# Se

Se
The electrical properties of selenium are of particular interest as it is both photovoltaic and photoconductive.
SEA
Abbreviation of Statistical Energy Analysis.
Sea Clutter
Unwanted echoes, from surrounding sea, that appear on a radar indicator.
SEA Coupling Loss Factors
Statistical energy analysis coupling between different types of structure.
Sea Water
Contains the majority of the common elements in small quantities.
Seaborg, Glenn
American nuclear chemist.
Seal
A device designed to prevent the movement of fluid from one area to another, or to exclude contaminants.
Seal Assembly
Assembly that includes sealing surfaces, provision for initial loading and a mechanism that accommodates the radial and axial movement necessary for installation and operation.
Seal Chamber
The area between the seal chamber bore and a shaft in which a mechanical seal is installed.
Seal Face
Either of the two surfaces in a mechanical seal assembly forming the primary seal.
Sealed Battery
A battery which can be operated without regard to position.
Seal-in Relay
An auxiliary relay that remains picked up through one of its own contacts, which bypasses the initiating circuit until de-energized by some other device.
Sealing Wax
The wax used to seal confidential documents.
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Sec
Abbreviation of trigonometric function secant.
Secant
Trigonometric function.
Secant Line
A line that intersects a curve or circle in two places.
Secant Modulus of Elasticity
Ratio of stress to strain at any point on curve in a stress-strain diagram.
Second
The second is the SI unit of time or 1/360 of a degree.
Second Class Lever
The load is situated between the fulcrum and the applied force.
Second Derivative
The derivative that comes after the first derivative and before the third derivative. Obtained by taking the derivative of a function twice in a row.
Second Ionization Energy
The energy needed to remove an electron from an isolated +1 ion.
Second Law of Thermodynamics
Clausius states: No process is possible whose sole result is the transfer of heat from a colder to a hotter body.
Second Order Reaction
A reaction with a rate law that is proportional to either the concentration of a reactant squared, or the product of concentrations of two reactants.
Second Postulate of Special Relativity
The speed of light in a vacuum is a constant regardless of the speed of the source or the speed of the observer.
Secondary Alignment
The act of measuring off-line to on-line machinery movement.
Secondary Cell
A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electric current though the cell in the opposite direction to that of discharge.
Secondary Coil
The output coil of a transformer
Secondary Electron
Produced by an incident electron passing near an atom in the specimen, near enough to impart some of its energy to a lower energy electron, usually in the K-shell.
Secondary Electron Imaging
Production of secondary electrons is very topography related. Any changes in topography in the sample that are larger than this sampling depth will change the yield of secondaries due to collection efficiencies.
Secondary Emission
Electron emission from a non-heated electrode when struck by a high-velocity electron beam.
Secondary Energy Source
An energy source such as electricity that is made using a primary energy source.
Secondary Metabolism
Pathways that lead to specialized products, not found in every living cell.
Secondary Radiation
Electromagnetic or particulate radiation resulting from absorption of other radiation in matter.
Secondary Ride
A term used to indicate the ride response of a vehicle in the frequency range of 8-20 Hz.
Sector
A non-overlapping piece of an object.
Sedimentation
Separation of a dense material from a less dense material by allowing the denser material to settle out of the mixture.
Seebeck Effect
The principle that describes how a thermocouple works.
Seiche
An oscillation of a fluid body in response to a disturbing force having the same frequency as the natural frequency of the fluid system.
Seismic
Of or having to do with earthquakes.
Seismograph
An instrument for detecting and recording the intensity, direction, and duration of a movement of the ground caused by an earthquake or explosion.
Seizure
Welding between surfaces in relative motion that results in immobilization of the parts.
SEL
There are a number of different noise criteria measurements used by local authorities to determine noise levels in the community.
Selected Area Electron Diffraction
An aperture is used to define the area from which a diffraction pattern is formed in a TEM specimen.
Selectivity
The ability of a receiver to select the desired signal and reject unwanted signals.
Selenium
The electrical properties of selenium are of particular interest as it is both photovoltaic and photoconductive.
Selenoid
A satellite of the earth′s moon, no such satellites are known.
Selenology
That branch of astronomy that treats of the moon.
Self Bias
In a vacuum tube circuit, the voltage developed by the flow of current through a resistor in the grid or cathode leads.
Self Discharge
The loss of useful capacity of a cell or battery due to internal chemical action.
Self Excited Generators
DC generators in which the generator output is fed to the field to produce field excitation.
Self Excited Meter
A term used to describe meters that operate from their own power sources.
Self Extinguishing
A material which will not support combustion when external source of flame is removed.
Self Induction
The production of a counter electromotive force in a conductor when its own magnetic field collapses or expands with a change in current in the conductor.
Self Noise
Extraneous non-acoustical signals, generated or induced in a measurement system.
Self Similarity
Two or more objects having the same characteristics.
Self Tapping Screw
A self-drilling fastener that drills its own hole, taps a mating thread, and then fastens, all in a single operation.
Self-Aligning Bearing
A roller-element bearing with one spherical raceway that automatically provides compensation for shaft or housing deflection or misalignment.
SEM
Abbreviation of Scanning Electron Microscope.
Semi Diesel Engine
A term applied to oil engines using rather low compression pressures and requiring a hot surface for ignition of the injected fuel.
