See constellation.
Each year exactly divisible by 4 is a leap year, except century years (1800, 1900, etc.), which must be exactly divisible by 400 (2000, 2400, etc.) to be leap years. The calendar year is based on the tropical year. Also called civil year.
A unit of heat originally defined as the amount of heat required to raise the temperature of 1 gram of water through 1° C (the gram-calorie or small calorie).
Several calories are now in use: International Steam Table calorie = 4.1868 joules, mean calorie = 4.19002 joules, thermochemical calorie = 4.184 joules, 15° C calorie = 4.18580 joules, 20° C = 4.1890 joules. The kilogram calorie or kilocalorie is 1000 times as large as a calorie.
Calorimeters are used in some pyrheliometers.
See constellation.
See constellation.
The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 * 1012 hertz and that has a radiant intensity in that direction of (1/683) watt per steradian (16th CGPM (1979), Resolution 3).
The previous is an excerpt from WWW version of the National Institute of Standards and Technology: Physics Laboratory's International System of Units (SI)
Also called candle.
See constellation.
See constellation.
See constellation.
Capabilities belong to people, organized forces, or things.
See constellation.
2. A small, sealed, pressurized cabin with an internal environment which will support life in a man or animal during extremely high altitude flight, space flight, or emergency escape. See ejection capsule.
The term spacecraft is preferred to capsule for any man-carrying vehicle.
3. A container carried on a rocket or spacecraft, as an instrument capsule holding instruments intended to be recovered after a flight.
2. Acquisition or absorption of an additional particle by an atomic nucleus.
This cycle, first suggested by Bethe in 1938, gets its name from the fact that carbon plays the role of a kind of catalyst in that it is both used by and produced by the reaction, but is not consumed itself. Four protons are, in net, converted into an alpha particle and two positrons (with accompanying neutrinos); and three gamma-ray emissions are emitted directly in addition to the two gamma emissions that ensue from annihilation of the positrons by ambient electrons. This cycle sets in at stellar interior temperatures of the order of 5 million degrees Kelvin.
An even simpler reaction, the proton-proton reaction, is also believed to occur within the sun and may be of equal or greater importance.
Standard punched cards are 7.375 x 3.250 x 0.007 inches, containing either 80 columns in each of which any of 12 positions may be punched or 90 columns in each of which any combination of 6 places may be punched.
2. Any card adapted for the storage of information.
3. A printed-circuit board, usually before other parts are mounted therein. See module, package.
An automatic card punch punches cards according to a stored program.
In a Carnot cycle, the net work done is the difference between the heat inputQ1at higher temperatureT1and the heat extractedQ2at the lower temperatureT2.
2. In modulation of a signal, a wave suitable for being modulated as a sine wave, a recurring series of pulses, or a direct current.
A wave generated at a point in the transmitting system and modulated by the signal.
The three planes intersect in three straight lines, called coordinate axes. The coordinate planes and coordinate axes intersect in a common point, called the origin. From any point P in space three straight lines may be drawn, each of which is parallel to one of the three coordinate planes. If A, B, C denote these points of intersection, the Cartesian coordinates of P are the distances PA, PB, and PC. If the coordinate axes are mutually perpendicular, the coordinate system is rectangular; otherwise, oblique.
The cascaded series usually serves to amplify the effect.
See constellation.
A vacuum tube consisting essentially of an electron gun producing a concentrated electron beam (or cathode ray) which impinges on a phosphorescent coating on the back of a viewing face (or screen). The excitation of the phosphor produces light, the intensity of which is controlled by regulating the flow of electrons. Deflection of the beam is achieved either electromagnetically by currents in coils around the tube, or electrostatically by voltages on internal deflection plates.
A light so concentrated by means of refracting lenses or prisms is a dioptric light.
2. Short for celestial navigation.
The horizon, celestial equator, ecliptic, and galactic systems of celestial coordinates are based on the celestial horizon, celestial equator, ecliptic, and galactic equator, respectively, as the primary great circle. See coordinate, Table VI, for a comparison of the systems.
