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Hermetically Seal
A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers but, as technology advanced, it applied to a larger category of materials, including metals, rubber, and plastics. Hermetic seals are essential to the correct and safe functionality of many electronic and healthcare products. Used technically, it is stated in conjunction with a specific test method and conditions of use. Colloquially, the exact requirements of such a seal varies with the application. Etymology The word ''hermetic'' comes from the Greek god Hermes. A hermetic seal comes from alchemy in the tradition of Hermeticism. The legendary Hermes Trismegistus supposedly invented the process of making a glass tube airtight using a secret seal. Uses Some kinds of packaging must maintain a seal against the flow of gases, for example, packaging for some foods, pharmaceuticals, chemicals, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seal (mechanical)
A seal is a device or material that helps join systems, mechanisms or other materials together by preventing leak, leakage (e.g. in a wikt:pumping, pumping system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of gaskets. The seals are installed in pumps in a wide range of industries including chemicals, water supply, paper production, food processing and many other applications. A stationary seal may also be referred to as a 'packing'. Seal types: *Induction sealing or cap sealing *Sealant, Adhesive, sealant *Bodok seal, a specialized gas sealing washer for medical applications *Bonded seal, also known as Dowty Group, Dowty seal or Dowty washer. A type of Washer (hardware), washer with integral gasket, widely used to provide a seal at the entry point of a screw or bolt *Bridgman seal, a piston sealing mechanism that creates a high pressure reservoir from a lower pressure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass
Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window panes, tableware, and optics. Some common objects made of glass are named after the material, e.g., a Tumbler (glass), "glass" for drinking, "glasses" for vision correction, and a "magnifying glass". Glass is most often formed by rapid cooling (quenching) of the Melting, molten form. Some glasses such as volcanic glass are naturally occurring, and obsidian has been used to make arrowheads and knives since the Stone Age. Archaeological evidence suggests glassmaking dates back to at least 3600 BC in Mesopotamia, Ancient Egypt, Egypt, or Syria. The earliest known glass objects were beads, perhaps created accidentally during metalworking or the production of faience, which is a form of pottery using lead glazes. Due to its ease of formability int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermostat
A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint. Thermostats are used in any device or system that heats or cools to a setpoint temperature. Examples include building heating, central heating, air conditioners, HVAC systems, water heaters, as well as kitchen equipment including ovens and refrigerators and medical and scientific incubators. In scientific literature, these devices are often broadly classified as thermostatically controlled loads (TCLs). Thermostatically controlled loads comprise roughly 50% of the overall electricity demand in the United States. A thermostat operates as a "closed loop" control device, as it seeks to reduce the error between the desired and measured temperatures. Sometimes a thermostat combines both the sensing and control action elements of a controlled system, such as in an automotive thermostat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor Electronics
A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum (typically liberated by thermionic emission) or as free electrons and ions through an ionized gas. Semiconductor devices are manufactured both as single discrete devices and as integrated circuit (IC) chips, which consist of two or more devices—which can number from the hundreds to the billions—manufactured and interconnected on a single semiconductor wafer (also called a substrate). Semiconductor materials are useful because their behavior can be easily manipulated by the deliberate addition of impurities, known as doping. Sem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landscape Lighting
Landscape lighting or garden lighting refers to the use of outdoor lighting, illumination of private gardens and public landscapes; for the enhancement and purposes of safety, nighttime aesthetics, accessibility, security, recreation and sports, and social and event uses. Light pollution is exacerbated by excessive, misdirected, or obtrusive use of light. History Early design The public landscape and gardens have been Lighting, illuminated for as long as interior building, structures have – for beauty, security, Circulation (architecture), circulation, and social occasions; since ancient times by firelight from wood, candles, and animal-plant oil fells in torches, Sconce (light fixture), sconces and lanterns. Since the 17th century's introductions of new interior illumination fuels, the technology has then been used outdoors and in gardens. As systems were developed for power delivery, Gas lighting of the 19th century and electric light of the 20th century became part of ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landscape
