Chemical formula for Hydrogen Iodide.
Hidden Line
Broken line used to signify a line that normally would not be seen in a drawing.
Hidden Lines
Broken lines used to signify lines that normally wouldn't be seen in a drawing.
High Carbon Steel
Steel with a carbon content greater than 0.85%.
High Current Arc Ignition Test
Required testing for a material that is in contact with or in close proximity to uninsulated live parts (typically 0.80 mm for non-arcing parts or 12.5 mm for arcing parts).
High Frequency
The portion of the electromagnetic spectrum between 3000 kHz and 30,000 kHz.
High Impact Characteristics
Product and/or process characteristics that, when outside of the specification tolerance, severely affect subsequent manufacturing operations or customer satisfaction.
High Level Language
A computer language with commands that do not directly represent the machine instructions.
High Pass Filter
A filter that passes signal frequencies above a specific, or cut off, frequency is called a high pass filter.
High Performance Liquid Chromatography
An efficient form of column chromatography that pumps a liquid solution of the sample at very high pressure through a column packed with a stationary phase made of very tiny particles.
High Performance Vehicle
A vehicle designed with high levels of performance in certain areas. Normally high power engine to give high accleration rates or top speed.
High Power Effects
Interference effects that occur in the presence of strong signals.
High Speed Steel
About 6 times harder than carbon steel and used extensively for machine tools.

High Spin Complex
A metal-ligand complex with the same number of unpaired electrons as the uncomplexed metal ion.
High Temperature Proton Exchange Membrane Fuel Cell
A variant of the PEMFC which uses a mineral acid based electrolyte rather than an aqueous one and can operate at temperatures up to 200°C.
High Tension
A comparative term used in electronics to denote high voltages.
High Tension Leads
High voltage wire from the ignition coil.
High Voltage Arc Resistance to Ignition Test
Required by various end-product standards when the material is used in contact with uninsulated live parts.
High Voltage Arc Tracking Rate
Required of the material when it is used in contact with or in close proximity (within 0.80 mm) to uninsulated live parts.
High-Definition Multimedia Interface
A compact audio visual interface for transmitting uncompressed digital data.
Higher Heating Value
The standard measure of the energy released during combustion of a fuel, assuming the product water is in the liquid state.
Highest Useful Compression Ratio
The highest compression upto which no knocking occurs in a given engine.
High-Field Emission
The discharge of electrons from the surface of a material subjected to a strong electric field.
High-Intensity Gamma
A level a gamma radiation flux on the order of 10E4 roentgens or higher.
Highway Fuel Economy Driving Schedule
One of the two EPA fuel economy tests, which consists driving routines, or schedules, performed in the laboratory.
High-Wing Monoplane
An aircraft which has its single wing mounted high on the fuselage.
A type of mechanical bearing formed between two parts allowing one to be rotated relative to the other e.g. door hinges.
A Greek astronomer who carried out his observations at Rhodes.
He believed that "the four fluids or humours of the body (blood, phlegm, yellow bile and black bile) are the primary seats of disease."
A graphical display showing the distribution of data values in a sample by dividing the range of the data into non-overlapping intervals and counting the number of values which fall into each interval.
Lists all History topics in the Encyclopaedia
Hits Per Scan
The number of times an RF beam strikes a target per antenna revolution.