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Reference designator
A reference designator (RefDes), often shortened to refdes, is an alphanumeric code such as R23 or C1 that uniquely identifies each component in a schematic, PCB layout, or bill of materials.
Reference material
A reference material (RM) is a material sufficiently homogeneous and stable for a specified measurement use; a certified reference material adds a certificate with property values, uncertainties, and traceability.
Referential integrity
Referential integrity is a database property requiring that every foreign key value matches a referenced key or is null, enforced in SQL by foreign key constraints.
Refill friction stir spot welding
Refill friction stir spot welding, also known as friction spot welding, is a solid-state welding process that joins overlapping light-metal sheets without leaving a keyhole.
RefinedWeb
RefinedWeb is a five-trillion-token English pretraining dataset built by the Technology Innovation Institute from filtered Common Crawl and announced in June 2023, serving as the data foundation of the Falcon language models.
Refinement type
A refinement type is a data type paired with a logical predicate restricting which values it admits, so a static checker can verify program properties at compile time.
Reflect Orbital
Reflect Orbital is an American aerospace startup, founded in 2021 and based in the Los Angeles area, that plans to sell "sunlight on demand" by reflecting sunlight from satellites onto the ground at night.
Reflectarray antenna
A reflectarray antenna is a high-gain antenna whose flat surface of hundreds of phased elements reflects a feed's signal into a collimated beam, first demonstrated in 1963.
Reflected ceiling plan
A reflected ceiling plan (RCP) is a two-dimensional construction drawing showing everything on a ceiling, drawn as if reflected in a mirror on the floor so it aligns with the floor plan.
Reflection AI
Reflection AI is an American artificial intelligence startup founded in 2024 in Brooklyn, New York, by former Google DeepMind researchers Misha Laskin and Ioannis Antonoglou.
Reflection Grating Spectrometer
The Reflection Grating Spectrometer (RGS) is a pair of X-ray spectrometers aboard ESA's XMM-Newton observatory, the first to use reflection gratings, covering the 0.33 to 2.5 keV band.
Reflective semiconductor optical amplifier transmitter
A reflective semiconductor optical amplifier (RSOA) transmitter amplifies an incoming optical carrier and modulates data onto it, serving as a colorless, wavelength-agnostic transmitter in WDM-PON fiber networks.
Reflexion
Reflexion is a 2023 method for improving language-model agents, introduced by Noah Shinn and colleagues: agents write verbal self-assessments of failed attempts into memory, so later retries improve without any weight updates.
Reflow soldering
Reflow soldering, also called solder reflow, is a process for surface-mount electronics assembly in which a controlled oven temperature profile melts solder paste to form joints.
Reformer (transformer model)
Reformer is an efficient Transformer architecture introduced in January 2020 by Kitaev, Kaiser, and Levskaya, using LSH attention and reversible layers to process very long sequences.
Reformulated gasoline blendstock
Reformulated gasoline blendstock, or RBOB, is a low-volatility, low-octane petroleum blendstock shipped to fuel terminals, where ethanol is blended in to produce reformulated gasoline under the Clean Air Act.
Refractory
A refractory, or refractory material, is a non-metallic ceramic that withstands 1,000 °F or above, lining furnaces, kilns, and boilers, with about 70% of production used in steelmaking.
Refractory high-entropy alloys
A refractory high-entropy alloy (RHEA) is a high-entropy alloy of refractory metals such as niobium, tantalum, molybdenum, and tungsten, typically containing at least five elements, first designed in 2010.
Refresh rate
Refresh rate, also called vertical refresh rate or vertical scan rate, is the frequency in hertz at which a display redraws the entire screen image, typically about 60 times per second.
Refrigerant
A refrigerant, sometimes called refrigerant gas, is the working fluid in refrigeration, air-conditioning, and heat pump systems, absorbing heat by evaporation and rejecting it by condensation; HFCs are being phased down for their climate impact.
Refrigerated truck
A refrigerated truck, commonly called a reefer truck, is an insulated truck with an onboard refrigeration unit holding temperature-sensitive cargo like food, pharmaceuticals, and medical supplies.
Refrigeration
Refrigeration is the process of removing heat from a space or substance to keep it below the surrounding temperature, achieved mainly by vapor-compression cycles that circulate a refrigerant.
Refrigerator
A refrigerator, or fridge, is a household appliance that uses a mechanical refrigeration cycle to stay at 40 °F (4 °C) or below, keeping perishable food safe for days or weeks.
Refrigerator car
A refrigerator car, or reefer, is an insulated railroad freight car cooled by ice and later mechanical refrigeration, used to carry meat, fruit, and other perishables over long distances.
ReFS
ReFS (Resilient File System) is a Microsoft file system introduced in 2012 for Windows Server, designed to complement NTFS with checksums, self-healing, and volumes up to 35 petabytes.
RefSeq
RefSeq, short for Reference Sequence, is a database maintained by the US National Center for Biotechnology Information that provides curated, non-redundant reference sequences of genomic DNA, transcripts, and proteins for diverse organisms.
Reftinskaya GRES power station
Reftinskaya GRES (Рефтинская ГРЭС) is a coal-fired power station in Reftinsky, Sverdlovsk Oblast, Russia. Opened in 1970, its 3,800 MW make it the largest coal-fired plant in Russia.
ReFuelEU Aviation
ReFuelEU Aviation is a 2023 EU regulation requiring sustainable aviation fuel at EU airports, starting at 2% in 2025 and rising to 70% by 2050.
ReFuelEU Aviation SAF blending mandate
The ReFuelEU Aviation SAF blending mandate, created by EU Regulation 2023/2405, requires fuel suppliers at EU airports to blend rising shares of sustainable aviation fuel from 2% in 2025.
Refurbishment (electronics)
Refurbishment of electronics is the repair or upgrade of used devices for resale, with testing and data wiping; a refurbished smartphone showed 71% lower emissions than a new one.