| Fahrenheit: A temperature scale defined by 32? at the ice point and 212? at the boiling point of water at sea level.
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| Fail Safe: Any system that cannot fail in any mode without providing a directly observable indication of failure. Consider an electrical relay with a set of contacts that are open when it is un-powered. If a power source and a light bulb are connected in series with the contacts, the lamp will glow when the relay is energized. If the goal of this system is to insure that the relay has power, then this system is said to be fail safe. If the lamp, relay contacts, lamp power source relay coil, or the relay coil power supply fail, then the lamp extinguishes itself providing a directly observable foolproof indication of failure.
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| Fail-safe Operation: A feature designed to alert the operator via display, and to bring a process to a safe shutdown via output, in the event of a particular control system or process failure. |
| False Color: Color which is added to an image in order to accentuate details that aren?t readily perceptible. |
| FAQ -- (Frequently Asked Questions): FAQs are documents that list and answer the most common questions on a particular subject. There are hundreds of FAQs on subjects as diverse as Pet Grooming and Cryptography. FAQs are usually written by people who have tired of answering the same question over and over. |
| Far Field: A measurement distance sufficiently large (typically greater than 10 times the focal distance) whereby the spot size of an instrument is growing in direct proportion to the distance from the instrument, and the field of view is constant.
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| Faraday Cage: The name given to a device that shields its inside from electric fields generated by static electricity. Usually a complete conductive shell, it collects stray charges and, because like charges repel, stores them on the outside surface (where they can be further apart than on the inside). The electric fields generated by these charges then cancel each other out on the inside of the cage. Often used to protect sensitive radio equipment. |
| Fast Reactor: A reactor that is designed to use fast neutrons for sustaining the nuclear chain reaction. Fast reactors can be used to produce more fissile material than they consume. |
| FDDI -- (Fiber Distributed Data Interfac A standard for transmitting data on optical fiber cables at a rate of around 100,000,000 bits-per-second (10 times as fast as 10-BaseTEthernet, about twice as fast as T-3). |
| Ferromagnetism: Spontaneous alignment of magnetic dipoles within a material under the influence of a magnetic field, resulting in a hysteresis loop when the direction of magnetic field is switched.
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| Ferrule: A compressible tubular fitting that is compressed onto a probe inside a compression fitting to form a gas-tight seal.
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| FFT: Fast Fourier Transform. A computationally efficient mathematical technique which converts digital information from the time domain to the frequency domain for rapid spectral analysis.
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| Fiber Optics: A transmission medium consisting of thin strands of glass or plastic through which data is sent by means of pulse modulated light waves.
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| Fick`s First Law: An equation describing the rate at which a gas transfers into solution. The change in concentration of gas in solution is proportional to the product of an overall mass transfer coefficient and the concentration gradient. |
| Fick`s Second Law: An equation relating the change of concentration with time due to diffusion to the change in concentration gradient with distance from the source of concentration. |
| Field of View (FOV): The area or solid angle viewed through an optical or infrared instrument. Typically expressed by giving the spot diameter of an instrument and the
distance to that spot. Also expressed as the angular size of the spot at the focal point. See Optical or Infrared Resolution. |
| Field of View: A volume in space defined by an angular cone extending from the focal plane of an instrument. |
| FIFO Memory: A type of memory with separate input and output ports. The first data to enter the input port are the first to exit the output port.
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| FIIM : Federation International de l?Industrie du Medicament (International Federation of Pharmaceutical Manufacturer?s Association)
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| File: A set of related records or data treated as a unit.
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| Filling Solution: A solution of defined composition to make contact between an internal element and a membrane or sample. The solution sealed inside a pH glass bulb is called an internal filling solution. This solution normally contains a buffered chloride solution to provide a stable potential and a designated zero potential point. The solution which surrounds the reference electrode internal and periodically requires replenishing is called the reference filling solution. It provides contact between the reference electrode internal and sample through a junction.
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| Filter: An electrical circuit that passes frequencies within a specified frequency band and attenuates signals that fall outside of that frequency band.
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| Finger: An Internet software tool for locating people on other Internet sites. Finger is also sometimes used to give access to non-personal information, but the most common use is to see if a person has an account at a particular Internet site. Many sites do not allow incoming Finger requests, but many do. |
| Fire Wall: A combination of hardware and software that separates a Network into two or more parts for security purposes. |
| Fire Wire IEEE 1394: High Speed Serial data transmission which transmits up to 400Mbps. |
| Firmware : Software that is embedded in a hardware device that allows reading and executing the software, but does not allow modification, e.g., writing or deleting data by an end user.
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| Firmware: Software instructions stored in ROMs.
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| Fissile Material: A material consisting of atoms whose nuclei can be split when irradiated with low energy (ideally, zero energy) neutrons. Well-known examples are plutonium-239 and uranium-235.
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| Fission Product: Any isotope created by the fission of a heavy element. Fission products are usually radioactive.
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| Fission: The splitting of the nucleus of an element into fragments. Heavy elements such as uranium or plutonium release energy when fissioned.
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| Fixed-Point Processor: Used in multiple calculations with a limited dynamic range. |
| Flag: Any of various types of indicators used for identification of a condition or event; for example, a character that signals the termination of a transmission.
