| C I P: Chemical Injection Pump, relates to metering pumps with a varibal output at a given pressure. |
| Cable Telephony: The practice of using digital communications techniques to provide enhanced home telephone service via the existing home cable-TV connections.
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| Cache: A temporary storage area for frequently-accessed or recently-accessed data. Having certain data stored in a cache speeds up the operation of the computer. There are two kinds of cache: internal (or memory cache) and external (or disk cache). Internal cache is built into the processor, and external cache is on the motherboard. When an item is called for, the computer first checks the internal cache, then the external cache, and finally the slower main storage.
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| CAD: Computer Aided Design. |
| CAE: Computer Aided Engineering. |
| Calcium Carbonate (CACO3 ) Equivalent: An expression of the concentration of specified constituents in water in terms of their equivalent value to calcium carbonate. For example, the hardness in water which is caused by calcium, magnesium and other ions is usually described as calcium carbonate equivalent |
| Calender-Van Dusen Equation: An equation that defines the resistance-temperature value of any pure metal that takes the form of RT = RO(1 + AT + BT2) for values between the ice point (0?C) and the freezing point of antimony (630.7?C) and the form RT = RO[1 + AT + BT2 + C(T-100)T2] between the oxygen point (-183.0?C) and the ice point (0?C). |
| Calibration Procedure: A procedure that is performed to determine and set the parameters affecting an instrument?s performance in order to ensure its designed function within prescribed limits. |
| Calibration Source: A source for which the radiance temperature can be calibrated to within a known level of uncertainty in relation to some other parameter, and in which this relationship is sufficiently constant to enable it to be used for a reasonable period without calibration. |
| Calibration: The comparison of transducer voltage outputs against the outputs of a reference standard.
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| Calorie: The quantity of thermal energy required to raise one gram of water 1?C at 15?C. |
| CAM: Computer Aided Manufacturing. |
| Canadian Standards Association (CSA): An organization that provides testing and certification services for manufacturers that wish to use the CSA mark on products that conform to the appropriate CSA standard.
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| Candela: Unit of luminous intensity
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| Capacity: This word is used in names of quantities which express the relative amount of some quantity with respect to a another quantity upon which it depends. For example, heat capacity is dU/dT, where U is the internal energy and T is the temperature. Electrical capacity, or capacitance is another example: C = |dQ/dV|, where Q is the magnitude of charge on each capacitor plate and V is the potential diference between the plates.
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| Capillary Action: The movement of water through very small spaces due to molecular forces |
| Capillary Fringe: The porous material just above the water table which may hold water by capillarity (a property of surface tension that draws water upwards) in the smaller void spaces |
| Capillary Suction: The process whereby water rises above the water table into the void spaces of a soil due to tension between the water and soil particles.
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| Capillary Tube: A restrictive tube used in a refrigeration system which restricts the flow of freon and allows pressure to build on one side and suction on the other. It is located between the condenser and the evaporator. |
| Carnot Cycle: An ideal heat engine that converts thermal energy to mechanical work with the greatest efficiency that can be achieved. |
| Carrier System: A method of obtaining communications channels over a single communications link by multiplexing the channels together at the transmitting end and demultiplexing them at the receiving end.
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| CAS Registration Number: A number assigned by the Chemical Abstracts Service to identify a chemical |
| Catalyst: A substance that changes the speed or yield of a chemical reaction without being consumed or chemically changed by the chemical reaction |
| Cathode: The negative pole or electrode of an electrolytic cell or system. The cathode attracts positively charged particles or ions (cations). |
| Cathodic Protection: An electrical system for prevention of rust, corrosion, and pitting of metal surfaces which are in contact with water or soil. A low- voltage current is made to flow through a liquid (water) or a soil in contact with the metal in such a manner that the external electromotive force renders the metal structure cathodic. This concentrates corrosion on auxiliary anodic parts which are deliberately allowed to corrode instead of letting the structure corrode. |
| Cation: A positively charged ion (Na+, H+). |
| CATP: (Caffeine Access Transport Protocol) Common method of moving caffeine across Wide Area Networks such as the Internet. CATP was first used at the Binary Cafe in Cybertown and quickly spread world-wide. There are reported problems with short-circuits and rust and decaffinated beverages were not supprted until version 1.5.3 |
| Cavitation: The boiling of a liquid caused by a decrease in pressure rather than an increase in temperature. |
| CDMA: Code Division Multiple Access. Also known as spread spectrum, allowing several users to share a channel by allocating "codes" that allow each one to distinguish between them, even though they use the same frequency bands at the same time.
