Technology and the built world

Defense Meteorological Satellite Program

The Defense Meteorological Satellite Program (DMSP) is a United States military series of polar-orbiting weather satellites that has supported Department of Defense operations since 1962.

Defense Security Cooperation Agency

The Defense Security Cooperation Agency (DSCA) is a U.S. Department of Defense agency that administers Foreign Military Sales and builds the capacity of foreign security forces.

Defense Support Program

The Defense Support Program is an American satellite constellation using infrared sensors in geosynchronous orbit to give early warning of ballistic missile launches, first launched in 1970.

Defense Threat Reduction Agency

The Defense Threat Reduction Agency (DTRA) is a US Department of Defense agency, established in 1998 to counter weapons of mass destruction, and runs the Nunn-Lugar Cooperative Threat Reduction program.

Defensive driving

Defensive driving, also called safe driving, is a style of driving that uses anticipation and space management to prevent collisions despite other drivers' actions or adverse conditions.

Defensive fighting position

A defensive fighting position, also called a fighting pit or machine gun nest, is an excavated place from which soldiers engage an enemy under cover.

Defensive programming

Defensive programming is a software development practice in which code anticipates and handles faulty conditions like invalid input and hardware faults, pioneered by Margaret Hamilton for the Apollo flight software.

Defensive wall

A defensive wall, also known as a city wall, is a barrier of earth, brick, or stone built to protect settlements or frontiers, ranging from city circuits to frontiers hundreds of kilometers long.

Deficit round robin

Deficit round robin (DRR) is a network scheduling algorithm, invented by M. Shreedhar and George Varghese in 1995, that fairly queues variable-length packets in constant time.

Definition of done

The definition of done, or DoD, is a Scrum practice: a shared checklist of quality requirements, such as testing and code review, that work must satisfy to count as finished.

Deflagration

Deflagration is the propagation of a combustion zone through a reactive material at subsonic speed, driven by heat transfer rather than a shock wave, as in gunpowder and gas flames.

Deflagration-to-detonation transition

The deflagration-to-detonation transition (DDT) is the process by which a subsonic combustion wave, a deflagration, accelerates and reorganizes into a supersonic detonation, seen in pulse detonation engines and vapor cloud explosions.

Deflectometry

Deflectometry is an optical metrology technique that measures the local slope of specular surfaces from the reflection of a displayed pattern, reconstructing surface height and detecting micrometer-deep defects.

Deformable convolution

Deformable convolution is a neural network operator whose kernel sampling locations shift by learned offsets, letting the grid adapt to object shapes. Introduced at ICCV 2017.

Deformable model (computer vision)

A deformable model in computer vision is a curve or surface pulled by image forces onto object boundaries, best known as the snake, or active contour.

Deformable object manipulation

Deformable object manipulation (DOM) is the branch of robotics in which robots grasp, move, and reshape objects like cables, clothes, food, and surgical tissue, applied in manufacturing, logistics, and surgery.

Deformation mapping

Deformation mapping is the time-dependent function in continuum mechanics that carries each material point of a body from its reference configuration to its deformed configuration under load.

Deformation monitoring

Deformation monitoring is the repeated measurement of changes in the position, shape, or movement of structures, terrain, or landslides over time, using geodetic surveys, geotechnical instruments, and remote sensing.

Defragmentation

Defragmentation, also called defragging or disk defragmentation, moves portions of files so each file's clusters are stored contiguously, improving access speed on hard drives; Windows runs it as a scheduled weekly task.

Defunctionalization

Defunctionalization is a whole-program transformation, devised by John Reynolds in 1972, that removes first-class functions by replacing function values with data constructors and an apply function.

Defuzzification

Defuzzification is the final step of a fuzzy inference system, converting a fuzzy output set into one crisp number that an actuator or decision procedure can use.

Defy Media

Defy Media, LLC was an American digital media company formed in 2013 by the merger of Alloy Digital and Break Media, owning brands including Smosh and Screen Junkies.

DeGolyer & MacNaughton

DeGolyer & MacNaughton is an independent petroleum consulting firm founded in Dallas, Texas, in 1936 by Everette Lee DeGolyer and Lewis MacNaughton to estimate oil and gas reserves.

Degradation testing

Degradation testing is a reliability engineering method that measures how a product's performance deteriorates over time and predicts failure times, enabling reliability assessment for highly reliable products with few or no observed failures.

Degree of static indeterminacy

The degree of static indeterminacy is the number by which a structure's unknown forces and reactions exceed the equilibrium equations available to solve them; zero means statically determinate.

Degreed, Inc.

Degreed, Inc. is an American enterprise learning technology company founded in 2012 and headquartered in Pleasanton, California, best known for its learning experience platform that aggregates corporate learning content and ties it to skills data.

Degtyaryov machine gun (Пулемёт Дегтярёва)

The Degtyaryov machine gun, also called the DP-27, is a Soviet light machine gun chambered for the 7.62×54mmR cartridge; adopted in 1927, it armed Red Army squads through World War II.

Degumming

Degumming is a treatment of crude fats and oils with water, acid, or enzymes that removes phospholipids and other gum-forming impurities before storage, transport, or further refining.

Degussa P25

Degussa P25, now sold as AEROXIDE TiO₂ P 25 by Evonik, is a titanium dioxide nanopowder of mixed anatase and rutile used as the standard reference photocatalyst.