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FG Sagittae
FG Sagittae (FG Sge) is a star in Sagitta, the central star of the nebula Hen 1-5, observed over a century to change from a hot star to a cool supergiant.
FGOALS (climate model)
FGOALS, the Flexible Global Ocean-Atmosphere-Land System Model, is a coupled climate model from the Chinese Academy of Sciences used in CMIP3 through CMIP6 and IPCC reports.
Fiber Bragg grating
A fiber Bragg grating (FBG) is a periodic refractive index modulation in an optical fiber core that reflects the Bragg wavelength, used in telecommunications and fiber-optic sensing.
Fiber Bragg grating interrogation
Fiber Bragg grating interrogation is the measurement process that tracks the reflected wavelength of a fiber Bragg grating sensor over time and converts shifts into strain or temperature.
Fiber bundle
A fiber bundle is a map between topological spaces that locally looks like a product, describing how a fiber space attaches to a base space.
Fiber coupler
A fiber coupler is a passive optical device that splits, combines, or redirects optical power between fiber ports without electronic conversion, used throughout fiber-optic networks.
Fiber diffraction
Fiber diffraction is an X-ray technique that determines the structure of fibrous or polymeric molecules from oriented bundles, famously yielding the DNA double helix and the α-helix.
Fiber laser
A fiber laser is a laser whose gain medium is optical fiber doped with rare-earth ions, typically ytterbium, first demonstrated by Elias Snitzer in 1961 and now widely used for cutting and welding metals.
Fiber optical cavity
A fiber optical cavity is a light resonator built inside optical fiber, using mirrors such as fiber Bragg gratings, coatings, or loops instead of bulk optics.
Fiber product of schemes
The fiber product of schemes X ×S Y is the categorical pullback of two morphisms to a common base S, underlying intersections, fibers, and base change.
Fiber waveguide theory
Fiber waveguide theory is the body of electromagnetics describing how light propagates as guided modes in optical fibers, with the LP mode description as its central result.
Fiber-laser-driven attosecond source
A fiber-laser-driven attosecond source is a tabletop setup in which an ultrafast fiber laser drives high-order harmonic generation to produce attosecond pulses, offering higher repetition rates than Ti:sapphire.
Fiber-optic cable
A fiber-optic cable, also called an optical fiber cable, is a protective assembly containing glass fibers that guide light by total internal reflection to carry information.
Fiber-optic gyroscope
A fiber-optic gyroscope (FOG) is a solid-state rotation sensor that measures angular velocity using the Sagnac effect, with no moving parts, used in inertial navigation systems.
Fiber-optic sensor
A fiber-optic sensor is a device that uses light guided in an optical fiber to measure temperature, strain, or pressure, immune to electromagnetic interference in harsh environments.
Fiberglass
Fiberglass, also called glass fiber or glass reinforced plastic, is a material of extremely fine glass strands used to reinforce plastics and, as glass wool, to insulate buildings.
Fiberscope
A fiberscope, also called a snake camera, is a flexible endoscope that transmits images from its tip through a bundle of optical fibers for inspecting cavities.
Fibonacci
Fibonacci, also known as Leonardo Pisano or Leonardo of Pisa (c. 1170–c. 1250), was an Italian mathematician who introduced Hindu-Arabic numerals to Europe in his 1202 Liber Abaci.
Fibonacci anyon
A Fibonacci anyon is a non-Abelian quasiparticle whose fusion rule τ × τ = 1 + τ gives Fibonacci-number fusion paths, the simplest model universal for quantum computation by braiding alone.
Fibonacci coding
Fibonacci coding, also called the Gopala-Hemachandra code, is a universal, prefix-free code for positive integers that uses the Zeckendorf representation and ends each codeword with the pair 11.
Fibonacci cube
The Fibonacci cube is a graph whose vertices are binary strings with no two consecutive 1s, introduced by Wen-Ping Hsu in 1993 as an interconnection network topology.
Fibonacci sequence
The Fibonacci sequence, also known as the Fibonacci series, is the integer sequence 0, 1, 1, 2, 3, 5, 8, 13, in which each term is the sum of the two before it.
Fibonacci word
The Fibonacci word, also called the rabbit sequence, is an infinite binary sequence beginning 0100101001001, the fixed point of the substitution sending 0 to 01 and 1 to 0.
Fibration
A fibration is a continuous map between topological spaces with the homotopy lifting property; Serre fibrations, introduced in 1951, organize homotopy theory and yield long exact sequences of homotopy groups.
Fibrous red phosphorus
Fibrous red phosphorus, also called fibrous phosphorus, is a crystalline allotrope of phosphorus in which parallel pentagonal phosphorus tubes give it strongly anisotropic properties, investigated for lithium-ion batteries.
Fick's laws of diffusion
Fick's laws of diffusion, also called Fickian diffusion, are two equations published by Adolf Fick in 1855 that describe how a substance flows down a concentration gradient.
Fictitious domain method
The fictitious domain method is a numerical technique for solving partial differential equations on irregular or moving domains by embedding them in a larger, simply shaped one.
Fictitious force
A fictitious force, also called a pseudo force or inertial force, is an apparent force introduced in accelerating reference frames so Newton's laws can be used there.
Fictitious play
Fictitious play is an iterative game-theory process in which each player best-responds to opponents' past play frequencies, used to model learning and compute Nash equilibria.
Fidelity (quantum mechanics)
Fidelity in quantum mechanics measures how similar two quantum states are, from 0 to 1, and is used to benchmark teleportation, quantum gates, and prepared states.