1.
System of measurement
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A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce, systems of measurement in modern use include the metric system, the imperial system, and United States customary units. The French Revolution gave rise to the system, and this has spread around the world. In most systems, length, mass, and time are base quantities, later science developments showed that either electric charge or electric current could be added to extend the set of base quantities by which many other metrological units could be easily defined. Other quantities, such as power and speed, are derived from the set, for example. Such arrangements were satisfactory in their own contexts, the preference for a more universal and consistent system only gradually spread with the growth of science. Changing a measurement system has substantial financial and cultural costs which must be offset against the advantages to be obtained using a more rational system. However pressure built up, including scientists and engineers for conversion to a more rational. The unifying characteristic is that there was some definition based on some standard, eventually cubits and strides gave way to customary units to met the needs of merchants and scientists. In the metric system and other recent systems, a basic unit is used for each base quantity. Often secondary units are derived from the units by multiplying by powers of ten. Thus the basic unit of length is the metre, a distance of 1.234 m is 1,234 millimetres. Metrication is complete or nearly complete in almost all countries, US customary units are heavily used in the United States and to some degree in Liberia. Traditional Burmese units of measurement are used in Burma, U. S. units are used in limited contexts in Canada due to the large volume of trade, there is also considerable use of Imperial weights and measures, despite de jure Canadian conversion to metric. In the United States, metric units are used almost universally in science, widely in the military, and partially in industry, but customary units predominate in household use. At retail stores, the liter is a used unit for volume, especially on bottles of beverages. Some other standard non-SI units are still in use, such as nautical miles and knots in aviation. Metric systems of units have evolved since the adoption of the first well-defined system in France in 1795, during this evolution the use of these systems has spread throughout the world, first to non-English-speaking countries, and then to English speaking countries
2.
SI derived unit
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The International System of Units specifies a set of seven base units from which all other SI units of measurement are derived. Each of these units is either dimensionless or can be expressed as a product of powers of one or more of the base units. For example, the SI derived unit of area is the metre. The degree Celsius has an unclear status, and is arguably an exception to this rule. The names of SI units are written in lowercase, the symbols for units named after persons, however, are always written with an uppercase initial letter. In addition to the two dimensionless derived units radian and steradian,20 other derived units have special names, some other units such as the hour, litre, tonne, bar and electronvolt are not SI units, but are widely used in conjunction with SI units. Until 1995, the SI classified the radian and the steradian as supplementary units, but this designation was abandoned, International System of Quantities International System of Units International Vocabulary of Metrology Metric prefix Metric system Non-SI units mentioned in the SI Planck units SI base unit I. Mills, Tomislav Cvitas, Klaus Homann, Nikola Kallay, IUPAC, Quantities, Units and Symbols in Physical Chemistry. CS1 maint, Multiple names, authors list
3.
Mass
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In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
4.
SI base unit
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The International System of Units defines seven units of measure as a basic set from which all other SI units can be derived. The SI base units form a set of mutually independent dimensions as required by dimensional analysis commonly employed in science, thus, the kelvin, named after Lord Kelvin, has the symbol K and the ampere, named after André-Marie Ampère, has the symbol A. Many other units, such as the litre, are not part of the SI. The definitions of the units have been modified several times since the Metre Convention in 1875. Since the redefinition of the metre in 1960, the kilogram is the unit that is directly defined in terms of a physical artifact. However, the mole, the ampere, and the candela are linked through their definitions to the mass of the platinum–iridium cylinder stored in a vault near Paris. It has long been an objective in metrology to define the kilogram in terms of a fundamental constant, two possibilities have attracted particular attention, the Planck constant and the Avogadro constant. The 23rd CGPM decided to postpone any formal change until the next General Conference in 2011
5.
