Engineering

Gas-discharge lamp: principles, types, history, and uses Gas discharge lamp Overview of gas-discharge lamps: how they work, main types (fluorescent, sodium, neon, metal-halide), advantages, history and environmental considerations, and comparison with LEDs…

Gas turbine (combustion turbine) Gas turbine A gas turbine is a rotary internal combustion engine that produces mechanical power from expanding hot gases; used for power generation, propulsion, and mechanical drive applicatio…

Gauge (measurement instrument) Gauge A gauge is an instrument or display that indicates the magnitude of a physical quantity. It may be mechanical, electrical, or digital and is used across weather, transport, industr…

Gear: design, types, materials, history and common uses Gear An overview of gears: definition, design principles, major types, materials, manufacturing methods, history, applications and common maintenance and selection considerations.

Geotechnical Engineering: Principles, Practice, and Applications Geotechnical engineering Study and engineering of earth materials and foundations, covering soil and rock behavior, site investigation, design of foundations and earthworks, slope stability, and ground imp…

Glen Canyon Dam: overview, design, history, uses and controversies Glen Canyon Dam Glen Canyon Dam on the Colorado River forms Lake Powell. Built in the mid-20th century, it provides water storage, flood control, hydropower and recreation while generating signifi…

Glow fuel for model engines Glow fuel Glow fuel is a methanol-based fuel blend used to power small model airplane, car, boat and helicopter engines. This article explains composition, operation, typical blends, lubrica…

Grade (slope) of a road or railway Grade (slope) The grade (or gradient) measures how steep a road, track or terrain is. Presented as a percentage, ratio, per mille or angle, it affects design, safety and vehicle performance.

Grand Coulee Dam Large concrete dam on the Columbia River in Washington (U.S.), completed in the 1940s; supplies irrigation, flood control, recreation and the largest single hydroelectric power cap…

Grappling hook A grappling hook is a multi-pronged hook attached to a line, used historically in maritime and siege work and today for rescue, tactical retrieval, and specialized climbing or anch…

Grashof number Dimensionless number measuring the ratio of buoyancy to viscous forces in a fluid; used to characterize natural (free) convection and relate to Rayleigh and Prandtl numbers.

Great Belt Fixed Link (Storebæltsforbindelsen) Great Belt Fixed Link Major Danish transport connection of bridges and a rail tunnel across the Great Belt, linking the islands of Zealand and Funen and carrying road and rail traffic since the 1990s.

Grid (networks, layouts, and systems) Grid A grid is a regular network of intersecting lines or nodes used across mapping, design, science and infrastructure. This article explains types, history, uses, and notable variatio…

Gristmill: history, design, and role in grinding grain Gristmill An overview of the gristmill — its purpose, main parts, power methods (water, wind, animal), historical development, and cultural importance in producing flour from grain.

Groove (joinery) In woodworking joinery, a groove is a long slot cut parallel to the grain to receive panels, drawer bottoms, or tongues; it has several forms, tools, and uses distinct from dados a…

Gunsmith: craft, history, and role in firearm maintenance Gunsmith A gunsmith designs, builds, repairs and modifies firearms. This article explains skills, common tasks, historical development, differences from an armorer, tools, and modern import…

Harmonic damper (crankshaft torsional vibration damper) Harmonic damper A harmonic damper reduces torsional vibration in engine crankshafts. It mounts on the free end of the crankshaft and uses mass, elastomeric elements, or fluid to absorb resonant os…

Heat engine Device that converts heat into mechanical work by exploiting a temperature difference between a hot source and a cold sink; includes types, cycles, history, uses and limits.

Heat exchanger A heat exchanger transfers thermal energy between fluids or between a fluid and a surface. Designs, operation, history, and common applications are described with key distinctions…

Heating: systems, methods, and uses Heating Overview of heating: what it is, common systems and components, historical development, technologies (boilers, furnaces, heat pumps), uses, efficiency, safety, and distinctions lik…

Heating oil (No. 2 fuel oil): uses, storage, safety and environmental issues Heating oil Heating oil, commonly called No. 2 fuel oil, is a middle‑distillate petroleum product used to heat buildings. This entry covers grades, storage, delivery, safety, contamination, an…

Heavy equipment Heavy equipment refers to powerful machines used in construction, earthmoving, mining, and similar work. They rely on hydraulics, traction, and trained operators to move material e…

Helicopter rotor: function, types, components and history Helicopter rotor Rotors are the rotating lifting surfaces of helicopters. This article explains how they work, main parts, rotor arrangements, control systems, historical development and operationa…

Helipad (helicopter landing pad) Helipad A helipad is a designated landing surface for helicopters, found on ground sites, rooftops, ships and temporary locations. It includes marked touchdown areas, lighting and safety z…

Hello, World! program Hello world program An introductory program that prints “Hello, World!” to demonstrate basic syntax and verify a language environment; commonly used as a first example in programming tutorials.