The expression usually refers to the upper branch, that half of the great circle from pole to pole which passes through the zenith; the other half being the lower branch. The celestial meridian coincides with the hour circle through the zenith and the vertical circle through the elevated pole.
Celestial navigation usually refers to the process as accomplished by a human operator. The same process accomplished automatically by a machine is usually termedcelestial guidanceor sometimes automatic celestial navigation.
The expression may also be applied to the data obtained by such measurement.
Instrument aboard SOHO which analyzes the constituents of the solar wind.
Same as centigrade temperature scale.
The Ninth General Conference on Weights and Measures (1948) replaced the designation degree centigrade by degree Celsius.
See constellation.
A prefix meaning one-hundredth.
A temperature scale with the ice point at 0° and the boiling point of water at 100°. Now called Celsius temperature scale.
Conversion to the Fahrenheit temperature scale is according to the formula
One-hundredth of a meter; approximately 0.3937 U.S. inch, exactly 1/2.54 inch.
A system of units based on the centimeter as the
A unit of viscosity. See poise.
2. Usually capitalized. The place, facility, or activity from which this control is exercised; specifically, at Cape Canaveral or at Vandenberg AFB, the place, facility, or activity at which the whole action incident to a test launch and flight is coordinated and controlled, from the make-ready at the launch site and on the range, to the end of the rocket flight downrange.
For a few seconds during the actual launch, control of a missile is exercised from the blockhouse, but it almost immediately reverts to Central Control for guidance and tracking, with two men in essential control. One of these is the supervisor of range operations, the other is the range safety officer.
Gravitation is considered as a central force in celestial mechanics.
2R,
where is the angular
speed of rotation; and R is the radius of curvature of the path. This
magnitude may also be written as V2/R, in terms of the linear
speed V. This force (per unit mass) is equal and opposite to the centripetal
acceleration. Also called centrifugal acceleration. The centrifugal force on the earth and atmosphere due to rotation about the earth's axis is incorporated with the field of gravitation to form the field of gravity.
This phenomenon is analogous to the generation of a shock wave when an object is traveling faster than the sound velocity of the medium. A bow wave is set up which radiates energy into the medium and slows down the object.
The angle that the cone of luminescence makes with the direction of motion of the particle can be used to measure the velocity of the particle.
See constellation.
Chadless punching is used where it is undesirable to mutilate information written or printed on the punched medium.
This recovery time provides the possibility of simultaneously interrogating and tracking the beacon by as many radars as required so long as they are phased, synchronized, or the sum total pulse recurrence frequency does not exceed the maximum pulse recurrence frequency characteristics of the beacon.
In the neutron-fission chain reaction, a neutron striking a fissionable atom causes a fission releasing neutrons which cause other fissions.
See constellation.
The pressure of gases within the combustion chamber of a rocket engine.
The volume of the rocket combustion chamber including the convergent portion of the nozzle up to the throat.
2. In computer operations: (a) That portion of a storage medium which is accessible to a given reading station. See track. (b) A path of flow, usually including one or more operations.
Some of the basic assumptions used to develop the equation were that the ionizing radiation from the sun is essentially monochromatic, that the ionized constituent is distributed exponentially (with a constant scale height), and that there is an equilibrium condition between the creation of free electrons and their loss by recombination.
For example, a decimal digit (0 to 9), a letter (A to Z), or a symbol (comma, plus, minus, etc.).
The characteristics of an aircraft are (1) qualities such as stability, maneuverability, and strength; (2) features such as number, kind, or power of engines, and size, shape, or number of wings; and (3) capabilities such as range, speed, and payload.
The length of a straight cylindrical tube having the same volume as the chamber of a rocket engine would have if it had no converging section.
2. A linear algebraic equation determining the eigenvalues or free waves of a boundary value problem. See characteristic value problem.
