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In astrophysics, particularly the study of accretion disks, the epicyclic frequency is the frequency at which a radially displaced fluid parcel will oscillate. It can be referred to as a "Rayleigh discriminant". When considering an astrophysical disc with differential rotation , the epicyclic frequency is given by
, where R is the radial co-ordinate.[1]
This quantity can be used to examine the 'boundaries' of an accretion disc: when becomes negative, then small perturbations to the (assumed circular) orbit of a fluid parcel will become unstable, and the disc will develop an 'edge' at that point. For example, around a Schwarzschild black hole, the innermost stable circular orbit (ISCO) occurs at three times the event horizon, at .
For a Keplerian disk, .
^p161, Astrophysical Flows, Pringle and King 2007
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astrophysics, particularly the study of accretion disks, the epicyclicfrequency is the frequency at which a radially displaced fluid parcel will oscillate...
which an object's epicyclicfrequency (the rate at which one periapse follows another) is a simple multiple of some forcing frequency. Resonances of this...
maintain the spiral structure if the frequency at which a star passes through the arms is less than the epicyclicfrequency, κ ( R ) {\displaystyle \kappa (R)}...
angular frequency ω {\displaystyle \omega } satisfies the equation where κ 2 {\displaystyle \kappa ^{2}} is known as the epicyclicfrequency. In our solar...
the Galaxy. As well, in the epicyclic approximation for nearly circular stellar orbits in a disk, the epicyclicfrequency κ {\displaystyle \kappa } is...
that. The rack and pinion gear type is also used in a rack railway. In epicyclic gearing, one or more of the gear axes moves. Examples are sun and planet...
sun gear Fixed internal gear Belt drive Epicyclic gearing The Rolls-Royce Falcon engine of 1915 featured epicyclic propeller reduction gearing which contained...
medieval Al-Andalus described a water clock that employed both segmental and epicyclic gearing. Islamic water clocks, which used complex gear trains and included...
and frequency (about 10 GHz, also for economic reasons). The radio source PSR J1928+15 (observed in 2005 near the Galactic disk, at a frequency of 1...
are categorized as linear integrated circuits and RF circuits (radio frequency circuits). Mixed-signal integrated circuits are categorized as data acquisition...
then included direct drive and slow motion capacitors that incorporated epicyclic ball-bearing reduction units. The ‘Dilecon’ solid dielectric variable...
August 2022. Bose, Bimal K, ed. (1996). Power Electronics and Variable Frequency Drives: Technology and Applications. Wiley Online Library. doi:10.1002/9780470547113...
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incorporating a direct drive, large diameter brushroll with an internal "epicyclic" geared motor, similar to the DC50 and Small Ball. The powerhead has 3...
company, were necessary because in that four-wheel drive (4×4) vehicle the epicyclic final drive was in the wheel hubs and therefore left no room for conventional...
start. Some clutch disks include springs designed to change the natural frequency of the clutch disc, in order to reduce NVH within the vehicle. Also, some...
interposed between the engine and gearbox, and the gearbox is often of the epicyclic (planetary) type to permit shifting while under load. Various systems...
communicate with distant command centers or other ships. One is VLF (very low frequency) radio, which can reach a submarine either on the surface or submerged...
the difference between wheel and engine speed. The differential is an epicyclic gear set (also called a "power split device"); that and the two motor-generators...
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interposed between the engine and gearbox, and the gearbox is often of the epicyclic (planetary) type to permit shifting while under load. Various systems...
signature management technology – Camouflage designed to work at multiple frequencies, not just visible lightPages displaying short descriptions of redirect...
suction stage and a separate high-speed pressure stage coupled through an epicyclical gearbox. Each unit had an automatic microwire suction strainer supplemented...
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