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Plenum
Plenum may refer to: * Plenum chamber, a chamber intended to contain air, gas, or liquid at positive pressure * Plenism, or ''Horror vacui'' (physics) the concept that "nature abhors a vacuum" * Plenum (meeting), a meeting of a deliberative assembly in which all members are present; contrast with quorum * Plenum space, enclosed spaces (in buildings) used for airflow * Plenum cable, electrical wire permitted in plenum spaces per building codes * Plenum Publishing Corporation, a publisher of scientific books and journals * Plenum (physics), a space completely filled with matter * Undergravel filters, in aquarium filtration, an open space under a layer of gravel or sand * Air-mixing plenum In building services engineering and HVAC, an air-mixing plenum (or mixing box) is used for mixing air from different ductwork systems. Usage The most common application for an air-mixing plenum is the mixing of ''return air'' (or ''extract ai ..., a place where ducts meet See also * Plenar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plenum Chamber
A plenum chamber is a pressurised housing containing a fluid (typically air) at positive pressure. One of its functions is to equalise pressure for more even distribution, compensating for irregular supply or demand. It is typically relatively large in volume and thus has relatively low velocity compared to the system's other components. In wind tunnels, rockets, and many flow applications, it is a chamber upstream on the fluid flow where the fluid initially resides (approximately at rest). It can also work as an acoustic silencer. Examples of plenum chambers include those used with: * Superchargers * Hovercraft * Corliss steam engines * Raised floors and false ceilings in equipment rooms * Some organs (to supplement the bellows) * A number of aerophones, such as the bag of bagpipes and the ''slow air chamber'' of the Native American flute * Plenum chamber anesthetic vaporizers * Rocket motor combustion chambers, which may have a section near the nozzle that is free of the prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plenum Space
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure. Space between the structural ceiling and the dropped ceiling or under a raised floor is typically considered plenum; however, some drop-ceiling designs create a tight seal that does not allow for airflow and therefore may not be considered a plenum air-handling space.Thomas, Timothy"What is plenum? - Definition from WhatIs.com ''TechTarget'', September 21, 2005. Retrieved July 25, 2017. Maintenance Diligence is required to make sure that a non-plenum airspace stays that way. A non-plenum airspace can become a plenum airspace by accident if the ductwork is disconnected and not properly repaired and resealed. Ductwork disconnection can occur due to building damage such as earthquakes, aging, or adverse environment causing the metal to corrode a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plenum Cable
__NOTOC__ Plenum cable is electrical cable that is laid in the plenum spaces of buildings. In the United States, plastics used in the construction of plenum cable are regulated under the National Fire Protection Association standard NFPA 90A: Standard for the Installation of Air Conditioning and Ventilating Systems. All materials intended for use on wire and cables to be placed in plenum spaces are designed to meet rigorous fire safety test standards in accordance with NFPA 262 and outlined in NFPA 90A. Plenum cable is jacketed with a fire-retardant plastic jacket of either a low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer ( FEP). Polyolefin formulations, specifically based on polyethylene compounding had been developed by at least two companies in the early to mid-1990s; however, these were never commercialized, and development efforts continue in these yet-untapped product potentials. Development efforts on a non-halogen plenum compound were announced in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plenum Publishing Corporation
Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in Berlin, it expanded internationally in the 1960s, and through mergers in the 1990s and a sale to venture capitalists it fused with Wolters Kluwer and eventually became part of Springer Nature in 2015. Springer has major offices in Berlin, Heidelberg, Dordrecht, and New York City. History Julius Springer founded Springer-Verlag in Berlin in 1842 and his son Ferdinand Springer grew it from a small firm of 4 employees into Germany's then second largest academic publisher with 65 staff in 1872.Chronology ". Springer Science+Business Media. In 1964, Springer expanded its business internationally, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horror Vacui (physics)
In physics, horror vacui, or plenism (), commonly stated as "nature abhors a vacuum", is a postulate attributed to Aristotle, who articulated a belief, later criticized by the atomism of Epicurus and Lucretius, that nature contains no vacuums because the denser surrounding material continuum would immediately fill the rarity of an incipient void. He also argued against the void in a more abstract sense (as "separable"), for example, that by definition a void (equivocally?) itself, is nothing, and following Plato, nothing cannot rightly be said to exist. Furthermore, insofar as it would be featureless, it could neither be encountered by the senses, nor could its supposition lend additional explanatory power. Hero of Alexandria challenged the theory in the first century AD, but his attempts to create an artificial vacuum failed. The theory was debated in the context of 17th-century fluid mechanics, by Thomas Hobbes and Robert Boyle, among others, and through the early 18th century by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plenum (meeting)
