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High-pressure fuel pump
A high-pressure fuel pump raises fuel from tank pressure to injection pressure in direct-injection engines, feeding the common rail; diesel systems reach up to 2,700 bar.
High-pressure grinding rolls
High-pressure grinding rolls (HPGR) are comminution machines that crush rocks and ores between two counter-rotating rollers, cutting grinding energy use by 20–40% in mining and cement.
High-pressure sodium lamp
The high-pressure sodium lamp (HPS lamp) is a high-intensity discharge lamp producing warm orange-white light, developed by General Electric and widely used for street lighting.
High-pressure torsion
High-pressure torsion is a severe plastic deformation technique that twists a metal disk under several gigapascals of pressure, refining its grains to raise strength and hardness.
High-pressure water scrubbing
High-pressure water scrubbing is a biogas upgrading technology that removes carbon dioxide by dissolving it in pressurized water, historically the most widely used upgrading method worldwide.
High-resolution audio
High-resolution audio (Hi-Res Audio) is a class of digital audio formats whose sampling rates and bit depths exceed the compact disc's, typically 96 kHz/24-bit PCM or DSD, with industry definitions adopted in 2014.
High-speed machining
High-speed machining (HSM) is a metal-cutting practice using speeds far above conventional machining, first explored by Carl Salomon in the 1920s and applied in aerospace, automotive, and mold making.
High-speed photography
High-speed photography is an imaging technique that records fast events as ordered image sequences, at frame rates from a few hundred to hundreds of millions per second.
High-speed rail
High-speed rail, also known as HSR, is railway service at speeds of at least 250 km/h on new lines, pioneered by Japan's Tokaido Shinkansen in 1964.
High-speed rail in China
High-speed rail in China (中国高速铁路) is the world's largest high-speed network, at 48,000 km by the end of 2024, begun with the Beijing–Tianjin line in 2008.
High-speed rail in Europe
High-speed rail in Europe is a network of specially built and upgraded lines, concentrated in Spain, France, Italy, and Germany, with trains running above 250 km/h on new lines.
High-speed rail in India
High-speed rail in India: the 508 km Mumbai–Ahmedabad Shinkansen-technology corridor (350 kmph design, ₹1.08 lakh crore, 81% JICA-funded, first service expected August 2027) plus the Vande Bharat semi-high-speed programme and seven planned corridors.
High-speed rail in Indonesia
High-speed rail in Indonesia consists of the Whoosh line linking Jakarta and Bandung, opened in 2023 as Southeast Asia's first high-speed railway, reaching 350 km/h.
High-speed rail in Morocco
High-speed rail in Morocco consists of the Al Boraq service, Africa's first and only high-speed line, running since 2018 between Tangier and Casablanca, operated by ONCF.
High-speed rail in the United Kingdom
High-speed rail in the UK consists of High Speed 1, a line from London St Pancras to the Channel Tunnel, and High Speed 2, under construction to Birmingham.
High-speed rail in the United States
High-speed rail in the United States is passenger rail expected to sustain speeds above 125 mph, now limited to Amtrak's Northeast Corridor with lines under construction in California and Nevada.
High-speed steel
High-speed steel (HSS) is a high-carbon, high-alloy tool steel, alloyed with tungsten, molybdenum, chromium, and vanadium, which keeps its cutting hardness at approximately 600 °C and is used mostly for machining tools.
High-strength pipeline steel
High-strength pipeline steel is line pipe steel of grade X80 and above in the API 5L system, used for large-diameter, high-pressure oil and gas pipelines.
High-tech architecture
High-tech architecture, also known as Structural Expressionism, is a style that emerged in 1970s Britain and celebrates technology by exposing a building's structure and mechanical services on its exterior.
High-temperature co-electrolysis of steam and CO2
High-temperature co-electrolysis of steam and CO2 is a process in which a solid oxide electrolyzer cell at 650–900 °C turns renewable electricity, water, and CO2 into synthesis gas.
High-temperature gas-cooled reactor
A high-temperature gas-cooled reactor (HTGR) is a graphite-moderated, helium-cooled nuclear reactor with ceramic-coated TRISO fuel, reaching coolant temperatures of 700–950 °C; China's HTR-PM became the first commercial-scale plant in 2023.
High-temperature phase-change materials
High-temperature phase-change materials are substances that store thermal energy as latent heat while melting and solidifying above about 300 °C, for use in concentrated solar power and industrial waste-heat recovery.
High-temperature steam electrolysis
High-temperature steam electrolysis (HTSE) splits steam into hydrogen and oxygen using solid oxide electrolysis cells at 500–1000 °C, needing roughly 35% less electricity than conventional low-temperature electrolysis.
High-temperature superconducting magnet
A high-temperature superconducting magnet is an electromagnet wound from REBCO tape or Bi-2212 wire that stays superconducting at far warmer temperatures, enabling fields above 20 T and compact fusion tokamaks.
High-throughput diffusion multiples
A high-throughput diffusion multiple is an assembly of three or more metal blocks annealed together so diffusion creates a composition-gradient materials library for rapid phase diagram mapping.
High-throughput electrocatalyst screening by thin-film sputtering
High-throughput electrocatalyst screening by thin-film sputtering is a materials-discovery method in which sputtered thin-film libraries on one substrate are screened to find catalysts for reactions like hydrogen and oxygen evolution.
High-velocity oxy-fuel spraying
High-velocity oxy-fuel (HVOF) spraying is a thermal spray process burning fuel and oxygen to form a supersonic jet that produces dense, hard coatings, developed in the early 1980s.
High-voltage direct current
High-voltage direct current (HVDC), also called high-voltage DC, transmits electrical power as direct current at high voltage, used for long-distance bulk transmission, submarine cables, and connecting unsynchronized AC grids.
High-voltage direct current cable
A high-voltage direct current (HVDC) cable is a power cable that carries electricity at direct current over long submarine and underground distances where AC cables become inefficient.
High-voltage pulse fragmentation
High-voltage pulse fragmentation is a comminution method in which short, high-voltage discharges in liquid break composites selectively along material interfaces, used mainly for recycling photovoltaic modules, concrete, and batteries.