Where does sweep collide?

In aeronautics, sweep is the angle by which a wing is raked backward (or forward) from a line perpendicular to the fuselage, chosen chiefly to delay the drag rise of compressibility by reducing the component of the airflow that acts across the wing. Anderson's Fundamentals of aerodynamics explains how sweeping a wing raises its critical Mach number, letting aircraft fly efficiently closer to the speed of sound at the cost of some low-speed lift. The referent is a fixed geometric angle of a lifting surface, and it is unrelated to a swept radar frequency or a matrix operation that happens to share the name.[1]

Unit

The sweepback angle of the wing relative to the fuselage normal

Recovery means

Not applicable

Measured by

Specified as the leading-edge or quarter-chord sweep angle and tied to the wing's critical Mach number

In signal processing, a sweep (or chirp) is a signal whose frequency changes steadily across its duration, sliding from a low to a high tone (or the reverse). Klauder and colleagues' The theory and design of chirp radars showed that transmitting such a swept-frequency pulse and compressing it on reception yields both long-range energy and fine range resolution, the basis of pulse-compression radar and of frequency-sweep methods throughout acoustics and communications. The referent is a time-varying-frequency waveform, characterised by its sweep rate and bandwidth, and it has nothing to do with a wing's geometry or a statistical pivot.[2]

Unit

The rate at which frequency changes over the duration of the signal

Recovery means

Not applicable

Measured by

Described by the start and stop frequencies, sweep rate, bandwidth, and time–bandwidth product

In computational statistics, the sweep operator is a matrix transformation that pivots on a chosen diagonal element, and applied in sequence it inverts matrices and solves the normal equations of regression while building up sums of squares and coefficient estimates. Goodnight's A tutorial on the SWEEP operator laid out how sweeping and reverse-sweeping variables in and out of a model underlie much regression and analysis-of-variance computation. The referent is an algebraic operation on a matrix, and it is an entirely different construct from a swept wing or a swept-frequency signal, sharing only the verb of passing through in order.[3]

Unit

A pivot operation applied to a chosen diagonal of a matrix

Recovery means

Not applicable

Measured by

Defined algebraically by its effect on the swept matrix; verified by reversibility and the resulting model estimates