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High-entropy electrolyte
A high-entropy electrolyte (HEE) is a battery electrolyte, liquid, gel, or solid, that mixes multiple salts, solvents, or ions to raise disorder, improving ionic conductivity, interfacial stability, and cycling.
High-entropy layered oxide cathodes
High-entropy layered oxide cathodes (HELOs) are battery cathode materials in which five or more cation species share a layered oxide sublattice, stabilizing the structure during cycling.
High-entropy metallic glass
A high-entropy metallic glass is a metallic alloy that combines the multi-principal-element composition of a high-entropy alloy with the amorphous, non-crystalline structure of a metallic glass, made by rapid quenching.
High-entropy oxide electrocatalysts for oxygen evolution
High-entropy oxide electrocatalysts for oxygen evolution are single-phase oxides containing five or more metals that catalyze the oxygen evolution reaction, an alternative to costly iridium and ruthenium catalysts.
High-entropy oxide thermal barrier coatings
High-entropy oxide thermal barrier coatings are thermal barrier coatings whose ceramic topcoat is a high-entropy oxide with five or more cations, candidates to replace yttria-stabilized zirconia.
High-entropy solid electrolytes
High-entropy solid electrolytes (HESEs) are solid ion-conducting battery materials that mix several cations or anions into one disordered lattice, an approach adapted from high-entropy alloys to raise ionic conductivity.
High-entropy thermoelectrics
High-entropy thermoelectrics are thermoelectric materials in which several principal elements share the same lattice sites, stabilizing a single disordered phase that scatters phonons and lowers thermal conductivity.
High-explosive squash head
High-explosive squash head (HESH), known in American usage as high-explosive plastic (HEP), is a shell that flattens plastic explosive on armor and defeats it by spalling.
High-Flyer (幻方)
High-Flyer (幻方) is a Chinese quantitative hedge fund founded in 2015 by Liang Wenfeng, whose AI-driven portfolio peaked at 100 billion yuan before it incubated DeepSeek.
High-frequency Active Auroral Research Program
The High-frequency Active Auroral Research Program, known as HAARP, is an ionospheric research facility in Gakona, Alaska, whose 180-antenna array radiates 3.6 megawatts into the upper atmosphere.
High-frequency transformer
A high-frequency transformer transfers power at frequencies far above the 50 or 60 Hz grid, typically tens of kilohertz, providing galvanic isolation in switched-mode power supplies, DC-DC converters, and solid-state transformers.
High-gain antenna
A high-gain antenna (HGA) is a directional antenna that concentrates radio power into a narrow beam, the principal dish antenna spacecraft use to communicate across interplanetary distances.
High-heeled shoe
A high-heeled shoe raises the heel above the toe, shifting weight forward. Originating in Persian cavalry footwear, it became male aristocratic status wear in Baroque Europe, then women's fashion.
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-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-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-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-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-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 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-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 die casting
High-pressure die casting (HPDC) is a casting process that forces molten metal under pressure into a steel die, filling in a fraction of a second.