All articles starting with D

Direct memory access

Direct memory access (DMA) is a transfer strategy in which hardware moves data to or from memory without using the processor, freeing it for other tasks.

Direct metal deposition

Direct metal deposition (DMD) is a laser-based additive manufacturing process that melts powder or wire to build parts layer by layer and repair existing components.

Direct metal laser sintering

Direct metal laser sintering (DMLS) is an additive manufacturing process that uses a laser to fuse thin layers of metal powder into dense parts from CAD data.

Direct method (education)

The direct method is a foreign-language teaching approach, developed in the late nineteenth century against grammar-translation, that uses only the target language; Berlitz schools popularized it.

Direct methods (crystallography)

Direct methods are crystallographic techniques that estimate missing diffraction phases from intensities alone, developed by Karle and Hauptman, who won the 1985 Nobel Prize in Chemistry.

Direct multiple shooting, also called parallel shooting, is an optimal control transcription method that divides the trajectory into segments tied by continuity constraints and solved as one nonlinear program.

Direct normal irradiance

Direct normal irradiance (DNI), also called beam radiation, is the rate at which direct sunlight reaches a surface perpendicular to the Sun's beam, measured in watts per square meter.

Direct nuclear reaction

A direct nuclear reaction is a nuclear reaction in which a projectile interacts with a few surface nucleons in one fast step, without forming a compound nucleus.

Direct numerical simulation

Direct numerical simulation (DNS) is a computational fluid dynamics method that resolves all scales of turbulent flow with no turbulence model, serving mainly as a research tool.

Direct ocean capture

Direct ocean capture (DOC) is a marine carbon removal technology that extracts dissolved CO₂ from seawater using electrochemical processes, letting the treated water absorb more atmospheric CO₂.

Direct part marking

Direct part marking (DPM) physically alters a part's surface to form a machine-readable Data Matrix symbol, using methods such as dot peen, laser marking, or etching.

Direct potable reuse

Direct potable reuse is the introduction of highly treated reclaimed wastewater directly into a drinking water system without an environmental buffer, pioneered in Windhoek, Namibia, in 1968.

Direct preference optimization

Direct preference optimization (DPO) is a method for aligning large language models, introduced by Rafael Rafailov and colleagues in 2023 and used in Llama 3 and Qwen2.

Direct product

The direct product is a construction in algebra that combines structures of the same kind, such as groups or rings, into a single structure with coordinatewise operations.

Direct proof

A direct proof establishes a statement by assuming its hypotheses and deriving the conclusion through an explicit chain of deductions, proving the proposition in its originally stated form rather than a transformed equivalent.

Direct reaction mechanisms

A direct reaction mechanism is a nuclear reaction in which the projectile interacts with the target nucleus in a single, fast step without forming a compound nucleus.

Direct recycling

Direct recycling is a lithium-ion battery recycling method that recovers and regenerates cathode material intact, preserving its crystal structure and avoiding energy-intensive metal extraction and resynthesis.

Direct reduced iron

Direct reduced iron, also called sponge iron or hot-briquetted iron when compacted, is metallic iron made by removing oxygen from iron ore in the solid state without melting.

Direct Rendering Manager

The Direct Rendering Manager (DRM) is the Linux kernel subsystem that coordinates access to graphics hardware, letting multiple 3D applications, a display server, and the kernel share one GPU safely.

Direct RNA sequencing

Direct RNA sequencing, also known as direct RNA-seq, is a nanopore method that reads native RNA molecules single-file through a protein pore, detecting modifications like m6A.

Direct sampling (Monte Carlo)

Direct sampling is a Monte Carlo technique that generates independent, unweighted draws exactly from a target probability distribution by transforming uniform random numbers, without rejecting candidates.

Direct search (optimization)

Direct search is a derivative-free optimization method that improves an objective function by sampling trial points and using function values alone, with no gradients or models.

Direct selling

Direct selling, or direct sales, is a sales channel in which independent contractors sell goods and services to consumers away from fixed retail locations for commission.

Direct sequencing

Direct sequencing is the sequencing of PCR products or genomic DNA without prior cloning, producing an average sequence of all copies for clone verification, allele typing, and mutation identification.

Direct shear test

The direct shear test is a laboratory test that measures the shear strength of soil or rock by sliding one half of a specimen past the other.

Direct simulation Monte Carlo

Direct simulation Monte Carlo (DSMC) is a stochastic, particle-based numerical method for solving the Boltzmann equation in rarefied gas flows, developed by Graeme Bird and first implemented in 1962.

Direct solver

A direct solver is a numerical linear algebra method that solves linear systems by factorizing the matrix, giving the solution in a fixed number of steps.

Direct Sparse Odometry

Direct Sparse Odometry (DSO) is a visual odometry method that estimates camera motion by directly minimizing photometric error, proposed by Engel, Koltun, and Cremers in 2016.

Direct steam generation

Direct steam generation (DSG) is a concentrating solar power technology that produces steam directly in collector receiver tubes, removing the oil loop and heat exchangers for higher efficiency and simpler plants.