structured cabling consists of six subsystems: entrance facilities is the point where the telephone company network ends and connects with the on-premises wiring belonging to the customer. equipment rooms house equipment and wiring consolidation points that serve the users inside the building or campus.
in railway signalling, a token is a physical object which a train driver is required to have or see before entering onto a particular section of single track.the token is clearly endorsed with the names of the section it belongs to. a token system is more commonly used for single lines because of the greater risk of collision in the event of a mistake being made by a signaller or traincrew .
functional flow block diagram format. a functional flow block diagram ffbd is a multi-tier, time-sequenced, step-by-step flow diagram of a system ’s functional flow. the term 'functional' in this context is different from its use in functional programming or in mathematics, where pairing 'functional' with 'flow' would be ambiguous.
a wiring diagram is a simplified conventional pictorial representation of an electrical circuit. it shows the components of the circuit as simplified shapes, and the power and signal connections between the devices. a wiring diagram usually gives information about the relative position and arrangement of devices and terminals on the devices, to help in building or servicing the device.
knob-and-tube wiring sometimes abbreviated k&t is an early standardized method of electrical wiring in buildings, in common use in north america from about 1880 to the 1930s. it consisted of single-insulated copper conductors run within wall or ceiling cavities, passing through joist and stud drill-holes via protective porcelain insulating tubes, and supported along their length on nailed .
the doubleday myth refers to the belief that the sport of baseball was invented in 1839 by future american civil war general abner doubleday in cooperstown, new york.in response to a dispute over whether baseball originated in the united states or was a variation of the british game rounders, the mills commission was formed in 1905 to seek out evidence. . mining engineer abner graves authored .
direct current dc is the unidirectional flow of an electric charge.an electrochemical cell is a prime example of dc power. direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.the electric current flows in a constant direction, distinguishing it from alternating current ac .