Of a rocket engine, a descriptive parameter,
) A convenient reference length (usually constant) of a given configuration, such as overall length of an aircraft, the maximum diameter or radius of a body of revolution, a chord or span of a lifting surface, etc.
An important example of a physical problem which leads to a characteristic value problem is the determination of the modes and frequencies of a vibrating system. In this case the dependent variable of the differential equation represents the displacements of the system and the parameter represents the frequencies of vibration.
The use of these lines or surfaces may facilitate the solution of the equations and is known as the method of characteristics. The method has been particularly successful, for example, in the problem of finite-amplitude expansion and shock waves.
This phenomenon, which is sometimes called electrical neutrality, is a result of the extremely large electric space charge fields that would arise if the densities were not equal. Although the positive and negative charge densities are seldom exactly equal, their percentage difference is so small as to be negligible. It is not difficult to maintain this condition in an active plasma since ionization or recombination always produces or destroys an ion pair together.
2. A familiarization flight in an aircraft, or a flight in which a pilot or other aircrew member or members are tested or examined for proficiency.
2. The sequence of steps taken to familiarize a person with the operation of an airplane or other piece of equipment.
In sense 1, a checkout is usually taken at a transition point between one phase of action and another. To shorten the time of checkout, automation is frequently employed.
Chemical changes, according to the nature of the materials entering into the change, may be induced by heat (thermochemical), light (photochemical), and electric (electrochemical) energies.
2. A fuel that uses special chemicals, such as the fuel once projected for the afterburner of the B-70.
This entire region is the seat of a number of important photochemical reactions involving atomic oxygen O, molecular oxygen O2, ozone O3, hydroxyl OH, nitrogen N2, sodium Na, and other constituents to a lesser degree.
The formula for chi square (x2) depends upon intended use, but is often expressible as a sum of terms of the type (f - h)2 / h where f is an observed frequency and h is its hypothetical value.
2. (symbol c). In aeronautics, a straight line intersecting or touching an airfoil profile at two points; specifically, that part of such a line between two points of intersection.
This line is usually a datum line joining the leading and trailing edges of an airfoil, joining the ends of the mean line of an airfoil profile, from which the ordinates and angles of the airfoil are measured. As such a datum line, it is sometimes called the geometric chord, to distinguish it from a chord established on the basis of any other considerations.
3. = chord length.
In sense 3, points or stations along a chord are designated in percentages or fractions of the chord or chord length from the leading edge, as, a point at 25 percent, or one-quarter, chord.
For many airfoils, the chord is established intersecting the airfoil profile at its extremities, and the chord length is equal to the length of the chord between the points of intersection; for airfoils where the chord is established by a point or points of tangency or intersection not at the extremities, however, the chord length is considered to extend beyond either or both points, as necessary, to equal the maximum length of the profile. See chord, senses 2 and 3.
See constellation.
A measure of the accuracy with which a rocket or missile can be guided; the radius of the circle at a specific distance in which 50 percent of the reliable shots land. Also called circular error probable, circle of probable error.
Circular area = 1.2733 * true area.
True area = 0.785398 * circular area.
In rocketry, the diameter of a circle within which 75 percent of the events under study occur. CD = 3.330
where
= standard deviation. Circular dispersion is most often used as a measure of error of the accuracy with which rockets reach their intended target.
).
One circular mil = 7.85 x 10-7 square inch.
A circularly polarized wave is equivalent to two super-posed plane polarized waves of sinusoidal form in which the displacements have the same amplitude, lie in perpendicular planes, and are in quadrature.
This term is usually applied to transverse waves.
2. A precise measure of the average flow of fluid along a given closed curve. Mathematically, circulation is the line integral.
By Stokes theorem, the circulation about a plane curve is equal to the total vorticity of the fluid enclosed by the curve.
The given curve may be fixed in space or may be defined by moving fluid parcels.
Cladding is used extensively in nuclear reactor cores to prevent corrosion of the fissionable material by the coolant.
