Quadrat: An ecological sampling unit that consists of a square frame of known area. The quadrat is used for quantifying the number or percent cover of a given species within a given area. See also transect.

 

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Quadrat: An ecological sampling unit that consists of a square frame of known area. The quadrat is used for quantifying the number or percent cover of a given species within a given area. See also transect.

Quadratic Programming: Variant of linear programming in which the objective function is quadratic rather than linear. In portfolio selection, we often minimize the variance of the portfolio (which is a quadratic f . . . View Full Definition

Quadrature Amplitude Modulation (QAM): A method of modulating digital signals using both amplitude and phase coding. Used for downstream and can be used for upstream.

Quadrate, Quartile: Synonymous with square. See Square.

Quadrature Of Moon: Position of the Moon when its longitude differs by 90° from the longitude of the Sun. The corresponding phases are known as first quarter and last quarter.

Quadrature Phase-Shift Keying (QPSK): A method of modulating digital signals using four phase states to code two digital bits per phase shift.

Sesquiquadrate, Sesqui-Square: A multiple of the semi-square, and eighth harmonic aspect. A minor hard aspect, separating distance 135°, its influence is frictional.

Sesquiquadrate: An arc of 135 degrees, a 'square-and-a-half.' A minor aspect indicating tension and challenge.

Phase Inequality: Variations in the tides or tidal currents due to changes in the phase of the Moon. At the times of new and full Moon the tide-producing forces of the Moon and Sun act in conjunction, causing . . . View Full Definition

Neap Tides Or Tidal Currents: Tides of decreased range or tidal currents of decreased speed occurring semimonthly as the result of the Moon being in quadrature. The neap range (Np) of the tide is the average range occurr . . . View Full Definition