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| CECC: Cenelec Electronic Components Committee.
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| Cell: An ATM packet that is 53 bytes in length with a 5 byte header and 48 byte payload. |
| Celsius (Centigrade): A temperature scale defined by 0?C at the ice point and 100?C at boiling point of water at sea level. |
| Center of Gravity (Mass Center): The center of gravity of a body is that point in the body through which passes the resultant of weights of its component particles for all orientations of the body with respect to a uniform gravitational field.
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| Centrifugal Compressor: A machine in which air or gas is compressed by the mechanical action of rotating vanes or impellers imparting velocity and pressure to the air or gas. In a centrifugal compressor, flow is in a radial direction. Air enters the compressor through the machine mounted inlet control valve and flows to the first stage where the impeller imparts velocity energy to the air. The air then proceeds through a diffuser section which converts the velocity energy to pressure energy. |
| Centrifuge: A mechanical device that uses centrifugal or rotational forces to separate solids from liquids. |
| Centripetal Force: A force exerted on an object moving in a circular path which is exerted inward toward the center of rotation.
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| Ceramic Insulation: High-temperature compositions of metal oxides used to insulate a pair of thermocouple wires The most common are Alumina (Al2O3), Beryllia (BeO), and Magnesia (MgO). Their application depends upon temperature and type of thermocouple. High-purity alumina is required for platinum alloy thermocouples. Ceramic insulators are available as single and multihole tubes or as beads. |
| Ceramic: Polycrystalline ferroelectric materials which are used as the sensing units in piezoelectric accelerometers. There are many different grades, all of which can be made in various configurations to satisfy different design requirements.
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| Cermet: Resistive element made from a mixture of glass and metal oxides.
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| Certificate Authority: An issuer of Security Certificates used in SSL connections. |
| CFM: The volumetric flow rate of a liquid or gas in cubic feet per minute.
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| CGI -- (Common Gateway Interface): A set of rules that describe how a Web Server communicates with another piece of software on the same machine, and how the other piece of software (the ?CGI program?) talks to the web server. Any piece of software can be a CGI program if it handles input and output according to the CGI standard. |
| CGS: The system of units based upon the fundamental metric units: centimeter, gram and second.
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| Character: A letter, digit or other symbol that is used as the representation of data. A connected sequence of characters is called a character string.
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| Charge Amplifier: Electronic unit which utilizes a high-gain voltage amplifier with negative, capacitive feedback for converting a charge from a piezoelectric transducer into a low impedance output voltage.
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| Charge Sensitivity: For accelerometers that are rated in terms of charge sensitivity, the output voltage (V)is proportional to the charge (Q) divided by the shunt capacitance (C). This type of accelerometer is characterized by a high output impedance. The sensitivity is given in terms of charge; picocoulombs per unit of acceleration (g).
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| Charm Quark (c): The fourth quark (in order of increasing mass), with electric charge +2/3. |
| Charpy Test: A pendulum-type single-blow impact test in which the specimen usually notched, is supported at both ends as a simple beam and broken by a falling pendulum. The energy absorbed, as determined by the subsequent rise of the pendulum, is a measure of impact strength or notch toughness. |
| Chatter: The rapid cycling on and off of a relay in a control process due to insufficient bandwidth in the controller.
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| Check Sum: A number, determined by adding up all the data in a file, used to identify its contents. Often only some (4) of the least significant digits (those on the right side) are recorded as they are the ones most likely to change if the data changes.
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| Check Valve: A valve that permits flow in one direction only.
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| Checksum: A block check character that is formed by taking the sum of the binary data transmitted.
