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Parts Per Notation
In science and engineering, the parts-per notation is a set of pseudo-units to describe the small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are * parts-per-million - ppm, * parts-per-billion - ppb, * parts-per-trillion - ppt, * parts-per-quadrillion - ppq, This notation is not part of the International System of Units - SI system and its meaning is ambiguous. Applications Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescein (2)
Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to Triarylmethane dye, triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is used as a fluorescent Flow tracer, tracer in many applications. The color of its aqueous solutions is green by reflection and orange by transmission (its spectral properties are dependent on pH of the solution), as can be noticed in spirit level, bubble levels, for example, in which fluorescein is added as a colorant to the Alcohol (chemistry), alcohol filling the tube in order to increase the visibility of the air bubble contained within. More concentrated solutions of fluorescein can even appear red (because under these conditions nearly all incident emission is re-absorbed by the solution). It is on the WHO Model List of Essential Medicines, World Health Organization's List of Essential Medicines. Uses Fluorescein sodium, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coefficient Of Thermal Expansion
Thermal expansion is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (usually excluding phase transitions). Substances usually contract with decreasing temperature (thermal contraction), with rare exceptions within limited temperature ranges ('' negative thermal expansion''). Temperature is a monotonic function of the average molecular kinetic energy of a substance. As energy in particles increases, they start moving faster and faster, weakening the intermolecular forces between them and therefore expanding the substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. The relative expansion (also called strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. Prediction If an equation of state is available, it can be used t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volumetric Flow Rate
In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol (sometimes \dot V). Its SI unit is cubic metres per second (m3/s). It contrasts with '' mass flow rate'', which is the other main type of fluid flow rate. In most contexts a mention of "rate of fluid flow" is likely to refer to the volumetric rate. In hydrometry, the volumetric flow rate is known as '' discharge''. The volumetric flow rate across a unit area is called '' volumetric flux'', as defined by Darcy's law and represented by the symbol . Conversely, the integration of a volumetric flux over a given area gives the volumetric flow rate. Units The SI unit is cubic metres per second (m3/s). Another unit used is standard cubic centimetres per minute (SCCM). In US customary units and imperial units, volumetric flow rate is often expressed as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metering Pump
A metering pump moves a precise volume of liquid in a specified time period providing an accurate volumetric flow rate. Delivery of fluids in precise adjustable flow rates is sometimes called metering. The term "metering pump" is based on the application or use rather than the exact kind of pump used, although a couple types of pumps are far more suitable than most other types of pumps. Although metering pumps can pump water, they are often used to pump chemicals, solutions, or other liquids. Many metering pumps are rated to be able to pump into a high discharge pressure. They are typically made to meter at flow rates which are practically constant (when averaged over time) within a wide range of discharge (outlet) pressure. Manufacturers provide each of their models of metering pumps with a maximum discharge pressure rating against which each model is guaranteed to be able to pump against. An engineer, designer, or user should ensure that the pressure and temperature rating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fahrenheit
The Fahrenheit scale () is a scale of temperature, temperature scale based on one proposed in 1724 by the German-Polish physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride (a Salt (chemistry), salt). The other limit established was his best estimate of the average human body temperature, originally set at 90 °F, then 96 °F (about 2.6 °F less than the modern value due to a later redefinition of the scale). For much of the 20th century, the Fahrenheit scale was defined by two fixed points with a 180 °F separation: the temperature at which pure water freezes was defined as 32 °F and the boiling point of water was defined to be 212 °F, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Customary Units
United States customary units form a system of measurement units commonly used in the United States and most U.S. territories since being standardized and adopted in 1832. The United States customary system developed from English units that were in use in the British Empire before the U.S. became an independent country. The United Kingdom's system of measures evolved by 1824 to create the imperial system (with imperial units), which was officially adopted in 1826, changing the definitions of some of its units. Consequently, while many U.S. units are essentially similar to their imperial counterparts, there are noticeable differences between the systems. The majority of U.S. customary units were redefined in terms of the meter and kilogram with the Mendenhall Order of 1893 and, in practice, for many years before. T.C. Mendenhall, Superintendent of Standard Weights and MeasuresOrder of April 5, 1893, published as Appendix 6 to the Report for 1893 of the United States C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inch