High-voltage direct current (HVDC) High-voltage direct current HVDC is the transmission of electric power using high-voltage direct current. It is used for long-distance links, submarine cables, and connecting asynchronous power systems with e…

Hinge — function, parts, types, uses, and history Hinge A hinge is a mechanical bearing that connects two bodies and allows controlled rotation. This article explains parts, common types, applications, installation, maintenance and a br…

Hoist (lifting device) Hoist A hoist is a mechanical apparatus for raising and lowering loads using rope, chain, or cable around a drum or wheel. It can be manual, electric, or pneumatic and is used in constru…

Hose: Flexible Tubing for Fluids and Gases Hose A hose is a flexible tube used to convey liquids or gases. This article explains construction, materials, common types, history, uses and safety considerations for hoses.

Hydraulics: principles, components, history and applications Hydraulics Hydraulics is the engineering discipline that uses the mechanical behavior of liquids to transmit power and control machines. Covers principles, parts, history, and common uses.

Hydroelectricity: generation, components, history, and impacts Hydroelectricity Hydroelectricity converts moving water into electricity using turbines and generators. This article explains how it works, main components, history, benefits, drawbacks, and notabl…

Hydropower: energy harnessed from moving water Hydropower Hydropower converts the kinetic and potential energy of flowing or falling water into useful mechanical or electrical energy. This article explains methods, components, history, us…

I²C (Inter-Integrated Circuit) bus I²C I²C (I2C) is a two-wire serial communications bus for connecting integrated circuits and microcontrollers, supporting multi-master systems, simple wiring, and common sensor/periphe…

IEC 61850 — Communication Standard for Power Utility Automation IEC 61850 IEC 61850 is an international standard defining data models, communications and configuration for automation of electrical substations, enabling interoperable, Ethernet-based prote…

Ignition system Overview of ignition systems: purpose, main types and components, historical development, typical uses in engines, maintenance concerns, and distinctions between ignition methods.

Image processing: principles, methods, history and applications Image processing Overview of image processing: core concepts, main steps, technical approaches, historical development and common applications across science, industry and everyday imaging.

Impedance matching in electronics and optics Impedance matching Impedance matching is the practice of making two systems interact with minimal signal reflection or loss. It applies to electrical circuits, RF systems, audio gear, and optical int…

Induction coil (spark coil) — early high-voltage pulse transformer Induction coil A device that converts low-voltage direct current into high-voltage pulses by interrupting the primary circuit; historically important for X‑rays, spark transmitters and arc lighti…

Induction heating: principles, equipment, applications and key facts Induction heating Induction heating uses time-varying magnetic fields to induce currents and heat inside conductive materials. This article outlines how it works, equipment, history, common uses and…

Industrial engineering: systems design, optimization and real-world applications Industrial engineering Industrial engineering improves systems that deliver goods and services by optimizing people, processes, technology and resources for quality, safety, productivity and sustainabili…

Infrastructure: systems, components, history and societal importance Infrastructure Overview of infrastructure — its main elements, historical development, social and economic roles, common challenges, and distinctions between physical, social and digital systems.

Ingénieur des études et de l'exploitation de l'aviation civile (IEEAC) Ingénieur des études et de l'exploitation de l'aviation civile French civil service engineering corps responsible for technical studies and operational oversight in civil aviation; trained partly at ENAC and employed by national aviation autho…

Inheritance in Object-Oriented Programming Inheritance (object-oriented programming) Inheritance is an OOP mechanism where a class acquires properties and behavior from another, enabling specialization, code reuse, and polymorphism while introducing design trade-of…

Inline-four engine (I4/L4): design, balance, and common uses Inline-four engine Overview of the inline-four (I4/L4) engine: layout, mechanical characteristics, balance issues, historical adoption, typical applications, and common variants.

Instruction-level parallelism (ILP): concepts, techniques, and practical limits Instruction level parallelism Instruction-level parallelism (ILP) describes the extent to which a program’s individual instructions can be executed simultaneously. This article explains ILP, measurement, techni…

Instruction pipelining in CPUs: design, stages, hazards and performance Instruction pipelining Instruction pipelining is a microarchitectural technique that increases instruction throughput by dividing execution into overlapping stages. This article explains how it works, co…

Instruction set (Instruction set architecture) Instruction set An instruction set (ISA) defines the operations a processor can perform, their encodings and effects. It is the programmer-facing part of computer architecture, distinct from imple…

Instrument rating (pilot qualification) Instrument rating Qualification that permits a pilot to operate aircraft under Instrument Flight Rules (IFR); involves instrument navigation, procedures, training and regulatory testing.