61,984 articles
Orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing (OFDM), also called discrete multitone modulation, is a multicarrier modulation technique that splits data across many orthogonal subcarriers, dominant in Wi-Fi, LTE, 5G, and digital television.
Orthogonal projection
Orthogonal (orthographic) projection is a drafting method that represents a three-dimensional object by projecting its edges onto perpendicular planes along parallel projectors, producing the standard views of engineering drawings.
Orthogonal time frequency space modulation
Orthogonal time frequency space (OTFS) modulation is a digital modulation scheme for wireless communication, introduced in 2017, that places symbols on a delay-Doppler grid and outperforms OFDM at high speeds.
Orthorectification
Orthorectification is a remote sensing image processing method that removes geometric distortions from aerial or satellite imagery caused by sensor tilt, viewing geometry, and terrain relief, producing a map-accurate orthoimage.
Orthotropic deck
An orthotropic deck, or orthotropic steel deck, is a lightweight steel bridge deck of rib-stiffened plate and floorbeams acting as one structure, developed in Germany in the 1930s for long-span bridges.
Orvieto Cathedral
Orvieto Cathedral (Italian: Duomo di Orvieto) is the Roman Catholic cathedral of Orvieto in Umbria, Italy, begun in 1290, a major example of Italian Romanesque-Gothic architecture with a mosaic-covered facade.
Orville Carlisle
Orville H. Carlisle (1917–1988) was an American shoe store owner and pyrotechnics hobbyist in Norfolk, Nebraska whose Rock-A-Chute rockets and single-use motor founded model rocketry.
Orville Wright
Orville Wright (1871–1948) was an American aviation pioneer who, with his older brother Wilbur, made the first controlled, powered, sustained flight at Kitty Hawk in 1903.
Oryon
Oryon (Qualcomm Oryon) is a custom 64-bit Arm CPU microarchitecture developed by Qualcomm from Nuvia's designs, powering Snapdragon X Elite PCs and Snapdragon 8 Elite phones.
Oryx Midstream Services
Oryx Midstream Services is a private crude oil gathering company based in Midland, Texas, whose Permian Basin assets merged into the Plains Oryx joint venture in 2021.
Oryx Pipeline System
The Oryx Pipeline System is a crude oil gathering and transportation network in the Permian Basin of West Texas and New Mexico, built around the Oryx Trans Permian pipeline.
OS X El Capitan
OS X El Capitan (version 10.11), also known as OS X 10.11, is the twelfth major release of Apple's OS X desktop operating system, released on September 30, 2015.
OS X Mavericks
OS X Mavericks (version 10.9) is the tenth major release of Apple's Mac operating system, released as a free download on October 22, 2013, with over 200 new features.
OS X Mountain Lion
OS X Mountain Lion (version 10.8) is the ninth major release of Apple's Mac operating system, released in July 2012 with more than 200 new features, mostly ported from iOS.
OS X Yosemite
OS X Yosemite, version 10.10, is the eleventh major release of Apple's Mac operating system, released free on October 16, 2014 with a redesigned interface and Continuity features linking Macs with iPhones and iPads.
OS-9
OS-9 is a real-time, multiuser, multitasking operating system developed by Microware for the Motorola 6809 in 1980, later ported to the 68000 and rewritten in C as OS-9000.
OS/2
OS/2, also known as IBM OS/2, is a discontinued PC operating system first announced by IBM and Microsoft in 1987 and later developed solely by IBM.
Osa Demolition Equipment
Osa Demolition Equipment is an Italian manufacturer of demolition attachments for excavators, including hydraulic hammers, crushers, pulverizers, shears, and sorting grapples, founded by the Sallustio brothers in Molfetta and acquired by Sandvik in 2025.
Osage Pipeline Company
Osage Pipe Line Company is a joint venture of HF Sinclair and CHS that owns a 135-mile crude oil pipeline from Cushing, Oklahoma, to El Dorado, Kansas.
Osaka Castle (大坂城)
Osaka Castle, in Osaka, Japan, was begun in 1583 by Toyotomi Hideyoshi and fell to the Tokugawa in 1615; its 1931 concrete tower houses a museum.
OSAM-2
OSAM-2, also known as Archinaut One, was a NASA technology demonstration mission, developed with Redwire, to 3D-print beams and deploy a solar array in low Earth orbit; it ended in 2023 before flight.
Osama Nayfeh
Osama M. Nayfeh, also published as Sam Nayfeh, is an American electrical engineer and Senior Engineer/Scientist at NIWC Pacific in San Diego, who received a 2014 PECASE award.
Osamu Mishima
Osamu Mishima (三島 修) is a Japanese materials scientist, born in Hiroshima in 1951, whose high-pressure ice experiments at NIMS established polyamorphism and the two amorphous forms of water.
OSATS
OSATS, or Objective Structured Assessment of Technical Skills, is a method for assessing surgical technical skill, in which trainees perform procedures at stations scored by checklists and a global rating scale.
OSBAT Oil Pipeline
The OSBAT oil pipeline (Oleoduto São Sebastião–Cubatão) is a Brazilian crude oil pipeline, in service since 1968, carrying crude from São Sebastião to the Cubatão refinery.
Osborne House
Osborne House is a former royal residence in East Cowes on the Isle of Wight, built between 1845 and 1851 as a seaside retreat for Queen Victoria and Prince Albert.
Osborne Reynolds
Osborne Reynolds was an Anglo-Irish engineer and physicist who held the Chair of Engineering at Owens College, Manchester, from 1868 to 1905 and established the Reynolds number.
OSCAB Oil Pipeline
The OSCAB Oil Pipeline (Oleoduto OCAB) is a 67 km Petrobras crude oil pipeline in Rio de Janeiro state, Brazil, running from Quissamã to the Cabiúnas Terminal in Macaé.
Oscar D. Dubon Jr.
Oscar D. Dubon Jr. is an American materials scientist, professor at UC Berkeley and faculty scientist at Lawrence Berkeley National Laboratory, who won the 2004 Presidential Early Career Award for semiconductor research.
Oscar Niemeyer
Oscar Niemeyer (1907–2012) was a Brazilian architect, a defining figure of Brazilian modern architecture, known for free-flowing concrete curves and for the principal buildings of Brasília, inaugurated in 1960.