Precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called nutation. In physics, there are two types of precession: torque-free and torque-induced.
In astronomy, "precession" refers to any of several slow changes in an astronomical body's rotational or orbital parameters, and especially to Earth's precession of the equinoxes. (See section Astronomy below.)
Torque-free
Torque-free precession implies that no external moment (torque) is applied to the body. In torque-free precession, the angular momentum is a constant, but the angular velocity vector changes orientation with time. What makes this possible is a time-varying moment of inertia, or more precisely, a time-varying inertia matrix. The inertia matrix is composed of the moments of inertia of a body calculated with respect to separate coordinate axes (e.g. x, y, z). If an object is asymmetric about its principal axis of rotation, the moment of inertia with respect to each coordinate direction will change with time, while preserving angular momentum. The result is that the component of the angular velocities of the body about each axis will vary inversely with each axis' moment of inertia.
Precession (mechanical)
Precession, also called epicyclic fretting precession, (or more accurately hypocyclic fretting precession since "epicyclic" applies to a round part spinning outside a circle and "hypocyclic" applies to a round part spinning inside a circle) is the process of a round part in a round hole rotating with respect to that hole because of clearance between them and a radial force on the part that changes direction. The direction of rotation of the inner part is opposite to the direction of rotation of the radial force.Fretting between the part and the hole is often a result of this motion. "In machinery, fretting is the micro-motion of tightly fitting parts that superficially appear immobile with respect to each other."
"For a pedal, a rotating load arises from downward pedaling force on a spindle rotating with its crank making the predominantly downward force effectively rotate about the pedal spindle. What may be less evident is that even tightly fitting parts have relative clearance due to their elasticity, metals not being rigid materials as is evident from steel springs. Under load, micro deformations, enough to cause motion, occur in such joints. This can be seen from wear marks where pedal spindles seat on crank faces."
Precession (disambiguation)
Precession refers to a specific change in the direction of the rotation axis of a rotating object, in which the second Euler angle (angle of nutation) is constant
Precession may specifically mean:
Podcasts:
Precession
ALBUMS
- Mur Mur: Conversation Mix released: 2007
- Time Warp Compilation 07 released: 2007
- Adventures in Techno Soul released: 1996
- Retrograde Motion EP released: 1995
Mur Mur: Conversation Mix
Released 2007- The River (Sr Replicante Sub Urban mix)
- Boom Bip
- White Tea Deciple
- This Never Works
- Junction
- While You Sleep
- Ndank Ndank…
- Liquid
- Surge
- Sandcastle
- India in Me (mix 1)
- Increments (Exercise One remix)
- Elwico
- Joakhim
- Just Wanna Get Down rmx (Audio Werner rmx)
- Uncomplicate Yourself (Sweet'n Candy remix)
- You Must Protect Youfself
- Dump Truck
Time Warp Compilation 07
Released 2007- Where's My Dongle?
- Class (Loco Dice remix)
- November in Little Albio Street
- Ronan's BBQ (Xhin remix)
- Tainted Words (Plasmik remix)
- New Day (dub)
- Vincent Hanna
- Berlin Has No Cows
- Take Action (Cassy remix)
- A Chico a Rhytmico
- Anador Lunar
- Runny
- Time Is Now (Radio Slave Panorama Garage remix)
- Collaboration Alpha
Adventures in Techno Soul
Released 1996- Venus Fly Trap (Derrick Carter remix)
- Wake Up to the Source (Russ Gabriel remix)
- Lost Point (Claude Young & Ian O'Brien remix)
- Storm the Funk (Mark Broom remix)
- Sandcastle (Mike Huckaby remix)
- End of the Road (Kenny Dixon Jr remix)
- Galapagos Theory (Steve Paton remix)
- Origin of Species (Carl Craig remix)
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Like A Plague Upon The Earth
by: ProcessionThe children cry
As the bleeding mother prays
No faith for salvation was enough
The beast is born
The young have died
So the old men in disguise
The black pest has risen
Mankind fails before my eyes
To spread the sorrow and despair
Waking!
Like a plague upon the earth
... Evil!