A plenary session or plenum is a session of a conference which all members of all parties are to attend. Such a session may include a broad range of content, from keynotes to panel discussions, and is not necessarily related to a specific style of presentation or deliberative process. The term has been used in the teaching profession to describe when information is summarized. This often encourages class participation or networking. When a session is not fully attended, it must have a quorum: the minimum number of members required to continue process (by the group's charter or bylaws). Some organizations have standing committees that conduct the organization's business between congresses, conferences, or other meetings. Such committees may themselves have quorum requirements and plenary sessions. See also * Floor (legislative) The floor of a legislature or chamber is the place where members sit and make speeches. When a person is speaking there formally, they are said to ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quorum
A quorum is the minimum number of members of a deliberative assembly (a body that uses parliamentary procedure, such as a legislature) necessary to conduct the business of that group. According to ''Robert's Rules of Order Newly Revised'', the "requirement for a quorum is protection against totally unrepresentative action in the name of the body by an unduly small number of persons." In contrast, a plenum is a meeting of the full (or rarely nearly full) body. A body, or a meeting or vote of it, is quorate if a quorum is present (or casts valid votes). The term ''quorum'' is from a Middle English wording of the commission formerly issued to justices of the peace, derived from Latin ''quorum'', "of whom", genitive plural of ''qui'', "who". As a result, ''quora'' as plural of ''quorum'' is not a valid Latin formation. In modern times a quorum might be defined as the minimum number of voters needed for a valid election. In ''Robert's Rules of Order'' According to Robert, each as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plenum (physics)
Luminiferous aether or ether ("luminiferous", meaning "light-bearing") was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space (a vacuum), something that waves should not be able to do. The assumption of a spatial plenum of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light. The aether hypothesis was the topic of considerable debate throughout its history, as it required the existence of an invisible and infinite material with no interaction with physical objects. As the nature of light was explored, especially in the 19th century, the physical qualities required of an aether became increasingly contradictory. By the late 1800s, the existence of the aether was being questioned, although there was no physical theory to replace it. The negative outcome of the Michelson–Morley experiment (1887) suggeste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filter (aquarium)
Aquarium filters are critical components of both freshwater and marine aquaria.Leibel WS (1993) ''A fishkeepers guide to South American cichlids.'' Tetra Press. Belgium pg 12-14. Aquarium filters remove physical and soluble chemical waste products from aquaria, simplifying maintenance. Furthermore, aquarium filters are necessary to support life as aquaria are relatively small, closed volumes of water compared to the natural environment of most fish.Sands D (1994) ''A fishkeepers guide to Central American cichlids.'' Tetra Press. Belgium pg 17-19. Overview Animals, typically fish, kept in fish tanks produce waste from excrement and respiration. Another source of waste is uneaten food or plants and fish which have died. These waste products collect in the tanks and contaminate the water. As the degree of contamination rises, the risk to the health of the aquaria increases and removal of the contamination becomes critical. Filtration is a common method used for maintenance of hea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air-mixing Plenum
In building services engineering and HVAC, an air-mixing plenum (or mixing box) is used for mixing air from different ductwork systems. Usage The most common application for an air-mixing plenum is the mixing of ''return air'' (or ''extract air'') with fresh air to provide a supply air mixture for onward distribution to the building or area which the ventilation system is serving. The air transferred from the return air stream to the supply air stream is termed ''recirculated air''. All air not mixed is rejected to the atmosphere as ''exhaust air''. Air streams are mixed to save energy and improve energy efficiency. Operation The mixing plenum normally combines two air streams, and includes for three sets of dampers: one for the fresh air, one for the exhaust air, and a mixing damper between the two air streams. The mix of fresh air and recirculated air can thus be adjusted to suit the needs of the building's occupants. Most systems will use motorized dampers to control the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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