Semi-Anechoic Chamber
A room which creates free field conditions but above a reflective plane.
Semicircular Canals
The three sensory organs for balance that are a part of the cochlear structure.
Semiconductor
An element, such as silicon, that is intermediate in electrical conductivity between conductors and insulators, through which conduction takes place by means of holes and electrons.
Semiconductor Detector
Radiation striking very pure Ge and Si semiconductor detectors can excite a large number of electrons into the conduction band leading to a measurable current.
Semiconductors
Lists all Semiconductors topics in the Encyclopaedia
Semiconductors Books
Lists all Semiconductors Books in the Encyclopaedia
Semiconductors Calculations
Lists all Semiconductors Calculations in the Encyclopaedia
Semiconductors Conversions
Lists all Semiconductors Conversions in the Encyclopaedia
Semiconductors Source Code
Lists all Semiconductors Source Code in the Encyclopaedia
Semiconductors Weblinks
Lists all Semiconductors Weblinks in the Encyclopaedia
Semicrystalline
Also known as Polycrystalline.
Semi-Magic Square
A square array of n numbers such that sum of the n numbers in any row or column is a constant (known as the magic sum).
Semi-Metal
An element with both metallic and nonmetallic properties e.g. silicon.
Semi-Permeable Membrane
A membrane that allows some but not all of the components in a mixture to pass through it.
Semitone
An interval equal to a half tone in the standard diatonic scale.
Sensation Level
The level of psychophysiologic stimulation above the threshold.
Sensible Energy
The internal energy of a system associated with kinetic energies (molecular translation, rotation, and vibration; electron translation and spin; and nuclear spin) of the molecules.
Sensitivity
The greater the sensitivity, the greater the system′s signal-to-noise ratio.
Sensitivity Time Control
A circuit that varies the gain of a receiver as a function of time.
Sensor
A device that converts a physical stimulus (such as force, sound, pressure, motion) into a corresponding electrical signal.
Sensor-Neural Hearing Loss
Hearing loss originating in the cochlea or the fibres of the auditory nerve.
Sensory Pleasantness
An acoustic metric derived by Zwicker this is a combination of loudness, roughness, sharpness and tonality these are all expressed as relative values making sensory pleasantness a relative quantity.
Separable Equations
A differential equation is separable if it can be written: y′=A(x)B(y)
Septagon
A seven-sided polygon.
Septet
A unit of quantity equal to 7.
Septillion
A number equal to 1024.
Septum
The muscular wall that separates the left and right sides of the heart.
Sequence
An ordered set whose elements are usually determined based on some function of the counting numbers.
Sequential Access Memory
A memory in which access of the registers must be in sequential order.
Serial Communications
Transmission of binary data from one device to another one bit at a time.
Serial InfraRed
Wireless communication system for PCs and peripherals.
Series
The sum of a finite or infinite sequence.
Series Circuit
An arrangement where electrical devices are connected so that the total current must flow through all the devices; electrons have one path to travel from the negative terminal to the positive terminal.
Series Diode Detector
The semiconductor diode in series with the input voltage and the load impedance.
Series Expansions
Most functions can be described as an series expansion.
Series Fed Oscillator
An oscillator in which dc power is supplied to the amplifier through the tank circuit or a portion of the tank circuit.
Series Limiter
A diode connected in series with the output, in which the output is taken across the resistor.
Series Parallel Circuit
A circuit that consists of both series and parallel networks.
Series Peaking
A technique used to improve high-frequency response in which a peaking coil is placed in series with the output signal path.
Series Resonant Circuit
A resonant circuit in which the source voltage is connected in series with a capacitor and an inductor to furnish a low impedance at the frequency at which the circuit is resonant.
Series Voltage Regulator
A regulator with a regulating device that is in series with the load resistance.
Series Wound Motor and Generator
Electric motor in which the armature and field windings are connected in series with each other.
Service Ceiling
Normally height at which an aircraft can maintain a maximum rate of climb of 100 ft/minute.
Service Drag
This is drag from air ducted to cooling components.
Service Life
The length of time a part can be used in a given application.
Servo Amplifier
Either ac or dc amplifiers used in servosystems to build up signal strength.
Servo Motor
An ac or dc motor used in servo systems to move a load to a desired position or at a desired speed.
Servo System
An automatic feedback control system that compares a required condition with an actual condition and uses the difference to drive a control device to achieve the required condition.
Sesquioxide
An oxide containing three atoms of oxygen with two atoms of another element.
Set
A collection of objects called elements.
Set Point
Value of a controlled variable, departure from which causes a controller to operate to reduce the error and restore the intended steady state.
Set Screw
A plain screw used principally for locking adjustable parts in position.
Settling Time
When a change in a signal occurs, this is the time taken for it to settle to its new value.
Sexadecimal
The same as Hexadecimal.
Sexagesimal
In the sexagesimal system calculations are done in the base 60 as used by the Ancient Babylonians.
Sextet
A unit of quantity equal to 6.
Sextillion
A number equal to 1021.
Sextuple
A group of six items.
Seyfert Galaxy
Type of galaxy with a point-like nucleus and very faint spiral arms, first described in 1943 by American astrophysicist Carl Seyfert.