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| Chelation: (key-LAY-shun). A chemical complexing (form- ing or joining together) of metallic cations (such as copper) with certain organic compounds, such as EDTA (ethylene diamine tetracetic acid). Chelation is used to prevent the precipitation of metals (copper). Also see sequestration. |
| Chemical Oxygen Demand (COD): An indirect measure of the amount of oxygen used by inorganic and organic matter in water. The measure is a laboratory test based on a chemical oxidant and therefore does not necessarily correlate with biochemical oxygen demand. |
| Childseat Presence Orientation Detection Pressure sensitive foil with integrated antenna and resonators in the childseat to keep the airbag from firing with full capacity if necessary.
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| Chloramines: Compounds formed by the reaction of hypochlorous acid (or aqueous chlorine) with ammonia. |
| Chlorination: The application of chlorine to water, generally for the purpose of disinfection, but frequently for accomplishing other biological or chemical results (aiding coagulation and controlling tastes and odors). |
| Chlorinator: A metering device which is used to add chlorine to water. |
| Chlorine Demand: Chlorine demand is the difference between the amount of chlorine added to water and the amount of residual chlorine remaining after a given contact time. Chlorine demand may change with dosage, time, temperature, pH, and nature and amount of the impurities in the water. Chlorine Demand, mg/L = Chlorine Applied, mg/L - Residual, mg/L |
| Chlorine Requirement: The amount of chlorine which is needed for a particular purpose. Some reasons for adding chlorine are reducing the number of coliform bacteria (Most Probable Number), obtaining a particular chlorine residual, or oxidizing some substance in the water. In each case a definite dosage of chlorine will be necessary. This dosage is the chlorine requirement |
| Chlorine-Contact Chamber: That part of a water treatment plant where effluent is disinfected by chlorine. |
| Chromatic Aberration: Variation in focal length of lens with wavelength of light. |
| Chrominance: That part of a video signal which is responsible for the hue and saturation of the signal, but not the luminance or brightness. |
| Chronic Exposure: Long-term, low-level exposure to a toxic chemical. |
| Circuit Switching: A method of establishing a dedicated communications path between two or more locations through one or more switching nodes. Data is sent in a continuous stream; the data rate is constant; the delay is constant and limited to propagation times; and a dedicated end to end path remains in effect until the communication is terminated.
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| Circular Buffer: A section of internal memory that can be represented as circular in nature where a software pointer is used to point to the incoming sample values. Following samples will be put in the next section (block) of memory around the circle. After the last sample corresponding to the last memory location is received, the next sample starts at the beginning of the buffer. A circular buffer ensures that the data is processed in a FIFO (first in first out) manner. |
| Cladding: A material which has a lower index of refraction than the core of an optical waveguide, which surrounds the waveguide, keeping the light in the core. |
| Class 2 Circuit: An isolated secondary circuit involving not more than 42.2V (peak) with specific current level limitations.
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| Clear: To restore a device to a prescribed initial state, usually the zero state.
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| Client-Server Network: A network that uses a central computer (server) to store data that is accessed from other computers on the network (clients).
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| Clipping: The term applied to the phenomenon which occurs when an output signal is limited in some way by the full range of an amplifier, ADC or other device. When this occurs, the signal is flattened at the peak values, the signal approaches the shape of a square wave, and high frequency components are introduced. Clipping may be hard, as is the case when the signal is strictly limited at some level; or it may be soft, in which case the clipping signal continues to follow the input at some reduced gain.
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| Clock: The device that generates periodic signals for synchronization.
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| Closeness of Control: Total temperature variation from a desired set point of system. Expressed as "closeness of control" is ?2?C or a system bandwidth with 4?C, also referred to as amplitude of deviation.
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| CMR (Common-Mode Rejection): The ability of a panel meter to eliminate the effect of AC or DC noise between signal and ground. Normally expressed in dB at dc to 60 Hz. One type of CMR is specified between SIG LO and PWR GND. In differential meters, a second type of CMR is specified between SIG LO and ANA GND (METER GND). |
| CMV (Common-Mode Voltage): The AC or DC voltage which is tolerable between signal and ground. One type of CMV is specified between SIG LO and PWR GND. In differential meters, a second type of CMV is specified between SIG HI or LO and ANA GND (METER GND).