2. A network for adjusting the absolute voltage level of a waveform.
V) where p is pressure; T
is temperature; L is the latent heat of the phase change; and V
is the difference in volume of the phases. Also called Clapeyron equation,
Clausius-Clapeyron equation. 2. In aeronautics, the process of improving external shape and smoothness of an aircraft to reduce its drag.
One clo is roughly equivalent to the amount of insulation provided by the average businessman's suit in a temperature climate.
2. In mathematics, a system of differential equations and supplementary conditions such that the values of all the unknowns (dependent variables) of the system are mathematically determined for all values of the independent variables (usually space and time) to which the system applies.
3. = closed ecological system.
4. A system which constitutes a feedback loop so that the inputs and controls depend on the resulting output. For example, an automatic radar-controlled tracking system.
2. A system used to check out test vehicle or telemetry performance without radiation of radio-frequency energy.
2. The place or time of such an event.
For insolation (incoming solar radiation), clouds absorb rather small fractions, particularly of the shorter wavelengths. Even for depths of clouds of the order of 20,000 feet, measurements suggest absorptions of less than 30 percent, while layers only 1000 to 2000 feet thick may absorb only about 5 percent. However, for long wave terrestrial radiation, even very thin layers of cloud act as almost complete blackbody absorbers.
Cloud physics, broadly considered, embraces not only the study of condensation and precipitation processes in clouds, but also radiative transfer, optical phenomena, electrical phenomena, and a wide variety of hydrodynamic and thermodynamic processes peculiar to natural clouds.
As compared with interference, clutter refers more particularly to unwanted reflections on a radar plan position indicator, such as ground return, but the terms are often used interchangeably.
2. = window.
2. A prefix meaning in common, as in coaxial, having a common axis.
Coast is used to prevent lock-on to a stronger target if approached by the target being tracked.
2. The set of characters resulting from the use of a code as defined in sense 1.
3. Specifically, to translate a problem to a routine expressed in machine language for a specific computer.
4. To express given information by means of a code, to encode.
1. A number indicating the amount of some change under certain specified conditions, often expressed as a ratio.
For example, the coefficient of linear expansion of a substance is the ratio of its change in length to the original length for a unit change of temperature from a standard.
2. A constant in an algebraic equation.
3. One of several parts which combine to make a whole, as the maximum deviation produced by each of several causes.
V/
p)T
This diffusion coefficient is a property of the gases in question and of the assumed nature of the molecular impacts in the diffusion process. For rigid, perfectly elastic, spherical molecules the coefficient of mutual diffusion d1,2 is, in square centimeters per second,
1, 2
and m1, m2 are the effective molecular diameters
and masses of the two gases, respectively; T is the temperature,°K;
and k is Boltzmann constant. p/
T)V
This is limited to those wave trains which have fixed or slowly varying phase relationships with each other.
In contract are the rapid interference phenomena produced by the superposition of the more or less randomly scattered waves from hydrometeors.
2. Having a fixed relation between frequency and phase of input and output signal.
Hills, buildings, and slowly moving point targets such as ships are examples of objects which produce coherent radar echoes. Volume targets (such as clouds and precipitation) give noncoherent echoes. The classification of an echo as coherent or noncoherent is closely related to the spatial resolution (beam width) of the radar or the volume occupied by the radar pulse. Thus, small atmospheric inhomogeneities which give rise to noncoherent echoes, would give coherent echoes if the radar volume were reduced in size to the order of magnitude of the inhomogeneities themselves.
An oscillator which provides a reference by which the radio frequency phase difference of successive received pulses may be recognized. See coherent reference.
Usually a number of cores are arranged in the form of a matrix.
One form of gage is a transparent tube in which the color and form of a cold-cathode discharge, without the presence of a magnetic field, give an indication of the pressure and the nature of the gas. The Philips ionization gage, or Penning gage, is a cold-cathode ionization gage in which a magnetic field is used. Various modifications of the Penning gage are named after the inventors, and certain types are referred to as magnetron vacuum gages.