Kilogram
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The kilogram or kilogramme is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype of the Kilogram. The avoirdupois pound, used in both the imperial and US customary systems, is defined as exactly 0.45359237 kg, making one kilogram approximately equal to 2.2046 avoirdupois pounds. Other traditional units of weight and mass around the world are also defined in terms of the kilogram, the gram, 1/1000 of a kilogram, was provisionally defined in 1795 as the mass of one cubic centimeter of water at the melting point of ice. The final kilogram, manufactured as a prototype in 1799 and from which the IPK was derived in 1875, had an equal to the mass of 1 dm3 of water at its maximum density. The kilogram is the only SI base unit with an SI prefix as part of its name and it is also the only SI unit that is still directly defined by an artifact rather than a fundamental physical property that can be reproduced in different laboratories. Three other base units and 17 derived units in the SI system are defined relative to the kilogram, only 8 other units do not require the kilogram in their definition, temperature, time and frequency, length, and angle. At its 2011 meeting, the CGPM agreed in principle that the kilogram should be redefined in terms of the Planck constant, the decision was originally deferred until 2014, in 2014 it was deferred again until the next meeting. There are currently several different proposals for the redefinition, these are described in the Proposed Future Definitions section below, the International Prototype Kilogram is rarely used or handled. In the decree of 1795, the term gramme thus replaced gravet, the French spelling was adopted in the United Kingdom when the word was used for the first time in English in 1797, with the spelling kilogram being adopted in the United States. In the United Kingdom both spellings are used, with kilogram having become by far the more common, UK law regulating the units to be used when trading by weight or measure does not prevent the use of either spelling. In the 19th century the French word kilo, a shortening of kilogramme, was imported into the English language where it has used to mean both kilogram and kilometer. In 1935 this was adopted by the IEC as the Giorgi system, now known as MKS system. In 1948 the CGPM commissioned the CIPM to make recommendations for a practical system of units of measurement. This led to the launch of SI in 1960 and the subsequent publication of the SI Brochure, the kilogram is a unit of mass, a property which corresponds to the common perception of how heavy an object is. Mass is a property, that is, it is related to the tendency of an object at rest to remain at rest, or if in motion to remain in motion at a constant velocity. Accordingly, for astronauts in microgravity, no effort is required to hold objects off the cabin floor, they are weightless. However, since objects in microgravity still retain their mass and inertia, the ratio of the force of gravity on the two objects, measured by the scale, is equal to the ratio of their masses. On April 7,1795, the gram was decreed in France to be the weight of a volume of pure water equal to the cube of the hundredth part of the metre
6.
Imperial units
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The system of imperial units or the imperial system is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The Imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825, the system came into official use across the British Empire. The imperial system developed from what were first known as English units, the Weights and Measures Act of 1824 was initially scheduled to go into effect on 1 May 1825. However, the Weights and Measures Act of 1825 pushed back the date to 1 January 1826, the 1824 Act allowed the continued use of pre-imperial units provided that they were customary, widely known, and clearly marked with imperial equivalents. Apothecaries units are mentioned neither in the act of 1824 nor 1825, at the time, apothecaries weights and measures were regulated in England, Wales, and Berwick-upon-Tweed by the London College of Physicians, and in Ireland by the Dublin College of Physicians. In Scotland, apothecaries units were unofficially regulated by the Edinburgh College of Physicians, the three colleges published, at infrequent intervals, pharmacopoeiae, the London and Dublin editions having the force of law. The Medical Act of 1858 transferred to The Crown the right to publish the official pharmacopoeia and to regulate apothecaries weights, Metric equivalents in this article usually assume the latest official definition. Before this date, the most precise measurement of the imperial Standard Yard was 0.914398416 metres, in 1824, the various different gallons in use in the British Empire were replaced by the imperial gallon, a unit close in volume to the ale gallon. It was originally defined as the volume of 10 pounds of distilled water weighed in air with brass weights with the standing at 30 inches of mercury at a temperature of 62 °F. The Weights and Measures Act of 1985 switched to a gallon of exactly 4.54609 l and these measurements were in use from 1826, when the new imperial gallon was defined, but were officially abolished in the United Kingdom on 1 January 1971. In the USA, though no longer recommended, the system is still used occasionally in medicine. The troy pound was made the unit of mass by the 1824 Act, however, its use was abolished in the UK on 1 January 1879, with only the troy ounce. The Weights and Measures Act 1855 made the pound the primary unit of mass. In all the systems, the unit is the pound. For the yard, the length of a pendulum beating seconds at the latitude of Greenwich at Mean Sea Level in vacuo was defined as 39.01393 inches, the imperial system is one of many systems of English units. Although most of the units are defined in more than one system, some units were used to a much greater extent, or for different purposes. The distinctions between these systems are not drawn precisely. One such distinction is that between these systems and older British/English units/systems or newer additions, the US customary system is historically derived from the English units that were in use at the time of settlement
7.
