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| Par lamp
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Par is an acronym for parabolic aluminized reflector. A par lamp which may utilize either an incandescent filament, a halogen filament tube or hid arc tube is a precision pressed-glass reflector lamp. Par lamps rely on both the internal reflector and prisms in the lens for the control of the light beam. |
| Parabolic aluminized reflector lamp
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A type of lamp having a lens of heavy durable glass that focuses the light. They have longer lifetimes with less lumen depreciation than standard incandescent lamps. |
| Parabolic arch
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Also called Tudor, Gothic, or semicircular arches, they are arches which have a span of more than six feet with a rise-to-span ratio in excess of 0.15, having a load capacity of 1,000 pounds per foot. |
| Parabolic dish
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A solar energy conversion device that has a bowl shaped dish covered with a highly reflective surface that tracks the sun and concentrates sunlight on a fixed absorber, thereby achieving high temperatures, for process heating or to operate a heat (Stirling) engine to produce power or electricity. |
| Parabolic louver
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A devise composed of cells constructed in a parabolic shape with a specular finish. This shape provides better light control, thus reducing glare and light pollution. |
| Parabolic trough
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A solar energy conversion device that uses a trough covered with a highly reflective surface to focus sunlight onto a linear absorber containing a working fluid that can be used for medium temperature space or process heat or to operate a steam turbine for power or electricity generation. |
| Parallax
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A distortion or incorrect interpretation of what is seen when objects are located on in front of the other, and apparently looks as though it is one thing, when in fact it is another, such a an indicator being read from the side rather than from the front. |
| Parallel
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Similar property. Properties that are side by side but do not meet. |
| Parallel application
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Drywall (wallboard) installation with the long edge running in the direction of the framing rather than perpendicular to it, as it is normally. |
| Parallel circuit
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Electrical circuit with the loads connected across the power source instead having the power source pass through each load in the series, keeping unbroken continuity of the circuit, so that if one fails, the other do not. |
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