The normal response is an increase in both heart rate and blood pressure.
2. To adjust the line of sight of an optical instrument, such as a theodolite, in proper relation to other parts of the instrument.
The products of the collision may or may not be the same as the precollision particles. The collision may be actual contact or the close approach and deflection of the particles.
In the case of cyclotron radiation, the collision will actually change the phase of the radiation. For many collisions, this has the effect of broadening the observed frequencies by an amount equal to the collision rate.
2. In gas dynamics and atomic physics, any of several parameters, such as cross section, collision rate, mean free path, etc., which provide a measure of the probability of collision.
A system of liquid or solid particles colloidally dispersed in a gas is called an aerosol. A system of solid substance or water-insoluble liquid colloidally dispersed in liquid water is called a hydrosol. There is no sharp line of demarcation between true solutions and colloidal system on the one hand, or between mere suspensions and colloidal systems on the other. When the particles of the dispersed phase are smaller than about 1 millimicron in diameter, the system begins to assume the properties of a true solution; when the particles dispersed are much greater than 1 micron, separation of the dispersed phase from the dispersing medium becomes so rapid that the system is best regarded as a suspension.
The difference between the apparent color index of a star and its true color index as computed for its stellar type.
Color excess is a measure of space reddening.
Of a star, the numerical difference between the apparent photographic magnitude and the apparent photovisual magnitude mpv or
The color index is zero for class A0 stars of magnitudes between 5.5 and 6.5; it is positive for red stars and negative for bluish stars. Various other color indices can be formed by using apparent magnitudes measured in other systems. Thus, the intrinsic color index is apparent photographic magnitude minus apparent ultraviolet magnitude.
An emulsion sensitive not only to blue, violet, and ultraviolet, but also to yellow and green, is called orthochromatic; if sensitive to red as well, it is called panchromatic.
If such a body were an ideal blackbody, the temperature so estimated would be its true temperature and would also agree with its effective temperature; but for actual bodies, the color temperature is generally only an approximate value. Thus, the sun's color temperature is about 6100° K, a few hundred degrees hotter than most approximations of its effective temperature.
2. The temperature to which a blackbody radiator must be raised in order that the light it emits may match a given light source in color. [Usually expressed in Kelvin (°K).]
See constellation.
2. In an optical system, a result of spherical aberration in which a point source of light, not on the axis, has a blurred, comet-shaped image.
See constellation.
Generally applied to the largest error due to the combined effect of nonlinearity and hysteresis.
Any chamber for the combustion of fuel, specifically that part of the rocket engine in which the combustion of propellants takes place at high pressure. Also called chamber, firing chamber.
The combustion chamber plus the diverging section of the nozzle comprise the rocket thrust chamber.
The orbits of comets are highly elliptical.
2. Referring to or measured from compass north.
2. Also applied to the overall system with reference to how well its various subsystems work together, as in the vehicle has good compatibility.
3. Also applied to materials which can be used in conjunction with other materials which can be used in conjunction with other materials and not react with each other under normal operating conditions.
Thus, 50° is the complement of 40°, and the two are said to be complementary. See explement.
2. The true complement of any quantity in positional notation, i.e., the quantity which, when added to the first quantity, gives the least quantity containing one more place.
3. The base-minus-one complement of any quantity in positional notation; i.e., the quantity which, when added to the first quantity, gives the largest quantity containing the same number of places.
In many computing machines a negative quantity is represented as a complement of the corresponding positive quantity.
2. Pertaining to a magnitude composed of a real number and an imaginary number.
2. = coefficient of compressibility.
In aerodynamics, this property of the air is manifested especially at high speeds (speeds approaching that of sound and higher speeds). Compressibility of the air about an aircraft may give rise to buffeting, aileron buzz, shifts in trim, and other phenomena not ordinarily encountered at low speeds, known generally as compressibility effects.
