upper dead center

bottom dead center

BTDC Before Top Dead Center

dead center

top dead center

water diversion from the upper Yangtze River in the south to the upper Yellow River in the north

bias between the mass center and siffness center

center to center (C-C)

center to center communications

center to center distance

center-to-center

1221 upper working face

2×2 Upper Triangular Operator Matrixes

95% Upper confidence limit

Aberdeen Upper Reservoir

accepted upper limit

Accommodation above the Upper Deck

accurate upper bound solution

Acquired absence of both upper limbs [any level]

Acquired absence of upper limb above wrist