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Accelerated Aging
Accelerated aging is testing that uses aggravated conditions of heat, humidity, oxygen, sunlight, vibration, etc. to speed up the normal aging processes of items. It is used to help determine the long-term effects of expected levels of stress within a shorter time, usually in a laboratory by controlled standard test methods. It is used to estimate the useful lifespan of a product or its shelf life when actual lifespan data is unavailable. This occurs with products that have not existed long enough to have gone through their useful lifespan: for example, a new type of car engine or a new polymer for replacement joints. Physical testing or chemical testing is carried out by subjecting the product to * representative levels of stress for long time periods, * unusually high levels of stress used to accelerate the effects of natural aging, or * levels of stress that intentionally force failures (for further analysis). Mechanical parts are run at very high speed, far in excess of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climatic Chambers
Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, including the atmosphere, hydrosphere, cryosphere, lithosphere and biosphere and the interactions between them. The climate of a location is affected by its latitude, longitude, terrain, altitude, land use and nearby water bodies and their currents. Climates can be classified according to the average and typical variables, most commonly temperature and precipitation. The most widely used classification scheme is the Köppen climate classification. The Thornthwaite system, in use since 1948, incorporates evapotranspiration along with temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASTM International
ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and services. Some 12,575 apply globally. The headquarters is in West Conshohocken, Pennsylvania, about northwest of Philadelphia. It was founded in 1902 as the American Section of the International Association for Testing Materials. In addition to its traditional standards work, ASTM operates several global initiatives advancing additive manufacturing, advanced manufacturing, and emerging technologies, including the Additive Manufacturing Center of Excellence (AM CoE), the acquisition oWohlers Associatesfor market intelligence and advisory services, and the National Institute of Standards and Technology, NIST-funded Standardization Center of Excellence (SCOE). History In 1898, a group of scientists and engineers, led by chemist, industry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Product Testing
File:Consumer Reports - product testing - electric light longevity and brightness testing.tif, Testing electric light longevity and brightness testing File:Consumer Reports - product testing - television testing laboratory.tif, Television testing laboratory File:Consumer Reports - product testing - headphones in anechoic chamber.tif, Product testing headphones in an anechoic chamber Product testing, also called consumer testing or comparative testing, is a process of measuring the properties or performance of products. The theory is that since the advent of mass production, manufacturers produce branded products which they assert and advertise to be identical within some technical standard. Product testing seeks to ensure that consumers can understand what products will do for them and which products are the best value. Product testing is a strategy to increase consumer protection by checking the claims made during marketing strategy, marketing strategies such as advertising, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Engineering
Safety engineering is an engineering Branches of science, discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety engineering. Safety engineering assures that a life-critical system behaves as needed, even when components Failure, fail. Analysis techniques Analysis techniques can be split into two categories: Qualitative research, qualitative and Quantitative research, quantitative methods. Both approaches share the goal of finding causal dependencies between a hazard on system level and failures of individual components. Qualitative approaches focus on the question "What must go wrong, such that a system hazard may occur?", while quantitative methods aim at providing estimations about probabilities, rates and/or severity of consequences. The complexity of the technical systems such as Improvements of Design and Materials, Planned Inspections, Fool-pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planned Obsolescence
In economics and industrial design, planned obsolescence (also called built-in obsolescence or premature obsolescence) is the concept of policies planning or designing a good (economics), product with an artificially limited Product lifetime, useful life or a purposely frail design, so that it becomes obsolete after a certain predetermined period of time upon which it decrementally functions or suddenly ceases to function, or might be perceived as fashion, unfashionable. The rationale behind this strategy is to generate long-term sales volume by reducing the time between repeat purchases (referred to as "shortening the replacement cycle"). It is the deliberate shortening of the lifespan of a product to force people to purchase functional replacements. Planned obsolescence tends to work best when a producer has at least an oligopoly. Before introducing a planned obsolescence, the producer has to know that the customer is at least somewhat likely to buy a replacement from them in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Stress Screening
Environmental stress screening (ESS) refers to the process of exposing a newly manufactured or repaired product or component (typically electronic) to stresses such as thermal cycling and vibration in order to force latent defects to manifest themselves by permanent or catastrophic failure during the screening process. The surviving population, upon completion of screening, can be assumed to have a higher reliability than a similar unscreened population. Overview Developed to help electronics manufacturers detect product defects and production flaws, ESS is widely used in military and aerospace applications, less so for commercial products. The tests need not be elaborate, for example, switching an electronic or electrical system on and off a few times may be enough to catch some simple defects that would otherwise be encountered by the end user very soon after the product was first used. Tests typically include the following: * Temperature variations * Vibration tests * Pressu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activation Energy
In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. The activation energy (''E''a) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). Activation energy can be thought of as a magnitude of the potential barrier (sometimes called the energy barrier) separating minima of the potential energy surface pertaining to the initial and final thermodynamic state. For a chemical reaction to proceed at a reasonable rate, the temperature of the system should be high enough such that there exists an appreciable number of molecules with translational energy equal to or greater than the activation energy. The term "activation energy" was introduced in 1889 by the Swedish scientist Svante Arrhenius. Other uses Although less commonly used, activation energy also applies to nuclear reactions and various other physical phenomena. Temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Library Of Congress
The Library of Congress (LOC) is a research library in Washington, D.C., serving as the library and research service for the United States Congress and the ''de facto'' national library of the United States. It also administers Copyright law of the United States, copyright law through the United States Copyright Office, and it houses the Congressional Research Service. Founded in 1800, the Library of Congress is the oldest Cultural policy of the United States, federal cultural institution in the United States. It is housed in three buildings on Capitol Hill, adjacent to the United States Capitol, along with the National Audio-Visual Conservation Center in Culpeper, Virginia, and additional storage facilities at Fort Meade, Fort George G. Meade and Cabin Branch in Hyattsville, Maryland. The library's functions are overseen by the librarian of Congress, and its buildings are maintained by the architect of the Capitol. The LOC is one of the List of largest libraries, largest libra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arrhenius Equation
In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the Van 't Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and reverse reactions. This equation has a vast and important application in determining the rate of chemical reactions and for calculation of Activation energy, energy of activation. Arrhenius provided a physical justification and interpretation for the formula.Keith J. Laidler, Laidler, K. J. (1987) ''Chemical Kinetics'', Third Edition, Harper & Row, p. 42 Currently, it is best seen as an empirical relationship.Kenneth Connors, Chemical Kinetics, 1990, VCH Publishers It can be used to model the temperature variation of Mass diffusivity, diffusion coefficients, population of Vacancy defect, crystal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Pharmacopeia
The ''United States Pharmacopeia'' (''USP'') is a pharmacopeia (compendium of drug information) for the United States published annually by the over 200-year old United States Pharmacopeial Convention (usually also called the USP), a nonprofit organization that owns the trademark and also owns the copyright on the pharmacopeia itself. The ''USP'' is published in a combined volume with the ''National Formulary'' (a formulary) as the USP-NF. If a drug ingredient or drug product has an applicable ''USP'' quality standard (in the form of a ''USP-NF'' monograph), it must conform in order to use the designation "USP" or "NF". Drugs subject to ''USP'' standards include both human drugs ( prescription, over-the-counter, or otherwise) and animal drugs. ''USP-NF'' standards also have a role in US federal law; a drug or drug ingredient with a name recognized in ''USP-NF'' is considered adulterated if it does not satisfy compendial standards for strength, quality, or purity. USP also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
