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Low Earth orbit
Low Earth orbit (LEO) is the region of Earth orbit between roughly 200 and 2,000 km altitude, where satellites complete a revolution in 88 to 127 minutes.
Low Earth orbit satellite population
The low Earth orbit satellite population is the set of objects below 2,000 km altitude: about 34,000 cataloged objects, roughly 16,000 active satellites, and millions of modeled debris pieces.
Low frequency
Low frequency (LF) is the ITU band 5 of the radio spectrum, from 30 to 300 kHz, valued for stable ground-wave propagation over long distances.
Low Income Home Energy Assistance Program
The Low Income Home Energy Assistance Program (LIHEAP) is a US federal block grant program helping low-income households pay home energy bills, created in 1981.
Low lunar orbit
A low lunar orbit (LLO) is an orbit around the Moon tens to about a hundred kilometers up, completed roughly every two hours and destabilized by lunar mascons.
Low NOx burner
A low NOx burner (LNB) is a combustion burner that reduces nitrogen oxide emissions by staging the mixing of fuel and air within the burner itself.
Low Orbit Ion Cannon
Low Orbit Ion Cannon (LOIC) is an open-source network stress-testing application that floods servers with TCP, UDP, or HTTP traffic, best known as a DDoS tool used by Anonymous.
Low Visibility Operations
Low Visibility Operations are aircraft takeoffs, approaches, landings, and taxi operations conducted when visibility falls below values permitting normal operation, with thresholds set by aviation regulators.
Low-activation steel
Low-activation steel, usually called reduced-activation ferritic/martensitic (RAFM) steel, is a chromium martensitic steel for fusion reactors whose alloys, replacing molybdenum with tungsten, decay to hands-on activity within roughly a century.
Low-carbon concrete
Low-carbon concrete is concrete designed to cut greenhouse-gas emissions, chiefly by replacing Portland cement clinker with supplementary cementitious materials like fly ash, slag, or calcined clay.
Low-cost carrier
A low-cost carrier, also called a budget or discount airline, offers lower fares by cutting included services and charging for extras, pioneered by Southwest Airlines in the 1970s.
Low-cost Uncrewed Combat Attack System
The Low-cost Uncrewed Combat Attack System is a US Air Force effort to build cheap, jet-powered, expendable attack drones, the ancestor of its Collaborative Combat Aircraft program.
Low-definition television
Low-definition television (LDTV) is a television format with resolution lower than standard-definition television, roughly MPEG-1 quality, used for mobile broadcasts such as Japan's 1-seg service.
Low-dropout regulator
A low-dropout regulator (LDO) is a linear voltage regulator that maintains its output voltage even when the input is only slightly higher than the output.
Low-emissivity coating
A low-emissivity (low-E) coating is a microscopically thin transparent coating on glass or plastic that reflects infrared heat while transmitting visible light, reducing heat transfer through windows.
Low-emissivity glass
Low-emissivity glass, or low-e glass, is window glass carrying a microscopically thin, virtually invisible metal coating that reflects infrared heat while transmitting visible light, reducing heat transfer through windows.
Low-energy transfer
A low-energy transfer (LET) is a spacecraft trajectory between two bodies, such as Earth and the Moon, that uses a third body's gravity to save propellant.
Low-enriched uranium
Low-enriched uranium (LEU) is uranium enriched to less than 20 percent uranium-235 and the standard fuel for commercial power reactors, typically at 3 to 5 percent.
Low-gain antenna
A low-gain antenna (LGA) is a spacecraft antenna that broadcasts over wide directions, maintaining a link with ground stations without precise pointing, typically below 8 to 10 dBi.
Low-impact development
Low-impact development (LID) is a stormwater management approach that manages rainwater close to where it falls using practices like rain gardens, permeable pavement, and green roofs.
Low-iron solar glass
Low-iron solar glass, also called ultra-clear or photovoltaic glass, is soda-lime glass with reduced iron content, the front cover of photovoltaic modules that lets more sunlight reach the cells.
Low-k dielectric
A low-k dielectric is an insulating material with a low dielectric constant that fills the space between copper wires in an integrated circuit, reducing capacitance, signal delay, and power dissipation.
Low-level programming language
A low-level programming language provides little or no abstraction from a computer's instruction set architecture, so its code runs directly on the processor; machine code and assembly language are the standard examples.
Low-level waste
Low-level waste (LLW) is a category of radioactive waste that accounts for about 90 percent of radioactive waste volume worldwide but only about 1 percent of its radioactivity.
Low-level waste disposal
Low-level waste disposal is the permanent emplacement of low-level radioactive waste in licensed near-surface facilities, using engineered and natural barriers while radioactive decay reduces the hazard.
Low-noise amplifier
A low-noise amplifier (LNA) is an electronic amplifier placed as the first stage of a receiver chain, boosting weak signals while adding as little noise as possible.
Low-noise block downconverter
A low-noise block downconverter, or LNB, is the device at a satellite dish's focus that amplifies the weak signal and converts it for coaxial cable.
Low-pass filter
A low-pass filter, also called a high-cut or treble-cut filter, is a circuit or algorithm that passes signals below a chosen cutoff frequency and attenuates signals above it.
Low-pressure chemical vapor deposition
Low-pressure chemical vapor deposition (LPCVD) is a thin-film deposition technique that coats batches of wafers with polysilicon, silicon nitride, or silicon dioxide in a heated furnace at a small fraction of atmospheric pressure.
Low-rank adaptation
Low-rank adaptation (LoRA) is a parameter-efficient fine-tuning technique, proposed by Edward J. Hu and colleagues at Microsoft in 2021, that freezes pre-trained model weights and trains small low-rank matrices.