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| Flammability Range Flammable gases/vapors have limits below, and above, which flame propagation does not occur. The volume below which flame propagation does not occur is called the Lower Explosive (or Flammable) Limit (LEL). Below this concentration the mixture is said to be too 'lean' for a flame to propagate. The volume of gas/vapor in air above which a flame does not propagate is called the Upper Explosive Limit (UEL) |
| Flashpoint: Flashpoint is the minimum temperature at which a liquid gives off a sufficient vapor to reach 100% LEL (sufficient vapor to form an ignitable mixture with the air near the surface of the liquid). |
| Flavour: The name used for the different quarks types (up, down, strange, charm, bottom, top) and for the different lepton types (electron, muon, tau). For each charged lepton flavour there is a corresponding neutrino flavour. In other words, flavour is the quantum number that distinguishes the different quark/lepton types. Each flavour of quark and charged lepton has a different mass. For neutrinos we do not yet know if they have a mass or what the masses are. |
| Floating-Point Operations Per Second (FL A measurement of performance of capability assigned to a floating-point processor. It is usually noted as MFLOPS or Million FLOPS. |
| Floating-Point Processor: DUsed in multiple calculations to obtain high precision with an unlimited dynamic range |
| Flocculation: Gentle stirring or agitation to accelerate the agglomeration of particles to enhance sedimentation or flotation.
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| Floppy Disk: A small, flexible disk carrying a magnetic medium in which digital data is stored for later retrieval and use.
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| Flow Rate: Actual speed or velocity of fluid movement .
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| Flow Tube: A calibrated flow measuring device made for a specific range of flow velocities and fluids |
| Flow: Travel of liquids or gases in response to a force (i.e. pressure or gravity).
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| Flowmeter: A device used for measuring the flow or quantity of a moving fluid.
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| Flush Diaphragm: Sensing element is located on the very tip of the transducer (NO pressure port).
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| Flux : A chemically- or physically-active formulation which has the ability to clean oxides and enables wetting of metals with solder.
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| FM Approved: An instrument that meets a specific set of specifications established by Factory Mutual Research Corporation.
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| FM: Factory Mutual Research Corporation. An organization which sets industrial safety standards.
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| Focal Length: Distance from the focal point to the center of a lens or vertex of a mirror.
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| Focal Point or Distance: The point or distance from the instrument at which the object is focused onto the detector within the instrument. The focal point is the place or distance at which the optical or infrared resolution is greatest. |
| Focal Point: The focal point of a lens is defined by considering a narrow beam of light incident upon the lens, parallel to the optic (symmetry) axis of the lens and centered on that axis. The focal point is that point to which the rays converge or from which they diverge after passing through the lens. The convergent case defines a converging (positive) lens. The second case defines a diverging (negative) lens. It?s easy to tell which kind of lens you have, for converging lenses are thicker at their center than at the edges, and diverging lenses are thinner at the center than at the edges. |
| Forced Vibration: Vibration of a system caused by an imposed force. Steady-state vibration is an unchanging condition of periodic or random motion.
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| Four-Terminal Resistance Measurement: A measurement where two leads are used to supply current to the unknown and two different leads are used to sense the voltage drop across the resistance. |
| FPM: Flow velocity in feet per minute.
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| FPS: Flow velocity in feet per second.
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| Free Energy: A thermodynamic quantity that is a function of both the internal energy and entropy (or randomness) of a system; at equilibrium the free energy is at a minimum.
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| Freezing Point: The temperature at which the substance goes from the liquid phase to the solid phase.
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| Frequency Output: An output in the form of frequency which varies as a function of the applied input.
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| Frequency Response: The range of frequencies over which the transducer voltage output will follow the sinusoidally varying mechanical input within specified limits.
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| Frequency, Natural: The frequency of free (not forced) oscillations of the sensing element of a fully assembled transducer.
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| Frequency: The number of cycles over a specified time period over which an event occurs. The reciprocal is called the period.
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| Fresnel Reflection Losses: reflection losses due to the differences in refraction index between the core glass and immersion medium. The losses typically occur at the input and output of the optical fibers. |
| Friable: Easily crumbled, not cohesive or sticky.
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| FTP -- (File Transfer Protocol) A very common method of moving files between two Internet sites.
FTP is a way to login to another Internet site for the purposes of retrieving and/or sending files. There are many Internet sites that have established publicly accessible repositories of material that can be obtained using FTP, by logging in using the account name "anonymous", thus these sites are called "anonymous ftp servers".
FTP was invented and in wide use long before the advent of the World Wide Web and originally was always used from a text-only interface.
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| Full Bridge: A Wheatstone bridge configuration utilizing four active elements or strain gages.
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| Full Duplex: Communications that takes place in both directions at the same time.
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| Full Range Output: The span of electrical output between the maximum positive and the maximum negative end points of the calibration curve. |
| Full Scale Output: The algebraic difference between the minimum output (normally zero) and the rated capacity. |
| Functions: Three mode PID controller. A time proportioning controller with integral and derivative functions. The integral function automatically adjusts the system temperature to the set point temperature to eliminate droop due to the time proportioning function.
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| Fundamental Particle: A particle with no internal substructure. In the Standard Model the quarks, leptons, photons, gluons, W+ and W- bosons, and the Z bosons are fundamental. All other objects are made from these. |
| Fungi: Aerobic, multicellular, nonphotosynthetic, heterotrophic microorganisms. The fungi include mushrooms, yeast, molds, and smuts. Most fungi are saprophytes, obtaining their nourishment from dead organic matter. Along with bacteria, fungi are the principal organisms responsible for the decomposition of carbon in the biosphere. |
| Fusion: The combining of two nuclei to form a heavier one. Fusion of the isotopesof light elements such as hydrogen or lithium gives a large relsease of energy. |
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