A landscape is the visible features of an area of land, its landforms, and how they integrate with natural or human-made features, often considered in terms of their aesthetic appeal.''New Oxford American Dictionary''. A landscape includes the physical elements of geophysically defined landforms such as mountains, hills, water bodies such as rivers, lakes, ponds and the sea, living elements of land cover including indigenous vegetation, human elements including different forms of land use, buildings, and structures, and transitory elements such as lighting and weather conditions. Combining both their physical origins and the cultural overlay of human presence, often created over millennia, landscapes reflect a living synthesis of people and place that is vital to local and national identity. The character of a landscape helps define the self-image of the people who inhabit it and a sense of place that differentiates one region from other regions. It is the dynamic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R-value (insulation)
The ''R''-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat, in the context of construction. R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux between the warmer surface and colder surface of a barrier under steady-state conditions. The measure is therefore equally relevant for lowering energy bills for heating in the winter, for cooling in the summer, and for general comfort. The ''R-value'' is the building industry term for thermal resistance "per unit area." It is sometimes denoted RSI-value if the SI units are used. An R-value can be given for a material (e.g., for polyethylene foam), or for an assembly of materials (e.g., a wall or a window). In the case of materials, it is often expressed in terms of R-value per metre. R-values are additive for layers of materials, and the higher the R-value the better th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Conductivity
The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity. For instance, metals typically have high thermal conductivity and are very efficient at conducting heat, while the opposite is true for insulating materials such as mineral wool or Styrofoam. Metals have this high thermal conductivity due to free electrons facilitating heat transfer. Correspondingly, materials of high thermal conductivity are widely used in heat sink applications, and materials of low thermal conductivity are used as thermal insulation. The reciprocal of thermal conductivity is called thermal resistivity. The defining equation for thermal conductivity is \mathbf = - k \nabla T, where \mathbf is the heat flux, k is the thermal conductivity, and \nabla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krypton
Krypton (from 'the hidden one') is a chemical element; it has symbol (chemistry), symbol Kr and atomic number 36. It is a colorless, odorless noble gas that occurs in trace element, trace amounts in the Earth's atmosphere, atmosphere and is often used with other rare gases in fluorescent lamps. Krypton is chemically inert. Krypton, like the other noble gases, is used in lighting and photography. Krypton light has many spectral lines, and krypton Plasma (physics), plasma is useful in bright, high-powered gas lasers (krypton ion laser, ion and excimer laser, excimer lasers), each of which resonates and amplifies a single spectral line. krypton fluoride laser, Krypton fluoride also makes a useful laser medium. From 1960 to 1983, the history of the metre#Krypton standard, official definition of the metre was based on the wavelength of one spectral line of krypton-86, because of the high power and relative ease of operation of krypton discharge tubes. History Krypton was discovere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argon
Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust. Nearly all argon in Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas. The name "argon" is derived from the Greek word , neuter singular form of meaning 'lazy' or 'inactive', as a reference to the fact that the element undergoes almost no chemical reactions. The complete oc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Building
Green building (also known as green construction, sustainable building, or eco-friendly building) refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's life-cycle: from planning to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the contractor, the architects, the engineers, and the client at all project stages.Yan Ji and Stellios Plainiotis (2006): Design for Sustainability. Beijing: China Architecture and Building Press. The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort. Green building also refers to saving resources to the maximum extent, including energy saving, land saving, water saving, material saving, etc., during the whole life cycle of the building, protecting the environment and reducing pollution, providing people with healthy, comfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Conservation
Energy conservation is the effort to reduce wasteful energy consumption by using fewer energy services. This can be done by using energy more effectively (using less and better sources of energy for continuous service) or changing one's behavior to use less and better source of service (for example, by driving vehicles which consume renewable energy or energy with more efficiency). Energy conservation can be achieved through efficient energy use, which has some advantages, including a reduction in greenhouse gas emissions and a smaller carbon footprint, as well as cost, water, and energy savings. Green engineering practices improve the life cycle of the components of machines which convert energy from one form into another. Energy can be conserved by reducing waste and losses, improving efficiency through technological upgrades, improving operations and maintenance, changing users' behaviors through user profiling or user activities, monitoring appliances, shifting load to o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