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| CNG: ACRONYM - Compressed natural gas, primarily methane. |
| Coagulation: The clumping together of very fine particles into larger particles caused by the use of chemicals (coagulants). The chemicals neutralize the electrical charges of the fine particles and cause destabilization of the particles. This clumping together makes it easier to separate the solids from the water by settling, skimming, draining, or filtering. |
| Coalescing Filter: A filter unit that combines three principles to filter out oil aerosols: 1) Direct interception - A sieving action, 2) Inertial impaction - Collision with filter media fibers, 3) Diffusion -Particles travel in a spiral motion, presenting an effective frontal area thus capturing particles within the filter medium. |
| Coaxial Cable: A tubular wire transmission medium that consists of a central conductor surrounded by a dielectric insulator tht is in turn surrounded by a tubular conductor. The outer conductor is usually at ground potential and also serves as an electrical shield.
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| Codec: An abbreviation for Coder-Decoder. An analog-to-digital (A/D) and digital-to-analog (D/A) converter for translating the signals from the outside world to digital, and back again.
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| Coefficient of Friction: Ration of frictional force and the normal force between two surfaces.
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| Coherence Function.: A frequency domain function computed to show the degree of a linear, noise-free relationship between a system?s input and output. The value of the coherence function ranges between zero and one, where a value of zero indicates there is no causal relationship between the input and the output. A value of one indicates the existence of linear noise-free frequency response between the input and the output.
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| Cohesion: Molecular attraction which holds two particles together |
| Cold Working: Plastic deformation of a metal at a temperature below that at which it recrystallizes; increasing the amount of cold work causes the dislocation density to rise in the material, making it more difficult to plastically deform the material and eventually cause brittle fracture.
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| Collider: An accelerator in which two beams traveling in opposite directions are steered together to provide high-energy collisions between the particles in one beam and those in the other. |
| Colloids: Very small, finely divided solids (particles that do not dissolve) that remain dispersed in a liquid for a long time due to their small size and electrical charge. When most of the particles in water have a negative electrical charge, they tend to repel each other. This repulsion prevents the particles from clumping together, becoming heavier, and settling out. |
| Color Bars: The test pattern viewed on a display screen which is color saturated (red, green, blue, cyan, magenta, and yellow) plus black and white. |
| Color Code: The ANSI established color code for thermocouple wires in the negative lead is always red. Color Code for base metal thermocouples is yellow for Type K, black for Type J, purple for Type E and blue for Type T.
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| Color Temperature: The temperature of a black body from which the radiant energy has the same spectral distribution as that from a surface. |
| Colored Body or Non Gray Body A source of thermal emission for which the emissivity depends on wavelength and is not constant. |
| Colorimetric Measurement: A means of measuring unknown chemical concentrations in water by measuring a sample?s color intensity. The specific color of the sample, developed by addition of chemical reagents, is measured with a photoelectric colorimeter or is compared with "color standards" using, or corresponding with, known concentrations of the chemical |
| Combined Available Residual Chlorine: The concentration of residual chlorine which is combined with ammonia (NH3) and/or organic nitrogen in water as a chloramine (or other chloro derivative) yet is still available to oxidize organic matter and utilize its bactericidal properties. |
| Combined Residual Chlorination: The application of chlorine to water to produce combined available residual chlorine. This residual can be made up of monochloramines, dichloramines, and nitrogen trichloride. |
| Combustion The rapid oxidation of a substance involving heat and light. |
| Common Mode Rejection Ratio: The ability of an instrument to reject interference from a common voltage at its input terminals with relation to ground. Usually expressed in db (decibels).
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| Common Mode: The output form or type of control action used by a temperature controller to control temperature, i.e. on/off, time proportioning, PID.
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| Communications Port: A connection on a terminal through which data is input and/or output. |
| Comparison Pyrometry: Method of radiation thermometry wherein the temperature of a calibrated source is changed until the radiation received from the source is the same as that from the target to determine the temperature of the target. |
| Compensated Temperature Range: The range of temperature over which the thermal errors of the transducer have been compensated and to which specified values of thermal zero shift, thermal sensitivity shift, thermal zero repeatability, and thermal sensitivity repeatability apply.