2. More generally, the act of compressing, pressing together; as in compression waves, compression ratio.
Compressors are distinguished (1) by the manner in which fluid is handled or compressed, as the axial flow, centrifugal, double-entry, free-vortex, mixed-flow, single-entry, and supersonic compressor; or (2) by the number of stages, as the multistage or single-stage compressor. See individual entries on the different types.
c)
Of a particle, the distance h/mc, where h is the Planck constant, m is the mass of the particle, and c is the velocity of light.
The Compton wavelength of the electron (symbol
c)
is 2.4261 x 10-10 centimeter; of the proton (symbol cp)
is 1.32140 x 10-13 centimeter. 2. One who computes, or who operates a computer.
2. Specifically, in meteorology, the transformation from vapor to liquid. See sublimation.
2. Specifically, in meteorology, a particle upon which condensation of water begins in the atmosphere.
There are three kinds of condensation trails: the aerodynamic type, caused by reduced pressure of the air in certain areas as it flows past the aircraft; the convection type, caused by the rising of air warmed by an engine; and the engine-exhaust, or exhaust-moisture, type, formed by the ejection of water vapor from an engine into a cold atmosphere.
2. In vacuum systems, the throughput Q under steady-state conservative conditions divided by the measured difference in pressure p between two specified cross sections inside a pumping system:
Conduction is to be distinguished from convection (of heat) and radiation (of all electromagnetic energy).
2. A unit measure of electrical conduction; the facility with which a substance conducts electricity, as represented by the current density per unit electrical-potential gradient in the direction of flow.
Electrical conductivity is the reciprocal of electrical resistivity and is expressed in units such as mhos (reciprocal ohms) per centimeter. It is an intrinsic property of a given type of material under given physical conditions (dependent mostly upon temperature). Conductance, on the other hand, varies with the dimensions of the conducting system, and is the reciprocal of the electrical resistance.
2. A type of light-sensitive cell in the retina. Cones are involved in color vision, high visual acuity, and photopic vision.
Such a cone would open wider with increasing altitude above the critical level of escape, and would be nonexistent below the critical level of escape.
For example: 95-percent confidence limits for a sample of 10 with a ratio of successes to total number tested of 0.9 (9 successes and 1 failure) would be 0.54 to 1.0. That is, even with an observed success ratio of 0.9 (90 percent) the best that can be said is that the true ratio lies between 0.54 (54 percent) and 1.0 (100 percent) an estimated 95 percent of the time.
A confidence level is always associated with some assertion and measures the probability that a given assertion is true. For example, it could be the probability that a particular characteristic will fall within specified limits, i.e., the chance that the true value of P lies between P = a and P = b. See confidence interval.
2. A geometric figure, usually consisting principally of points and connecting lines.
3. = planetary configuration.
4. A particular type of a specific aircraft, rocket, etc., which differs from others of the same model by virtue of the arrangement of its components or by the addition or omission of auxiliary equipment as long-range configuration, cargo configuration.
Some writers use constellation as a synonym for configuration in referring to the relative positions of spacecraft to each other, as in a rendezvous maneuver, or to celestial bodies. This usage should be discouraged.
The conic sections are the ellipse, the parabola, and the hyperbola, curves that are used to describe the path or bodies moving in space. The circle is a special case of the ellipse, an ellipse with an eccentricity of zero.
The conic is the locus of all points the ratio of whose distances from a fixed point, called the focus, and a fixed line, called the directrix, is constant.
2. In reference to satellite orbital parameters, without consideration of the perturbing effects of the actual shape or distribution of mass of the primary.
Thus, conic perigee is the perigee the satellite would have if all the mass of the primary were concentrated at its center.
This type of beam has an advantage over that produced by a single radiating element placed at the focus of a parabolic reflector in that much greater angular accuracy is possible in locating targets.
A planet is at superior conjunction if the sun is between it and the earth; at inferior conjunction if it is between the sun and the earth.
