42,772 articles
Quality control
Quality control (QC), also known as total quality control, is the set of operational techniques, such as inspection, testing, and statistical monitoring, used to fulfill quality requirements.
Quality function deployment
Quality function deployment, also known as customer-driven engineering, is a structured method translating customer needs into technical requirements, developed in Japan in the late 1960s.
Quality management
Quality management is the coordinated set of organizational activities used to plan, control, assure, and improve product quality, combining statistical process control, continual improvement, and standards like ISO 9001.
Quality of life
Quality of life (QoL) is a person's own perception of their position in life, covering health, psychology, independence, and relationships, by the World Health Organization's definition.
Quan Li
Quan Li (李全) is a materials scientist at Kent State University's Liquid Crystal Institute since 2004, known for his 2016 Nature paper controlling chiral liquid crystals with light alone.
Quandle
A quandle is an algebraic structure, introduced into knot theory independently by David Joyce and Sergei Matveev in 1982, whose axioms capture conjugation in a group.
Quantal neurotransmitter release
Quantal neurotransmitter release is the discharge of neurotransmitter in discrete packets, each the contents of one synaptic vesicle, proposed by Bernard Katz and José del Castillo in 1954.
Quantale
A quantale is a complete lattice equipped with an associative binary operation distributing over arbitrary joins in each variable, introduced by C. J. Mulvey to extend locales non-commutatively for quantum logic.
Quantified modal logic
Quantified modal logic (QML) combines a propositional modal logic with first-order quantifiers; the Barcan Formula is valid under constant domains but fails under the varying domains Kripke introduced in 1963.
Quantifier (logic)
A quantifier, also called a logical quantifier, is an operator in predicate logic, such as "for all" or "there exists", expressing how many objects satisfy a formula.
Quantifier elimination
Quantifier elimination is a property of first-order theories in model theory: every formula is equivalent, over the theory, to one with no quantifiers, which can yield decidability.
Quantile
A quantile is a value below which a specified fraction of a probability distribution or data sample falls; the median is the 0.5 quantile, and quartiles, deciles, and percentiles are other named cases.
Quantile function
The quantile function of a random variable, also called the inverse cumulative distribution function, maps a probability p to the smallest value x where the CDF reaches p, the basis of inverse transform sampling.
Quantile mapping
Quantile mapping is a statistical bias correction method that adjusts model or sensor data so its quantiles match an observed reference distribution, widely used in hydrologic modeling.
Quantitative content analysis
Quantitative content analysis is a social science research method that assigns communication content to categories by explicit rules, then uses statistics to describe messages and infer about their context.
Quantitative descriptive analysis
Quantitative descriptive analysis (QDA) is a sensory evaluation method in which a small trained panel, typically 10 to 12 subjects, rates the intensity of product attributes on line scales.
Quantitative microscopy
Quantitative microscopy is the family of microscopy techniques that extract numerical measurements of structure, composition, and properties from images, using stereology and image analysis on light and electron micrographs.
Quantitative nanomechanical mapping
Quantitative nanomechanical mapping is an atomic force microscopy technique that maps mechanical properties such as elastic modulus and adhesion by fitting a force-distance curve at every image pixel.
Quantitative NMR
Quantitative NMR (qNMR) is the use of nuclear magnetic resonance spectroscopy to measure concentrations, purities, or composition ratios, used in pharmaceutical analysis, metabolomics, and forensics.
Quantitative oblique back-illumination microscopy
Quantitative oblique back-illumination microscopy (qOBM) is a label-free microscopy technique that measures quantitative phase and refractive index in thick, scattering samples using a bright-field microscope.
Quantitative phase imaging
Quantitative phase imaging is a label-free microscopy technique that measures the phase shift of light through transparent specimens, quantifying thickness, refractive index, and dry mass.
Quantitative phase microscopy
Quantitative phase microscopy (QPM) is a label-free microscopy family that measures light's phase delay through transparent specimens to quantify refractive index, thickness, and dry mass.
Quantitative precipitation estimation
Quantitative precipitation estimation (QPE) converts radar, gauge, and satellite observations into precipitation rates and accumulations used in flash flood warning, hydrologic modeling, and data assimilation.
Quantitative precipitation forecast
A quantitative precipitation forecast (QPF) is a forecast of expected rainfall or snowfall, expressed as liquid water depth, over an area during a specific time window.
Quantitative research
Quantitative research collects data in numerical form, such as scores, counts, and ratings, and analyzes it with statistical models using techniques like experiments and surveys.
Quantitative structure–activity relationship
A quantitative structure–activity relationship (QSAR), also called a quantitative structure–property relationship, is a mathematical model that predicts a chemical's biological or physicochemical activity from its molecular structure, used widely in drug discovery and regulatory chemistry.
Quantity
A quantity is an attribute of a phenomenon, body, or substance that can be determined quantitatively, such as length, mass, or electric charge, with values expressed as a number and a unit.
Quantization (physics)
Quantization in physics is the procedure converting a classical system into a quantum system, and the related fact that energy, charge, and angular momentum take only discrete values.
Quantization (signal processing)
Quantization in signal processing, also called signal quantization, maps a continuous range of amplitudes onto discrete levels; an n-bit converter provides 2^n levels, and the resulting approximation is the source of quantization error and noise.
Quantized enveloping algebra
A quantized enveloping algebra is a one-parameter Hopf algebra deformation of the universal enveloping algebra of a semisimple Lie algebra, introduced by Drinfeld and Jimbo around 1985.