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| Compensating Alloys: Alloys used to connect thermocouples to instrumentation. These alloys are selected to have similar thermal electric properties as the thermocouple alloys (however, only over a very limited temperature range).
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| Compensation: An addition of specific materials or devices to counteract a known error. |
| Compiler: A software tool used to translate higher-level languages (e.g., C, FORTRAN, COBOL) into machine-code instructions for a computer to execute.
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| Complex Function: Any mathematically defined relationship given by the following expression:
y(x) = a(x) + ib(x)
Where: x = the real variable
a(x) = the real part of y(x)
b(x) = the imaginary part of y(x)
Complex functions are usually expressed in terms of both their amplitude and phase. |
| Complex Wave: The resultant form of a number of sinusoidal waves that are summed together forming a periodic wave. Such waves may be analyzed in the frequency domain to readily determine their component parts |
| Compound: A substance composed of two or more elements whose composition is constant. For example, table salt (sodium chloride - NACl) is a compound |
| Compressed Air : Air under pressure greater than that of the atmosphere.
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| Compressibility Factor Z: Is the ratio of the actual volume of the gas to the volume determined according to the perfect gas law.
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| Compression Adiabatic: Compression in which no heat is transferred to or from the gas during the compression process |
| Compression Efficiency: Is the ratio of the theoretical work requirement to the actual work required to be performed on the gas for compression and delivery. |
| Compression Ratio: The ratio of the number of bits required to represent the original information to the number of bits required to represent the compressed signal.
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| Condensate: condensed material, e.g. liquid water or ice .
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| Conductance: The measure of the ability of a solution to carry an electrical current. (See Equivalent Conductance)
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| Conduction (Thermal): The transfer of heat energy through a material (solid, liquid, or gas) by the motion of adjacent atoms and molecules without gross displacement of the particles. |
| Conduction: The conveying of electrical energy or heat through or by means of a conductor.
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| Confidence Level: The range (with a specified value of uncertainty, usually expressed in percent) within which the true value of a measured quantity exists.
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| Confined Aquifer: An aquifer in which ground water is confined under pressure which is significantly greater than atmospheric pressure. |
| Conformal Coating : A coating that is applied to a completed circuit board the purpose of which is to inhibit the existence of corrosion and fungi.
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| Conformity Error: For thermocouples and RTDs, the difference between the actual reading and the temperature shown in published tables for a specific voltage input.
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| Connection Head: An enclosure attached to the end of a thermocouple which can be cast iron, aluminum or plastic within which the electrical connections are made.
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| Consonance: Two or more sounds that, when heard together, sound pleasant.
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| Constantan: A copper-nickel alloy used as the negative lead in Type E, Type J, and Type T thermocouples.
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| Consumables: Consumables are those materials or components which are depleted or require periodic replacement through normal use of the instrument. |
| Contention: A method of line control in which terminals compete with each other for permission to transmit over a common channel. If the channel is free, the terminal transmits. If the channel is in use by another terminal, the terminal attempting to transmit waits until the channel is free.
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| Control Character: A character whose occurrence in a particular context starts, modifies or stops an operation that effects the recording, processing, transmission or interpretation of data.
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| Control Mode: The output form or type of control action used by a temperature controller to control temperature, i.e., on/off, time proportioning, PID.
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| Control Point: The temperature at which a system is to be maintained.
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| Convection: Transmission of energy or mass in a medium by movement of the medium itself.
|
| Cookie The most common meaning of "Cookie" on the Internet refers to a piece of information sent by a Web Server to a Web Browser that the Browser software is expected to save and to send back to the Server whenever the browser makes additional requests from the Server.
Depending on the type of Cookie used, and the Browsers? settings, the Browser may accept or not accept the Cookie, and may save the Cookie for either a short time or a long time.
Cookies might contain information such as login or registration information, online "shopping cart" information, user preferences, etc.
