42,772 articles
Product (mathematics)
In mathematics, a product is the result of multiplying numbers or algebraic objects, as in 3 × 4 = 12, and extends to constructions like the Cartesian product.
Product distribution
In probability theory, a product distribution is the distribution of the product of two or more random variables, studied with the Mellin transform and applied in reliability, communications, and finance.
Product measure
A product measure is a measure on the Cartesian product of two measure spaces whose value on a measurable rectangle is the product of the factor measures.
Product rule
The product rule, also called the Leibniz product rule, gives the derivative of a product: (fg)' = f'g + fg'. Leibniz first published it without proof in 1684.
Product topology
The product topology, also called the Tychonoff topology, is the standard topology on a Cartesian product of topological spaces, the smallest one making every coordinate projection continuous.
Production part approval process
The production part approval process (PPAP) is an AIAG-defined evidence package by which a supplier demonstrates it can consistently produce parts meeting all design specifications at production rate.
Profile likelihood
The profile likelihood is a function derived from a multi-parameter likelihood by fixing the parameter of interest and maximizing over nuisance parameters, supporting confidence intervals and hypothesis tests.
Profile monitor
A profile monitor is a beam instrumentation device that measures the transverse distribution of particles in an accelerator beam, revealing its size, position, and shape.
Profile monitoring
Profile monitoring is a statistical process control method in which process quality is characterized by the relationship between a response variable and explanatory variables, observed as a curve at each sampling stage.
Profilometry
Profilometry, or surface profilometry, is the quantitative measurement of surface topography, in which an instrument traces or images a surface and records height as a function of position.
Profinite group
A profinite group is a topological group that is an inverse limit of finite groups, or equivalently a compact, totally disconnected group; Galois groups of infinite extensions are examples.
Profinite integer
A profinite integer is an element of the ring of profinite integers, the inverse limit of the residue rings of the integers modulo every positive integer.
Prograde metamorphism
Prograde metamorphism is the recrystallization of a rock toward higher metamorphic grade as pressure, temperature, and fluid pressure rise; its gradual form is called progressive metamorphism.
Program evaluation
Program evaluation is a systematic process of collecting and analyzing data about programs, policies, and organizations to assess their effectiveness and efficiency, using designs such as randomized experiments.
Programmable acoustic metamaterials
Programmable acoustic metamaterials are engineered structures whose acoustic properties can be rewritten in real time by a control system after fabrication. First demonstrated at Duke University in 2015.
Programmable active particles
Programmable active particles are colloidal particles whose 3D shape, surface patches, and propulsion mechanism are engineered in advance so each particle encodes a target motion or assembly.
Programmable matter
Programmable matter is a proposed class of materials whose physical properties, shape, or function can be changed on demand, with computation and actuation embedded throughout the material itself.
Programmable quantum photonic processor
A programmable quantum photonic processor is a reconfigurable integrated optical chip that manipulates quantum states of light, implementing arbitrary unitary transformations by changing control settings rather than hardware.
Programme for International Student Assessment
Programme for International Student Assessment (PISA) is a triennial OECD survey testing 15-year-olds in mathematics, reading, and science since 2000, with results that shape national education policy debates.
Progression-free survival
Progression-free survival (PFS) is a clinical trial endpoint defined as the time from the start of treatment until disease progression or death, whichever comes first.
Progressive enlargement
Progressive enlargement is a construction in stochastic calculus that enlarges a reference filtration so a random time becomes a stopping time, developed from the late 1970s.
Project 8 (neutrino experiment)
Project 8 is a multi-institutional physics experiment aiming to measure the absolute neutrino mass by spectroscopy of tritium beta-decay electrons, using Cyclotron Radiation Emission Spectroscopy (CRES).
Project Azorian
Project Azorian, also known as Project Jennifer, was a secret CIA operation during the Cold War to raise the sunken Soviet submarine K-129, lost with all hands in 1968.
Project Mogul
Project Mogul, also called Operation Mogul, was a top secret US Army Air Forces program from 1947 to 1949 that used high-altitude balloons to detect Soviet atomic tests.
Project Mohole
Project Mohole (1957–1966) was an American scientific program led by the American Miscellaneous Society that attempted to drill through the oceanic crust to the Mohorovičić discontinuity.
Project Phoenix (SETI)
Project Phoenix was a privately funded radio SETI search by the SETI Institute, examining roughly 800 nearby Sun-like stars from 1995 to 2004 with no signals detected.
Project Stormfury
Project Stormfury was a joint US Navy and NOAA program, running from 1962 to 1983, that tried to weaken hurricanes by seeding them with silver iodide.
Project Y
Project Y, also known as the Los Alamos Laboratory, was the Manhattan Project's secret laboratory in Los Alamos, New Mexico, established in 1943 under J. Robert Oppenheimer.
Projected entangled pair states
Projected entangled pair states (PEPS) are tensor-network quantum wave functions built from local tensors on a lattice, generalizing matrix product states to two and more dimensions.
Projectile
A projectile is any object thrown or launched that then moves under gravity alone along a curved path; in the idealized physics model, that path is a parabola.