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Recoilless rifle
A recoilless rifle, or recoilless gun, is a light weapon that vents propellant gas backward to cancel recoil, giving infantry artillery-sized firepower from World War II onward.
Recombination layers in tandem solar cells
A recombination layer, also called the interconnecting layer (ICL), is the thin internal layer that connects the stacked sub-cells of a tandem solar cell in series so their voltages add.
Recommender system
A recommender system, also called a recommendation system or recommendation engine, is software that suggests items a user is likely to value, used by Google, Netflix, and Amazon.
Recomodulin
Recomodulin (リコモジュリン; generic name thrombomodulin alfa, development code ART-123) is a recombinant anticoagulant marketed in Japan by Asahi Kasei for disseminated intravascular coagulation, approved in 2008.
Recon Technology
Recon Technology, Ltd is a China-based oilfield services company traded on NASDAQ under the ticker RCON, providing automation equipment, software, and services mainly to CNPC and Sinopec.
Reconductoring
Reconductoring is the replacement of the wires on an existing overhead transmission or distribution line with new conductors, reusing existing towers and rights of way to increase capacity.
Reconfigurable atom arrays
Reconfigurable atom arrays are a quantum computing architecture in which neutral atoms trapped in movable optical tweezers give qubits arbitrary connectivity, enabling the first many-logical-qubit processor in 2023.
Reconfigurable computing
Reconfigurable computing is the practice of computing on programmable hardware such as FPGAs, combining hardware speed and energy efficiency with software flexibility by changing circuits during operation.
Reconfigurable intelligent surface
A reconfigurable intelligent surface (RIS) is a planar array of mostly passive electromagnetic elements that redirect and focus radio waves under software control, investigated as a 6G technology.
Reconfigurable magnetic metamaterials
Reconfigurable magnetic metamaterials are architected materials whose shape, stiffness, or wave-propagation properties can be changed on demand by an external magnetic field, often using magnetorheological elastomers.
Reconfigurable metamaterial
A reconfigurable metamaterial is an artificial material built from engineered subwavelength structures whose response can be changed after fabrication by heat, light, mechanical deformation, or an electromagnetic field.
Reconfigurable optical add-drop multiplexer
A reconfigurable optical add-drop multiplexer (ROADM) is the optical routing node of a fiber network, adding or dropping any wavelength under software control, introduced commercially in the early 2000s.
Reconfigurable zoned neutral-atom architecture
A reconfigurable zoned neutral-atom architecture is a quantum processor design, introduced by a Harvard-led team in 2023, dividing optical-tweezer-trapped neutral atoms into storage, entangling, and readout zones that atoms physically move between mid-computation.
Reconnaissance aircraft
A reconnaissance aircraft, or spyplane, is a military aircraft whose main mission is gathering information using cameras, radar, and signals equipment rather than weapons, spanning spy planes and drones.
Reconnaissance Energy Africa
Reconnaissance Energy Africa (ReconAfrica) is a Canadian junior oil and gas company exploring in the Kavango Sedimentary Basin of northeastern Namibia and northwestern Botswana, upstream of the Okavango Delta, and listed on the TSX Venture Exchange.
Reconnaissance satellite
A reconnaissance satellite, also known as a spy satellite, is an unmanned spacecraft in orbit that collects intelligence, chiefly imagery and intercepted signals; the first successes reached orbit in 1960.
Reconstruction after the Great Kantō earthquake
Reconstruction after the Great Kantō earthquake, known as the Imperial Capital Reconstruction, rebuilt Tokyo and Yokohama after the September 1923 disaster under Home Minister Gotō Shinpei.
Reconstruction of Kyiv after World War II
The reconstruction of Kyiv after World War II was the Soviet-led rebuilding of the Ukrainian capital after its liberation in November 1943, reshaping Khreshchatyk and housing.
Record (computer science)
In computer science, a record, also known as a struct, is a data structure that groups a fixed set of named fields into a single object.
Record labels v. Suno and Udio
Record labels v. Suno and Udio refers to twin copyright lawsuits filed June 24, 2024, by Universal, Sony, and Warner against AI music generators Suno and Udio.
Recovery factor
The recovery factor is the percentage of hydrocarbons originally in a reservoir that can be produced with current technology, ranging from 1% for tight reservoirs to 80%.
Recraft
Recraft is a family of proprietary text-to-image models for professional design work, best known for its V3 model, which topped the Artificial Analysis leaderboard in October 2024.
Recrystallization (metallurgy)
Recrystallization, also called static recrystallisation, is a metallurgical annealing process in which new strain-free grains form in a cold-worked metal, lowering hardness and strength while increasing ductility.
Rectangular Micro QR Code
The Rectangular Micro QR Code, or rMQR code, is a rectangular two-dimensional barcode symbology developed by Denso Wave, the creator of the QR Code, and standardized in ISO/IEC 23941:2022.
Rectangular rapid-flashing beacon
A rectangular rapid-flashing beacon, or RRFB, is a pedestrian-actuated US traffic device whose two yellow LED beacons flash rapidly at crosswalks, with motorist yielding rates as high as 98 percent.
Rectangular waveguide
A rectangular waveguide is a hollow metallic tube of rectangular cross-section that guides microwaves; its dominant TE10 mode propagates only above a cutoff frequency set by the broad wall.
Rectenna
A rectenna is a device combining an antenna and a rectifier to convert electromagnetic radiation into direct current, first demonstrated by William C. Brown in 1964.
Rectified flow
Rectified flow is a generative training method, introduced by Liu et al. in 2022, that learns an ODE moving noise to data along nearly straight paths for few-step generation.
Rectifier
A rectifier, also called an AC to DC converter, is an electrical circuit that converts alternating current into one-direction direct current, and is built into most power supplies.
Rectifier (neural networks)
The rectifier, best known as the rectified linear unit or ReLU, is an activation function that outputs positive inputs unchanged and zero otherwise, and became the default nonlinearity of deep learning.