2. The time at which conjunction, as defined in sense 1, takes place.
The principle of conservation of angular momentum can be derived from the Newton second law of motion.
This principle takes into account all forms of energy in the system; if therefore provides a constraint on the conversions from one form to another. See energy equation.
A console is usually designed around desk-like arrays. It permits the operator to monitor and control different activating instruments, data recording instruments, or event sequences.
The maximum occurs at the time the direction of motion of the earth in its orbit is at right angles to a line from the earth to the star.
In one design for such a system, a pressure switch actuates a valve which controls the release of ballast so as to maintain flight above a selected pressure level until the supply of ballast is exhausted.
Another design is a simple nonextensible envelope capable of withstanding a differential of pressure, higher inside than out. It is inflated so that the smaller night-time pressure of the gas still fully extends the envelope. Such a superpressure balloon will keep essentially constant level until enough gas diffuses out of it to allow diurnal changes in volumes.
The genitive form of constellation names is used in star names and numbers such as Bayer name and Flamsteed number. Table V lists the constellations.
2. For electromagnetic radiation, a spectrum that exhibits no detailed structure and represents a gradual variation of intensity with wavelength from one end to the other, as the spectrum from an incandescent solid. Also called continuum, continuum radiation.
3. For particles, a spectrum that exhibits a continuous variation of the momentum or energy.
Waves, the successive oscillations of which are identical under steady-state conditions.
Two advantages of CW radar are the narrow bandwidth and low power required. Range information may be obtained by some form of modulation, e.g., frequency modulation, pulse modulation.
2. = continuous spectrum.
Where the degree is slight, the image is said to be flat. Where the difference is marked, it is said to be contrasty.
2. The difference in luminance between two portions of the visual field usually expressed as:
Since this ratio can be negative for nearly black targets at close range, and since the sign of the contrast has no psycho-physical significance, it is conventional to use only its absolute value. See threshold contrast.
2. In plural (a) A system or assembly of levers, gears, wheels, cables, boosters, valves, etc., used to control the attitude, direction movement, power, and speed of an aircraft, rocket spacecraft, etc. (b) Control surfaces or devices.
3. Sometimes capitalized. An activity or organization that directs or regulates an activity. See central control.
4. Specifically, to direct the movements of an aircraft or rocket with particular references to changes in attitude and speed. Compare guidance.
2. Specifically, in meteorology, atmospheric motions that are predominantly vertical. Compare advection.
Mathematically, convergence is negative divergence, and the latter term is used for both. (For mathematical treatment, see divergence.)
2. The property of a sequence or series of numbers or functions which ensures that it will approach a definite finite limit.
A series representation of a mathematical function exhibits convergence if the sum of the terms of the series approaches the value of the function more closely as more terms of the series are taken, the two agreeing in the limit of an infinite number of terms.
3. Decrease in area or volume.
A static device for this purpose is called a rectifier. A device for changing direct current to alternating current is called an inverter.
2. A transducer whose output is a different frequency from its input.
3. In computer terminology = conversion device.
A liquid or gas used to cool something, as a rocket combustion chamber.
This word is used in many self-explanatory compounds, which include: coolant chamber, coolant gallery, coolant hose, coolant jacket, coolant passage, coolant pump, coolant radiator.
If the point is know to be on a given line, only one coordinate is needed; if on a surface, two are required; if in space, three. Cartesian coordinates define a point relative to two intersecting lines, called axes. If the axes are perpendicular, the coordinates are rectangular; if not perpendicular, they are oblique coordinates. A three-dimensional system of Cartesian coordinates is called space coordinates. Polar coordinates define a point by its distance and direction from a fixed point called the pole. Direction is given as the angle between a reference radius vector and a radius vector to the point. If three dimensions are involved, two angles are used to locate the radius vector. Space-polar coordinates define a point on the surface of a sphere by (1) its distance from a fixed point at the center, the pole; (2) the colatitude or angle between the polar axis (a reference line through the pole) and the radius vector (a straight line connecting the pole and the point); and (3) the longitude or angle between a reference plane through the polar axis and a plane through the radius vector and the polar axis. Spherical coordinates define a point on a sphere or spheroid by its angular distances from a primary great circle and from a reference secondary great circle. Geographical or terrestrial coordinates define a point on the surface of the earth. Celestial coordinates define a point on the celestial sphere.