When a Server receives a request from a Browser that includes a Cookie, the Server is able to use the information stored in the Cookie. For example, the Server might customize what is sent back to the user, or keep a log of particular users? requests.
Cookies are usually set to expire after a predetermined amount of time and are usually saved in memory until the Browser software is closed down, at which time they may be saved to disk if their "expire time" has not been reached.
Cookies do not read your hard drive and send your life story to the CIA, but they can be used to gather more information about a user than would be possible without them.
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| Coriolis Force: A result of centripetal force on a mass moving with a velocity radially outward in a rotating plane. |
| Cosmology: The study of the history of the universe. |
| Coulomb: A measurement of the quantity of electrical charge, usually expressed as pico coulomb (10-12 coulombs). |
| Counter Weight: A weight added to a body so as to reduce a calculated unbalance at a desired place.
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| Counts: The number of time intervals counted by the dual-slope A/D converter and displayed as the reading of the panel meter, before addition of the decimal point.
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| Covalent Bond: A primary interatomic bond that is formed by the sharing of electrons between neighboring atoms. |
| CPIP Carrier Pigeon Internet Protocol. A Norwegian system where data is converted to graphic form, flown by birds, and scanned at the other end. |
| CPU: Central processing unit. The part of the computer that contains the circuits that control and perform the execution of computer instructions.
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| Creep: The time-dependent permanent deformation that occurs under stress; for most materials it is important only at elevated temperatures.
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| Critical Damping : Critical damping is the smallest amount of damping at which a given system is able to respond to a step function without overshoot.
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| Critical Damping: Critical damping is the smallest amount of damping at which a given system is able to respond to a step function without overshoot.
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| Critical Mass: The amount of a fissile substance that will allow a self-sustaining chain reaction. The amount depends both on the properties of the fissile element and on the shape of the mass.
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| Critical Pressure: The pressure under which a substance may exist as a gas in equilibrium with the liquid at the critical temperature |
| Critical Speed: The rotational speed of the rotor or rotating element at which resonance occurs in the system. The shaft speed at which at least one of the "critical" or natural frequencies of a shaft is excited.
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| Critical Temperature: The temperature above which a gas cannot be liquified by pressure alone. |
| Cross Coupling : The coupling of a signal from one channel, circuit, or conductor to another, where it is usually considered to be an undesired signal.
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| Crosstalk: The unwanted transfer of energy from one communications circuit to another |
| Cryogenics: Measurement of temperature at extremely low values, i.e., below -200?C. |
| CSA: Canadian Standards Administration.
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| Cure Point: The temperature at which a normally magnetic material goes through a magnetic transformation and becomes non-magnetic.
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| Curie Temperature : The temperature above which a ferromagnetic or ferrimagnetic material becomes paramagnetic.
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| Current Proportioning: An output form of a temperature controller which provides a current proportional to the amount of control required. Normally is a 4 to 20 milliamp current proportioning band.
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| Current-Loop: A form of communications wherein a pair of wires is used to transmit the signal as a current. Levels of 4 to 20 mA are often used to indicate the minimum and maximum signal level, respectively. Sometimes, for digital applications, various magnitudes of mA current are used to indicate a logical 1 and 0. The current loop is often characterized by a maximum impedance of the device that is connected to the loop. |
| Current: The rate of flow of electricity. The unit of the ampere (A) defined as 1 ampere = 1 coulomb per second.
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| Curve Fitting: Curve fitting is the process of computing the coefficients of a function to approximate the values of a given data set within that function. The approximation is called a "fit". A mathematical function, such as a least squares regression, is used to judge the accuracy of the fit.
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| Cyberspace Term originated by author William Gibson in his novel Neuromancer the word Cyberspace is currently used to describe the whole range of information resources available through computer networks. |
| Cycle Time: The time usually expressed in seconds for a controller to complete one on/off cycle. |
| Cyclic Redundancy Check (CRC) : An error-detection scheme that (a) uses parity bits generated by polynomial encoding of digital signals, (b) appends those parity bits to the digital signal, and (c) uses decoding algorithms that detect errors in the received digital signal. |
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