All articles starting with D
24,034 articles
Differential dynamic microscopy
Differential dynamic microscopy (DDM) is an image-analysis technique that extracts dynamic light scattering data from ordinary microscope images, introduced by Cerbino and Trappe in 2008.
Differential dynamic programming
Differential dynamic programming (DDP) is a second-order trajectory optimization algorithm for nonlinear optimal control, introduced by Jacobson and Mayne in 1970 and widely used for legged robot control.
Differential electrochemical mass spectrometry
Differential electrochemical mass spectrometry (DEMS) is an analytical technique that couples an electrochemical cell to a mass spectrometer to identify volatile electrode products in real time.
Differential equation
A differential equation relates an unknown function to its derivatives, and solving it means finding a function that satisfies the equation; it dates to the late 17th century.
Differential evolution
Differential evolution (DE) is a population-based, gradient-free optimization algorithm introduced by Rainer Storn and Kenneth Price in 1995 and published in 1997, widely used for nonlinear and non-differentiable functions.
Differential form
A differential form, also called an exterior differential form, is a smooth antisymmetric tensor field on a differentiable manifold, the natural object for integration and for writing Maxwell's equations.
Differential Galois theory
Differential Galois theory, known for linear equations as Picard–Vessiot theory, attaches to each linear differential equation a Galois group capturing algebraic dependencies among solutions and characterizing closed-form solvability.
Differential game
A differential game is a mathematical model in which players with conflicting objectives control a dynamical system evolving continuously in time, extending optimal control theory to multiple agents.
Differential gene expression analysis
Differential gene expression analysis, also called differential expression analysis, is a bioinformatics method comparing gene expression between conditions, typically RNA-seq, to identify significantly up- or down-regulated genes.
Differential geometry
Differential geometry, also known as differential geometry and topology, is the branch of geometry that studies curves and surfaces by analysis, centered on differentiable manifolds and supplying the language of general relativity.
Differential GPS
Differential GPS, also known as DGNSS, is an augmentation technique that improves GPS accuracy to 3 to 5 meters by broadcasting corrections from a surveyed reference station.
Differential hardening
Differential hardening is a heat treatment that makes a blade's edge harder than its body, best known from Japanese swordsmithing, where it produces the hamon temper line.
Differential imaging
Differential imaging is a family of high-contrast astronomical techniques that builds a model of a star's light from reference images and subtracts it, revealing faint exoplanets and disks near the star.
Differential inclusion
A differential inclusion is a continuous-time evolution law x'(t) ∈ F(t, x(t)), generalizing an ordinary differential equation by allowing multiple velocities at each state, with origins in control theory.
Differential interference contrast microscopy
Differential interference contrast (DIC) microscopy is an optical beam-shearing interference technique that converts refractive index gradients in transparent specimens into visible intensity differences, imaging unstained living cells.
Differential interferometric SAR
Differential interferometric SAR (DInSAR) is a radar remote-sensing technique comparing SAR images from repeated satellite passes to measure ground deformation from earthquakes, volcanoes, and subsidence with millimeter precision.
Differential interferometry
Differential interferometry (DInSAR) is a satellite radar remote-sensing method that compares SAR images acquired at different times to measure millimeter-scale ground deformation from earthquakes, volcanoes, landslides, and subsidence.
Differential item functioning
Differential item functioning (DIF) is a psychometric method that flags test items behaving differently for different groups, such as demographic subpopulations, after examinees are matched on ability.
Differential kinematics
Differential kinematics is the branch of robot kinematics describing how joint velocities map to the end effector's instantaneous linear and angular velocities, through the Jacobian matrix.
Differential learning
Differential learning is a motor learning method in which athletes practice a movement in many varied, non-repeated forms without corrective feedback, used in sports training and rehabilitation.
Differential methylation analysis
Differential methylation analysis is a bioinformatics method that compares DNA methylation levels between sample groups, identifying differentially methylated CpG sites and regions in EWAS and cancer studies.
Differential mobility analyzer
A differential mobility analyzer is an aerosol instrument that classifies charged particles by electrical mobility, serving as the central element in systems measuring nanoparticle size distributions.
Differential mobility spectrometry
Differential mobility spectrometry (DMS), also known as FAIMS, is an atmospheric-pressure ion filtering technique used before mass spectrometers, separating ions by how their mobility changes with electric field.
Differential network analysis
Differential network analysis is a bioinformatics method that compares gene or protein interaction networks between conditions, finding rewired interactions rather than changes in single molecules.
Differential of a function
The differential of a function is the main, linear part of its change when the input changes, dy = f′(x) dx; the idea goes back to Leibniz in 1684.
Differential operator
A differential operator, also called a derivative operator, is an operator that maps a function to a function built from its derivatives. The basic example is D = d/dx, whose inverse denotes integration.
Differential optical absorption spectroscopy
Differential optical absorption spectroscopy (DOAS) is a spectroscopic technique that retrieves atmospheric trace-gas concentrations, such as NO2, SO2, and ozone, from UV and visible absorption spectra.
Differential pair
A differential pair is an amplifier stage in which two matched transistors share a single tail current and respond to the difference between their input voltages.
Differential phase contrast imaging
Differential phase contrast (DPC) imaging is an electron microscopy and X-ray technique that maps electric and magnetic fields in materials, reaching atomic resolution in modern instruments.
Differential phase-contrast scanning transmission electron microscopy
Differential phase-contrast scanning transmission electron microscopy (DPC STEM) is an electron microscopy technique that maps electric and magnetic fields inside a specimen by measuring how a focused electron probe is deflected.