HELICOPTERS |
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A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors (propellers). Helicopters are classified as rotary-wing aircraft to distinguish them from conventional fixed-wing aircraft. The word helicopter is derived from the Greek words helix (spiral) and pteron (wing). The engine-driven helicopter was invented by the Slovak inventor Jan Bahyl. The first stable, single-rotor, fully-controllable helicopter to enter large full-scale production was made by Igor Sikorsky in 1942.
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INDOOR AIR QUALITY (IAQ) |
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Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. The IAQ may be compromised by microbial contaminants (mold, bacteria), chemicals(such as carbon monoxide,radon}, allergens, or any mass or energy stressor that can induce health effects. Often it is perceived that outdoor air is polluted, but indoor air is acceptable. Scientific studies illustrate the falsity of this perception, and, in fact, indoor air is often a greater health hazard than the corresponding outdoor setting.
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TRANSPORTATION |
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Transport or transportation is the movement of people and goods from one place to another.
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