All articles A–Z
519,064 articles
Structural risk minimization
Structural risk minimization (SRM) is an inductive principle for model selection introduced by Vapnik and Chervonenkis in 1974, balancing empirical error against model capacity to prevent overfitting.
Structural similarity
Structural similarity (SSIM) is an image quality metric that compares luminance, contrast, and structure against a reference image, introduced by Zhou Wang and colleagues in 2004.
Structural similarity index measure
The structural similarity index measure (SSIM) is a full-reference image quality metric, published in 2004, that compares a distorted image against a reference for luminance, contrast, and structure.
Structural steel
Structural steel, also called structural steelwork, is steel shaped into sections, plates, and hollow profiles and used as the load-bearing framework of buildings, bridges, and industrial structures.
Structural topology optimization
Structural topology optimization is a computational design method that distributes material within a design domain to minimize mean compliance for a given amount of material, independent of any starting design.
Structural trap
A structural trap is a hydrocarbon trap where folding, faulting, or upward salt movement stops migrating oil or gas, and it holds most of the world's reserves.
Structural unemployment
Structural unemployment is joblessness that persists because workers' skills, locations, or other characteristics do not match available jobs, and it is generally not remediable by short-term accommodative policy.
Structural variation detection
Structural variation detection is the set of bioinformatics methods that identify large genomic rearrangements of at least 50 bp from sequencing data, using read pairs, split reads, and read depth.
Structural vector autoregression
A structural vector autoregression (SVAR) is an econometric time-series model combining a VAR with identifying restrictions, turning reduced-form residuals into interpretable structural shocks for causal macroeconomic estimates.
Structural violence
Structural violence, coined by Johan Galtung (1969), is harm embedded in social structures producing unequal power and life chances; spans peace studies, public health, and clinical medicine.
Structuralism
Structuralism is a twentieth-century intellectual movement, especially French, that interprets human culture through underlying structural patterns; drawing on Saussure's linguistics, it peaked in the 1960s before post-structuralism displaced it.
Structuralism (psychology)
Structuralism, the first formal school of psychology, named by Edward B. Titchener from Wundt's voluntarism; used introspection to break conscious experience into sensations, images, and affections; declined after Watson's 1913 behaviorist manifesto.
Structure
A structure, in engineering, is an arrangement of connected members such as beams, columns, cables, arches, and trusses that supports loads and transfers them safely to the ground.
Structure (mathematical logic)
In mathematical logic, a structure, also called a model, is a set with relations and functions that interpret a formal language's symbols, making sentences true or false.
Structure and agency
Structure and agency: the central sociological debate on how enduring social patterns relate to individual action, covering Giddens's structuration theory, Archer's morphogenesis, Bourdieu's habitus, and relational alternatives.
Structure and enzymology of complement convertases
Complement convertases are surface-assembled serine-protease holoenzymes, pairing a C3b or C4b scaffold with protease modules Bb or C2a to cleave C3 and C5, amplifying the complement cascade.
Structure and genome of HIV
Structure and genome of HIV: a ~100 nm enveloped retrovirus with a dimeric ~9 kb RNA genome of nine genes (gag, pol, env, tat, rev, vif, vpr, vpu, nef) flanked by LTRs; HIV-2 differs in Vpx/Vpu and 5′-UTR.
Structure clustering (structural biology)
Structure clustering is a computational method that groups related 3D biomolecule structures by geometric similarity, producing clusters with a representative structure, used to organize the protein universe.
Structure factor
The structure factor, or static structure factor, is a complex function giving the amplitude and phase of waves diffracted from a crystal, central to structure analysis by diffraction methods.
Structure from motion
Structure from motion (SfM) is a photogrammetric technique that reconstructs 3D scene geometry and camera positions from overlapping photographs, underpinning low-cost terrain and landform mapping in the earth sciences.
Structure functions
Structure functions, such as F₁ and F₂, are functions of x and Q² that describe the partonic structure of hadrons as measured in deep inelastic scattering.
Structure mapping
Structure mapping is a cognitive psychology theory and method describing analogical reasoning as aligning relational structure between domains while discarding surface features, proposed by Dedre Gentner in 1983.
Structure of globular clusters
The structure of globular clusters is how their stars are distributed in space, described by radial density profiles and parameters such as core radius, tidal radius, and concentration.
Structure of the British Army
Structure of the British Army: organisation from the Sovereign, MOD and Army Headquarters through the Field Army and Home Command to divisions, Brigade Combat Teams, regiments and the Army Reserve, under the 2021 Future Soldier reforms.
Structure of the Canadian federal government
Structure of the Canadian federal government: Canada's Westminster-style constitutional monarchy and parliamentary democracy, with Parliament (Crown, 105-seat Senate, 343-seat House of Commons), a confidence-based Prime Minister and Cabinet, and constitutionally divided federal, provincial, and municipal powers.
Structure of the Pakistan Army
Structure of the Pakistan Army: land force of ~560,000 led from GHQ Rawalpindi by the COAS, organized into nine lieutenant-general-led corps commands, restructured in 2025 under a Chief of Defence Forces.
Structure of the United States Air Force
Structure of the United States Air Force: the USAF's hierarchy from the Secretary of the Air Force and Chief of Staff through major commands, numbered air forces, wings, groups, squadrons, and flights, including the Air National Guard and Reserve and current reorganization.
Structure of the United States Army
The structure of the United States Army, founded in 1775, comprises an active component and two reserve components organized into armies, corps, divisions, and brigades.
Structure of the United States Navy
Structure of the United States Navy: how the Department of the Navy organizes civilian leadership, the shore establishment, and operating forces into administrative and operational chains of command, with nine component commands and seven active numbered fleets under combatant commanders.
Structure set (surgery theory)
In surgery theory, a structure set is the set of manifolds homotopy equivalent to a given space, taken up to a bordism equivalence, and it classifies manifolds.