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R RS commonly used symbol for source impedance. commonly used symbol for transforRT mation ratio. R-ALOHA RL
See reservation ALOHA.
Typical symbol for load resistance.
Rabi frequency the characteristic coupling strength between a near-resonant electromagnetic field and two states of a quantum mechanical system. For example, the Rabi frequency of an electric dipole allowed transition is equal to µE/hbar, where µ is the electric dipole moment and E is the maximum electric field amplitude. In a strongly driven 2-level system, the Rabi frequency is equal to the rate at which population oscillates between the ground and excited states. race condition a situation where multiple processes access and manipulate shared data with the outcome dependent on the relative timing of these processes. raceway a channel within a building which holds bare or insulated conductors. radar an instrument that transmits electromagnetic waves and receives properties of the reflected electromagnetic wave from the target, which can be used to determine the nature and distance to the target. Radar is an acronym that stands for radio detection and ranging. radar cross section (RCS) a measure of the reflective strength of a radar target; usually represented by the symbol s, measured in square meters, and defined as 4π times the
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ratio of the power per unit solid angle scattered in a specific direction of the power unit area in a plane wave incident on the scatterer from a specified direction. RADHAZ radiation hazards to personnel as defined in ANSI/C95.1-1991 IEEE Standard Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz. radial basis function network a fully connected feedforward network with a single hidden layer of neurons each of which computes a nonlinear decreasing function of the distance b