Table VI summarizes the terms used in four geocentric celestial coordinate systems and the terrestrial (geographic) coordinate system and indicates the analogous terms under each system.
Physically, coriolis acceleration may be considered as coming from the conservation of momentum in a body moving in a direction not parallel to the axis of rotation of the relative system.
Mathematically, coriolis acceleration comes from the differentiation of terms containing the angular velocity
in the expression
for the absolute velocity of the particle. In the case of the earth, moving with angular velocity
,
a particle moving relative to the earth with velocity v has the coriolis
acceleration 2 * v. If Newton laws are to be
applied in the relative system, the coriolis acceleration and the acceleration
of the relative system must be treated as forces. See apparent
force, coriolis force, inertial
force, gravity. Such a force is required if Newton Laws are to be applied in the system.
sin 
,
where is the angular
speed of the earth and is
the latitude. It is observed at solar eclipse or with the coronagraph. The shape of the corona varies during the sunspot cycle. At sunspot minimum the corona has large extensions along the sun's equator, with short brushlike tufts near the poles. At sunspot maximum the equatorial extensions are much smaller and the corona is more regular in shape. The temperature of the corona appears to be in the vicinity of 1,000,000° K.
2. The extremely tenuous outer atmosphere of the sun now known to extend past the earth's orbit.
3. A set of one or more prismatically colored rings of small radii, concentrically surrounding the disk of the sun, moon, or other luminary when veiled by a thin cloud.
The corona is due to diffraction by numerous water drops. It can be distinguished from the relatively common halo of 22° by the much smaller angular diameter of the corona, which is often only a few degrees, and by its color sequence, which is from blue inside to red outside, the reverse of that in the 22° halo.
4. See corona discharge.
5. See aurora.
6. See geocorona.
See constellation.
Great care must be taken to avoid light scattered from the atmosphere and the lenses, and from reflections in the tube of the instrument. The coronograph is used with a narrow-band polarizing filter or with a spectroscope.
For 1000 protons there are about 80 helium nuclei, about 3 nuclei in the carbon-nitrogen-oxygen range, and 1 or 2 heavier nuclei. The proton energy may be as high as 105 Bev, and the other nuclei show an energy distribution similar to that of the protons.
Although this theory was later replaced by the wave theory of light, the concept of photons in the modern quantum theory is reminiscent of Newton theory.
1. In statistics, a relationship between two occurrences
which is expressed as number between minus one (-1) and plus one (+1).
2. When used without further qualification, the statistical term correlation usually refers to simple, linear correlation between two variables x and y and is measured by the product-moment coefficient of correlation
or its sample estimate r defined
as follows, where the respective population mean values of x and
y are denoted by 
and 
,
the respective standard deviations by (
x ) and ( y ), and
where E is the expected value:
2. When used without further qualification, the statistical term correlation usually refers to simple, linear correlation between two variables x and y and is measured by the product-moment coefficient of correlation
or its sample estimate r defined
as follows, where the respective population mean values of x and
y are denoted by and ,
the respective standard deviations by (
x ) and ( y ), and
where E is the expected value:
The product-moment E[(x - )(y -
)] is usually called the
covariance of x and y. See autocorrelation,
partial correlation.
In connection with correlation, the word simple is used in contradistinction
to other qualifiers such as multiple or partial. The word
linear refers to a linear relationship between the two variables,
or more precisely, to a linear approximation of the regression
function of either variable with respect to the other.
is
* F" where 