguments The columns interpreted as binary numbers give 1, 3, 5, 15, 17, 51... (sequence A001317 in OEIS ) The Sierpinski triangle (also with the original orthography Sierpiński ), also called the Sierpinski gasket or the Sierpinski Sieve , is a fractal and attractive fixed set with the overall shape of an equilateral triangle, subdivided recursively into smaller equilateral triangles. Originally constructed as a curve, this is one of ...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search In mathematics , specifically in ring theory , an algebra over a commutative ring is a generalization of the concept of an algebra over a field , where the base field K is replaced by a commutative ring R . In this article, all rings are assumed to be unital . 1 Formal definition 2 Example 2.1 Split-biquaternions 3 Associative algebras 4 Non-associative algebras 5 See also 6 References 7 Further reading Formal definition [ edit ] Let R be a commutative ring. An R -algebra is an R -module A together with a binary operation [·, ·] called A - multiplication , which satisfies the following axiom: Bilinearity : for all scalars , in R and all elements x , y , z in A . Example [ edit ] Split-biquaternions [ edit ] The split-biquaternions are an example of a...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search This article includes a list of references , related reading or external links , but its sources remain unclear because it lacks inline citations . Please improve this article by introducing more precise citations. (March 2013) In mathematics , the Cayley–Dickson construction , named after Arthur Cayley and Leonard Eugene Dickson , produces a sequence of algebras over the field of real numbers , each with twice the dimension of the previous one. The algebras produced by this process are known as Cayley–Dickson algebras . They are useful composition algebras frequently applied in mathematical physics . The Cayley–Dickson construction defines a new algebra based on the direct sum of an algebra with itself, with multiplication defined in a specific way and an involution known as conju...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For numbers "constructible" in the sense of set theory , see Constructible universe . For example, the square root of 2 is constructible : from the length unit, we can construct a line segment of length with straightedge and compass. A point in the Euclidean plane is a constructible point if, given a fixed coordinate system (or a fixed line segment of unit length ), the point can be constructed with unruled straightedge and compass . A complex number is a constructible number if its corresponding point in the Euclidean plane is constructible from the usual x - and y -coordinate axes. It can then be shown that a real number r is constructible if and only if , given a line segment of unit length, a line segment of length | r | can be constructed with compass and straightedge. [ 1 ] It...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search Not to be confused with Hyperbolic paraboloid . Hyperboloid of one sheet Common conical surface Hyperboloid of two sheets In mathematics , a hyperboloid is a quadric – a type of surface in three dimensions – described by the equation (hyperboloid of one sheet), or (hyperboloid of two sheets). Both of these surfaces asymptote to the same conical surface as x or y become large: These are also called elliptical hyperboloids. If and only if a = b , it is a hyperboloid of revolution, and is also called a circular hyperboloid. 1 Cartesian coordinates 2 Generalised equations 3 Properties 4 In more than three dimensions 5 Hyperboloid structures 6 Relation to the sphere 7 See also 8 References 9 External links Cartesian coordinates [ edit ] Animation of a hyp...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search The Chinese remainder theorem was proved by Gauss with his 1801 book Disquisitiones Arithmeticae . [ 1 ] The Chinese remainder theorem is a result about congruences in number theory and its generalizations in abstract algebra . It was first published in the 3rd to 5th centuries by the Chinese mathematician Sun Tzu . In its basic form, the Chinese remainder theorem will determine a number n that, when divided by some given divisors, leaves given remainders. For example, what is the lowest number n that when divided by 3 leaves a remainder of 2, when divided by 5 leaves a remainder of 3, and when divided by 7 leaves a remainder of 2? 1 Theorem statement 2 Existence and uniqueness 2.1 Case of two equations ( k = 2 ) 2.2 General case 3 Finding the solution with basic algebra ...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search United States National Security Council Agency overview Formed September 18, 1947 Agency executives Barack Obama , President of the United States , Chairman Joe Biden , Vice President of the United States John Kerry , Secretary of State Ashton Carter , Secretary of Defense Susan Rice , National Security Advisor Parent agency Executive Office of the President of the United States Website NSC Website President Barack Obama at a NSC Meeting in the Situation Room. Participants include Secretary of State Hillary Rodham Clinton, Defense Secretary Robert Gates, NSC Advisor Gen. James "Jim" Jones, Director of National Intelligence(DNI) Dennis Blair, Deputy National Security Adviser Tom Donilon, White House Counsel Greg Craig, CIA Director Leon Panetta, Vice Chairman o...