The inch (symbol: in or prime (symbol), ) is a Units of measurement, unit of length in the imperial units, British Imperial and the United States customary units, United States customary System of measurement, systems of measurement. It is equal to yard or of a foot (unit), foot. Derived from the Uncia (unit), Roman uncia ("twelfth"), the word ''inch'' is also sometimes used to translate similar units in other measurement systems, anthropic units, usually understood as deriving from the width of the human thumb. Standards for the exact length of an inch have varied in the past, but since the adoption of the international yard during the 1950s and 1960s the inch has been based on the metric system and defined as exactly 25.4Millimetre, mm. Name The English word "inch" () was an early borrowing from Latin ' ("one-twelfth; Roman inch; Roman ounce"). The vowel change from Latin to Old English (which became Modern English ) is known as Germanic umlaut, umlaut. The consonant c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meter
The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of a second, where the second is defined by a hyperfine transition frequency of caesium. The metre was originally defined in 1791 by the French National Assembly as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's polar circumference is approximately . In 1799, the metre was redefined in terms of a prototype metre bar. The bar used was changed in 1889, and in 1960 the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and modified slightly in 2002 to clarify that the metre is a measure of proper length. From 1983 until 2019, the metre was formally defined as the length of the path t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brass
Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic and chemical properties, but copper typically has the larger proportion, generally copper and zinc. In use since prehistoric times, it is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure. Brass is similar to bronze, a copper alloy that contains tin instead of zinc. Both bronze and brass may include small proportions of a range of other Chemical element, elements including arsenic, lead, phosphorus, aluminium, manganese and silicon. Historically, the distinction between the two alloys has been less consistent and clear, and increasingly museums use the more general term "list of copper alloys, copper alloy". Brass has long been a popular material for its bright gold-like appearance and is still used for drawer pulls and door handle, doorknobs. It has also been widely used to ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percent
In mathematics, a percentage () is a number or ratio expressed as a fraction of 100. It is often denoted using the ''percent sign'' (%), although the abbreviations ''pct.'', ''pct'', and sometimes ''pc'' are also used. A percentage is a dimensionless number (pure number), primarily used for expressing proportions, but percent is nonetheless a unit of measurement in its orthography and usage. Examples For example, 45% (read as "forty-five percent") is equal to the fraction , or 0.45. Percentages are often used to express a proportionate part of a total. (Similarly, one can also express a number as a fraction of 1,000, using the term "per mille" or the symbol "".) Example 1 If 50% of the total number of students in the class are male, that means that 50 out of every 100 students are male. If there are 500 students, then 250 of them are male. Example 2 An increase of $0.15 on a price of $2.50 is an increase by a fraction of = 0.06. Expressed as a percentage, this is a 6% ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coefficient
In mathematics, a coefficient is a Factor (arithmetic), multiplicative factor involved in some Summand, term of a polynomial, a series (mathematics), series, or any other type of expression (mathematics), expression. It may be a Dimensionless quantity, number without units, in which case it is known as a numerical factor. It may also be a constant (mathematics), constant with units of measurement, in which it is known as a constant multiplier. In general, coefficients may be any mathematical expression, expression (including Variable (mathematics), variables such as , and ). When the combination of variables and constants is not necessarily involved in a product (mathematics), product, it may be called a ''parameter''. For example, the polynomial 2x^2-x+3 has coefficients 2, −1, and 3, and the powers of the variable x in the polynomial ax^2+bx+c have coefficient parameters a, b, and c. A , also known as constant term or simply constant, is a quantity either implicitly attach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quotient
In arithmetic, a quotient (from 'how many times', pronounced ) is a quantity produced by the division of two numbers. The quotient has widespread use throughout mathematics. It has two definitions: either the integer part of a division (in the case of Euclidean division) or a fraction or ratio (in the case of a general division). For example, when dividing 20 (the ''dividend'') by 3 (the ''divisor''), the ''quotient'' is 6 (with a remainder of 2) in the first sense and 6+\tfrac=6.66... (a repeating decimal) in the second sense. In metrology (International System of Quantities and the International System of Units), "quotient" refers to the general case with respect to the units of measurement of physical quantities. ''Ratios'' is the special case for dimensionless quotients of two quantities of the same kind. Quotients with a non-trivial dimension and compound units, especially when the divisor is a duration (e.g., "per second"), are known as ''rates''. For example, densi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
