All articles starting with H
20,046 articles
High-intensity discharge lamp
A high-intensity discharge (HID) lamp is an electric lamp that makes light with an electric arc through vaporized metal compounds; the main types are mercury vapor, metal halide, and high pressure sodium.
High-intensity interval training
High-intensity interval training (HIIT), including the Norwegian 4x4 protocol of four 4-minute bouts at 85-95% max heart rate, alternates short intense exercise bouts with recovery; it raises VO2max and cardiac function and is used in cardiac rehabilitation.
High-intensity training
High-intensity training (HIIT, SIT, RST): repeated short bursts at ≥90% VO2max or >75% maximal power with recovery periods; improves VO2max, anaerobic capacity, and cardiometabolic health comparably to continuous training in less time.
High-k dielectric
A high-k dielectric is an insulator with a dielectric constant far above silicon dioxide's, used in semiconductor manufacturing to replace SiO2 in MOSFET gates and DRAM capacitors, reducing leakage.
High-Level Data Link Control
High-Level Data Link Control (HDLC) is a bit-oriented, layer 2 protocol family standardized by ISO/IEC in ISO/IEC 13239:2002 for transmitting synchronous data between point-to-point and multipoint stations.
High-Level Expert Group on Artificial Intelligence
The High-Level Expert Group on Artificial Intelligence (AI HLEG) is a 52-member expert group appointed by the European Commission in 2018 that drafted the EU's Ethics Guidelines for Trustworthy AI.
High-level modulation
High-level modulation is an AM generation method in which audio is applied to a transmitter's final, highest-power stage, allowing efficient class C amplification; it dominated broadcast design for over 60 years.
High-level programming language
A high-level programming language is a programming language independent of any specific computer's machine language, translated by a compiler or interpreter; FORTRAN was the first, from 1954.
High-level synthesis
High-level synthesis (HLS) is a method that translates untimed C, C++, SystemC, or OpenCL code into timed register-transfer level hardware designs in Verilog or VHDL.
High-level trigger
The high-level trigger (HLT) is the software-based second stage of event selection at particle collider experiments, used at the LHC by ATLAS, CMS, and LHCb.
High-lift device
A high-lift device is a movable wing component, such as a trailing-edge flap or leading-edge slat, deployed during takeoff and landing to increase lift at low speeds.
High-linolenic flaxseed oil
High-linolenic flaxseed oil, or high-ALA flaxseed oil, is edible flaxseed oil with about 70% alpha-linolenic acid versus ~50% conventional, granted FDA GRAS no-questions status as GRN 256 (Polar Foods, 2009).
High-Luminosity Large Hadron Collider
The High-Luminosity Large Hadron Collider (HL-LHC, also HiLumi LHC) is a CERN upgrade replacing parts of the 27-kilometer LHC with new superconducting magnets to multiply its data tenfold, operating from mid-2030.
High-net-worth individual
A high-net-worth individual (HNWI), or high-net-worth client, is a person with at least USD 1 million in investable assets excluding the primary residence, a wealth-management convention from 1997.
High-nutrient, low-chlorophyll region
A high-nutrient, low-chlorophyll (HNLC) region is an open-ocean area where surface waters hold plentiful nitrate and phosphate year-round, yet phytoplankton stays scarce, chiefly because iron is depleted.
High-occupancy vehicle lane
A high-occupancy vehicle lane, also called a carpool or HOV lane, is a roadway lane reserved for vehicles carrying at least two occupants, such as carpools, vanpools, and buses.
High-oleic, low-linolenic soybean oil
High-oleic, low-linolenic soybean oil (HOSBO) is breed-modified soybean oil with about 72-85% oleic and under 3% linolenic acid, giving frying stability without hydrogenation; regulated via FDA GRN 306 and commercial since 2011.
High-order control barrier functions
High-order control barrier functions are a control theory construction, introduced by Wei Xiao and Calin Belta in 2019, extending control barrier functions to safety constraints of high relative degree.
High-output heart failure
High-output heart failure (HOHF): heart failure with cardiac output >8 L/min or CI >4 L/min/m2, low systemic vascular resistance; caused by obesity, cirrhosis, AV shunts, anemia; vasodilators worsen it.
High-pass filter
A high-pass filter, also known as a low-cut or bass-cut filter, passes signals above its cutoff frequency and attenuates lower ones, blocking DC while passing AC.
High-performance anion-exchange chromatography
High-performance anion-exchange chromatography (HPAEC) is a liquid chromatography technique that separates carbohydrates and other anions in strongly alkaline eluents, introduced by Rocklin and Pohl in 1983 and usually paired with pulsed amperometric detection.
High-performance computing
High-performance computing (HPC) is the practice of linking many computers to solve problems too large for a single machine, used in weather forecasting, genomics, and physics.
High-performance concrete
High-performance concrete (HPC) is concrete meeting special performance requirements like high strength or low permeability, usually through a reduced water-to-cement ratio and materials such as silica fume.
High-performance liquid chromatography
High-performance liquid chromatography, also written high-pressure liquid chromatography, is an analytical technique that pumps a dissolved sample through a packed column to separate its components. It dominates pharmaceutical analysis.
High-performance liquid chromatography–electrospray ionization tandem mass spectrometry
High-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI-MS/MS) is an analytical method that separates compounds by liquid chromatography, ionizes them by electrospray, and quantifies them by two mass-analysis stages, dominant in clinical diagnostics.
High-performance thin-layer chromatography
High-performance thin-layer chromatography (HPTLC) is a planar chromatography technique that separates compounds on plates with fine particles, giving better resolution than conventional TLC at low cost.
High-power impulse magnetron sputtering
High-power impulse magnetron sputtering, also called high power pulsed magnetron sputtering, is a physical vapor deposition technique that applies short, high-power pulses to ionize sputtered atoms.
High-power rocketry
High-power rocketry is the branch of amateur sport rocketry using motors of H impulse class and above, over 160 Newton-seconds, with fliers certified by national associations.
High-pressure acid leaching
High-pressure acid leaching (HPAL) is a hydrometallurgical process that extracts nickel and cobalt from laterite ores with sulfuric acid in pressurized autoclaves at roughly 250 °C, producing battery-grade nickel feedstock.
High-pressure area
A high-pressure area, also known as an anticyclone or high, is a region where surface pressure exceeds that of surrounding air, bringing sinking air, light winds, and dry, settled weather.