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search RLX Technologies Industry Computer hardware , Computer software, Computer systems Fate acquired by HP in 2005 Founded 1999 Founders Christopher Hipp , Headquarters The Woodlands , Unincorporated Montgomery County , Texas , United States Area served United States Key people Christopher Hipp , Founder, former President and CEO Doug Erwin , Last Chief Executive Officer Products Blade Servers , Server Management Software RLX Technologies (bought by HP in 2005) was a company based in The Woodlands, TX and was the first company in the world to create and market what is now known as a blade server . Founded in 1999 by Christopher Hipp , one of the inventors of the blade server, and numerous former Compaq Computers employees, the company pioneered the use ...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search This article is about the specific type of noun classes. For uses of language associated with men and women, see Language and gender . For methods of minimizing the use of gendered forms, see Gender-neutral language . For other uses, see Gender (disambiguation) . This article possibly contains original research . Please improve it by verifying the claims made and adding inline citations . Statements consisting only of original research should be removed. (August 2013) Diagrams roughly representing the noun distribution in some languages. The examples include: 1. masculine – feminine 2. masculine – feminine – neuter 3. animate – inanimate Note: The example words given do not necessarily belong to the indicated genders in the languages mentioned. Also, the sets are not necessar...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. (October 2014) The logo used by the Heaven's Gate group Heaven's Gate was an American UFO religious Millenarian group based in San Diego, California , founded in the early 1970s and led by Marshall Applewhite (1931–1997) and Bonnie Nettles (1927–1985). [ 1 ] On March 26, 1997, police discovered the bodies of 39 members of the group who had committed mass suicide [ 2 ] in order to reach what they believed was an alien space craft following Comet Hale–Bopp . [ 3 ] 1 History 2 Belief system 3 Structure 4 Mass suicide and aftermath 5 Media coverage prior to suicide 6 See also 7 Referenc...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search "APL programming language family" redirects here. For programming languages that were influenced by APL, see Category:APL programming language family . APL Paradigm array , functional , structured , modular Designed by Kenneth E. Iverson Developer Kenneth E. Iverson First appeared 1964 Typing discipline dynamic Major implementations Dyalog APL , IBM APL2 , APL2000 , Sharp APL, APLX , NARS2000 , GNU APL [ 1 ] Dialects A+ , Dyalog APL, APLNext, ELI , J Influenced by mathematical notation Influenced J , [ 2 ] K , [ 3 ] Mathematica , MATLAB , [ 4 ] Nial , [ 5 ] PPL , Q , S This article contains APL source code . Without proper rendering support , you may see question marks, boxes, or other symbols instead of APL symbols . Prom...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For other uses, see Digraph (disambiguation) and Trigraph (disambiguation) . This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. (September 2008) In computer programming , digraphs and trigraphs are sequences of two and three characters respectively, appearing in source code , which a programming language specification requires an implementation of that language to treat as if they were one other character. Various reasons exist for using digraphs and trigraphs: keyboards may not have keys to cover the entire character set of the language, input of special characters may be difficult, text editors may reserve some characters for special use and so on....

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search Programming paradigms Action Agent-oriented Automata-based Concurrent computing Relativistic programming Data-driven Declarative (contrast: Imperative ) Constraint Dataflow Flow-based Cell-oriented ( spreadsheets ) Reactive Functional Functional logic Logic Abductive logic Answer set Constraint logic Functional logic Inductive logic End-user programming Event-driven Service-oriented Time-driven Expression-oriented Feature-oriented Function-level (contrast: Value-level ) Generic Imperative (contrast: Declarative ) Literate Procedural Language-oriented Natural language programming Discipline-specific Domain-specific Grammar-oriented Dialecting Intentional Metaprogramming Automatic Reflective Attribute-oriented Homoiconic Template Policy-based Non-structured (contras...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. (February 2011) Programming paradigms Action Agent-oriented Automata-based Concurrent computing Relativistic programming Data-driven Declarative (contrast: Imperative ) Constraint Dataflow Flow-based Cell-oriented ( spreadsheets ) Reactive Functional Functional logic Logic Abductive logic Answer set Constraint logic Functional logic Inductive logic End-user programming Event-driven Service-oriented Time-driven Expression-oriented Feature-oriented Function-level (contrast: Value-level ) Generic Imperative (contrast: Declarative ) Literate Procedural Language-oriented Natural language ...

CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search This article may require cleanup to meet Wikipedia's quality standards . The specific problem is: Remove redundancies. Clean up markup. Do something with short sections . Please help improve this article if you can. (September 2013) In linear algebra and functional analysis , the kernel (also null space or nullspace ) of a linear map L : V → W between two vector spaces V and W , is the set of all elements v of V for which L ( v ) = 0 , where 0 denotes the zero vector in W . That is, in set-builder notation , 1 Properties of the Kernel 2 Application to modules 3 The kernel in functional analysis 4 Representation as matrix multiplication 4.1 Subspace properties 4.2 The Row Space of a Matrix 4.3 Left null space 4.4 Nonhomogeneous systems of linear equations 5 Illu...