eBook: Automating Manufacturing Systems; with PLCs


A.9 I

IAB (internet Activities Board) - the developer of internet standards.
IC (Integrated Circuit) - a microscopic circuit placed on a thin wafer of semiconductor.
IEC (International Electrical Commission) - A Swiss electrical standards group.
IEEE (Institute of Electrical and Electronics Engineers) -
IEEE802 - a set of standards for LANs and MANs.
IGES (Initial Graphics Exchange Specification) - a standard for moving data between various CAD systems. In particular the format can handle basic geometric entities, such as NURBS, but it is expected to be replaced by PDES/STEP in the near future.
impact instrument - measurements are made based by striking an object. This generally creates an impulse function.
impedance - In electrical systems this is both reactive and real resistance combined. This also applies to power transmission and flows in other types of systems.
impulse Noise - a short duration, high intensity noise. This type of noise is often associated with explosions.
increment - increase a numeric value.
inductance - current flowing through a coil will store energy in a magnetic field.
inductive heating - a metal part is placed inside a coil. A high frequency AC signal is passed through the coil and the resulting magnetic field melts the metal.
infrared - light that has a frequency below the visible spectrum.
inertia - a property where stored energy will keep something in motion unless there is energy added or released.
inference - to make a decision using indirect logic. For example if you are wearing shoes, we can infer that you had to put them on. Deduction is the complementary concept.
inference engine - the part of an expert system that processes rules and facts using forward or backward chaining.
Insertion Loss - barriers, hoods, enclosures, etc. can be placed between a sound source, and listener, their presence increases reverberant sound levels and decreases direct sound energy. The increase in the reverberant sound is the insertion loss.
instruction set - a list of all of the commands that available in a programmable system. This could be a list of PLC programming mnemonics, or a list of all of the commands in BASIC.
instrument - a device that will read values from external sensors or probes, and might make control decision.
intake stroke - in a piston cylinder arrangement this is the cycle where gas or liquid is drawn into the cylinder.
integral control - a control method that looks at the system error over a long period of time. These controllers are relatively immune to noise and reduce the steady state error, but the do not respond quickly.
integrate - to combine two components with clearly separable functions to obtain a new single component capable of more complex functions.
intelligence - systems will often be able to do simple reasoning or adapt. This can mimic some aspects of human intelligence. These techniques are known as artificial intelligence.
intelligent device - a device that contains some ability to control itself. This reduces the number of tasks that a main computer must perform. This is a form of distributed system.
interface - a connection between a computer and another electrical device, or the real world.
interlock - a device that will inhibit system operation until certain conditions are met. These are often required for safety on industrial equipment to protect workers.
intermittent noise - when sounds change level fluctuate significantly over a measurement time period.
internet - an ad-hoc collection of networks that has evolved over a number of years to now include millions of computers in every continent, and by now every country. This network will continue to be the defacto standard for personal users. (commentary: The information revolution has begun already, and the internet has played a role previously unheard of by overcoming censorship and misinformation, such as that of Intel about the Pentium bug, a military coup in Russia failed because they were not able to cut off the flow of information via the internet, the Tianneman square massacre and related events were widely reported via internet, etc. The last stage to a popular acceptance of the internet will be the World Wide Web accessed via Mosiac/Netscape.)
internet address - the unique identifier assigned to each machine on the internet. The address is a 32 bit binary identifier commonly described with the dotted decimal notation.
interlacing - is a technique for saving memory and time in displaying a raster image. Each pass alternately displays the odd and then the even raster lines. In order to save memory, the odd and even lines may also contain the same information.
interlock - a flag that ensures that concurrent streams of execution do not conflict, or that they cooperate.
interpreter - programs that are not converted to machine language, but slowly examined one instruction at a time as they are executed.
interrupt - a computer mechanism for temporarily stopping a program, and running another.
inverter - a logic gate that will reverse logic levels from TRUE to/from FALSE.
I/O (Input/Output) - a term describing anything that goes into or out of a computer.
IOR (Inclusive OR) - a normal OR that will be true when any of the inputs are true in any combinations. also see Exclusive OR (EOR).
ion - an atom, molecule or subatomic particle that has a positive or negative charge.
IP (internet Protocol) - the network layer (OSI model) definitions that allow internet use.
IP datagram - a standard unit of information on the internet.
ISDN (Integrated Services Digital Network) - a combined protocol to carry voice, data and video over 56KB lines.
ISO (International Standards Organization) - a group that develops international standards in a wide variety of areas.
isolation - electrically isolated systems have no direct connection between two halves of the isolating device. Sound isolation uses barriers to physically separate rooms.
isolation transformer - a transformer for isolating AC systems to reduce electrical noise.

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