DOORS AND GATES |
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A door is a generally floor-length opening in a wall (or other partition), often equipped with a hinged or sliding panel which can be moved to leave the opening accessible, or to close it more or less securely. Doors are nearly universal in structures of all kinds (especially houses and other buildings), allowing passage between inside and outside, or among internal rooms. Doors are also found in vehicles, cupboards, cages, etc. A gate is a point of entry to a space enclosed by walls, or an opening in a fence. Gates may prevent or control entry or exit, or they may be merely decorative.
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FIBER OPTICS |
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An optical fiber (or fibre) is a transparent thin fiber, usually made of glass or plastic, for transmitting light. Fiber optics is the branch of science and engineering concerned with such optical fibers.
Optical fibers are commonly used in telecommunication systems, as well as in illumination, sensors, and imaging optics.
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HVAC - HEAT VENTITATION AIR CONDITIONING |
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HVAC (pronounced either "H-V-A-C" or, occasionally, "H-VAK") is an initialism/acronym that stands for "heating, ventilation and air-conditioning". This is sometimes referred to as climate control.
These three functions are closely interrelated, as they control the temperature and humidity of the air within a building in addition to providing for smoke control, maintaining pressure relationships between spaces, and providing fresh air for occupants. In modern building designs, the design, installation and control systems of these functions are integrated into a single "HVAC" system.
The term air handler can mean a whole unit including the blower, heating and cooling elements, filter racks or chamber and dampers, but not including the ductwork through the building.
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LEAD |
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Lead is a chemical element in the periodic table that has the symbol Pb (L. plumbum) and atomic number 82. A soft, heavy, toxic and malleable poor metal, lead is bluish white when freshly cut but tarnishes to dull gray when exposed to air. Lead is used in building construction, lead-acid batteries, bullets and shot, and is part of solder, pewter, and fusible alloys. Lead has the highest atomic number of all stable elements. (But see the article on Bismuth, which has a half life so long it can be considered stable.)
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MOTORCYCLE HELMETS |
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A motorcycle helmet is a type of protective headgear used by motorcycle riders. The primary goal of a motorcycle helmet is to protect the rider's head during impact, although many helmets provide additional conveniences, such as face shields, ear protection, intercom etc.
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