Uninterruptible power supplyAn uninterruptible power supply (UPS) or uninterruptible power source is a type of continual power system that provides automated backup electric power to a load when the input power source or mains power fails. A UPS differs from a traditional auxiliary/emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions by switching to energy stored in battery packs, supercapacitors or flywheels.
Signal-flow graphA signal-flow graph or signal-flowgraph (SFG), invented by Claude Shannon, but often called a Mason graph after Samuel Jefferson Mason who coined the term, is a specialized flow graph, a directed graph in which nodes represent system variables, and branches (edges, arcs, or arrows) represent functional connections between pairs of nodes. Thus, signal-flow graph theory builds on that of directed graphs (also called digraphs), which includes as well that of oriented graphs.
High fidelityHigh fidelity (often shortened to Hi-Fi or HiFi) is the high-quality reproduction of sound. It is popular with audiophiles and home audio enthusiasts. Ideally, high-fidelity equipment has inaudible noise and distortion, and a flat (neutral, uncolored) frequency response within the human hearing range. High fidelity contrasts with the lower-quality "lo-fi" sound produced by inexpensive audio equipment, AM radio, or the inferior quality of sound reproduction that can be heard in recordings made until the late 1940s.
Battery roomA battery room is a room that houses batteries for backup or uninterruptible power systems. The rooms are found in telecommunication central offices, and provide standby power for computing equipment in datacenters. Batteries provide direct current (DC) electricity, which may be used directly by some types of equipment, or which may be converted to alternating current (AC) by uninterruptible power supply (UPS) equipment.