United States customary units
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United States customary units are a system of measurements commonly used in the United States. The United States customary system developed from English units which were in use in the British Empire before the US declared its independence, however, the British system of measures was overhauled in 1824 to create the imperial system, changing the definitions of some units. Therefore, while many U. S. units are similar to their Imperial counterparts. The majority of U. S. customary units were redefined in terms of the meter and these definitions were refined by the international yard and pound agreement of 1959. Americans primarily use customary units in commercial activities, as well as for personal and social use, in science, medicine, many sectors of industry and some of government, metric units are used. The International System of Units, the form of the metric system, is preferred for many uses by the U. S. National Institute of Standards. The United States system of units is similar to the British imperial system, both systems are derived from English units, a system which had evolved over the millennia before American independence, and which had its roots in Roman and Anglo-Saxon units. The customary system was championed by the U. S. -based International Institute for Preserving and Perfecting Weights, advocates of the customary system saw the French Revolutionary, or metric, system as atheistic. An auxiliary of the Institute in Ohio published a poem with wording such as down with every metric scheme and A perfect inch, one adherent of the customary system called it a just weight and a just measure, which alone are acceptable to the Lord. The U. S. government passed the Metric Conversion Act of 1975, the legislation states that the federal government has a responsibility to assist industry as it voluntarily converts to the metric system, i. e. metrification. This is most evident in U. S. labeling requirements on food products, according to the CIA Factbook, the United States is one of three nations that have not adopted the metric system as their official system of weights and measures. U. S. customary units are used on consumer products. Metric units are standard in science, medicine, as well as many sectors of industry and government, the metric system also lacks a parallel to the foot. Frequently, however, these units designate quite different sizes, for example, the mile ranged by country from one-half to five U. S. miles, foot and pound also had varying definitions. Historically, a range of non-SI units were used in the U. S. and in Britain. This article deals only with the commonly used or officially defined in the U. S. For measuring length, the U. S. customary system uses the inch, foot, yard, and mile, since July 1,1959, these have been defined on the basis of 1 yard =0.9144 meters except for some applications in surveying. The U. S. the United Kingdom and other Commonwealth countries agreed on this definition, the NAD27 was replaced in the 1980s by the North American Datum of 1983, which is defined in meters
8.
International System of Units
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The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, the system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as the result of an initiative began in 1948. It is based on the system of units rather than any variant of the centimetre-gram-second system. The motivation for the development of the SI was the diversity of units that had sprung up within the CGS systems, the International System of Units has been adopted by most developed countries, however, the adoption has not been universal in all English-speaking countries. The metric system was first implemented during the French Revolution with just the metre and kilogram as standards of length, in the 1830s Carl Friedrich Gauss laid the foundations for a coherent system based on length, mass, and time. In the 1860s a group working under the auspices of the British Association for the Advancement of Science formulated the requirement for a coherent system of units with base units and derived units. Meanwhile, in 1875, the Treaty of the Metre passed responsibility for verification of the kilogram, in 1921, the Treaty was extended to include all physical quantities including electrical units originally defined in 1893. The units associated with these quantities were the metre, kilogram, second, ampere, kelvin, in 1971, a seventh base quantity, amount of substance represented by the mole, was added to the definition of SI. On 11 July 1792, the proposed the names metre, are, litre and grave for the units of length, area, capacity. The committee also proposed that multiples and submultiples of these units were to be denoted by decimal-based prefixes such as centi for a hundredth, on 10 December 1799, the law by which the metric system was to be definitively adopted in France was passed. Prior to this, the strength of the magnetic field had only been described in relative terms. The technique used by Gauss was to equate the torque induced on a magnet of known mass by the earth’s magnetic field with the torque induced on an equivalent system under gravity. The resultant calculations enabled him to assign dimensions based on mass, length, a French-inspired initiative for international cooperation in metrology led to the signing in 1875 of the Metre Convention. Initially the convention only covered standards for the metre and the kilogram, one of each was selected at random to become the International prototype metre and International prototype kilogram that replaced the mètre des Archives and kilogramme des Archives respectively. Each member state was entitled to one of each of the prototypes to serve as the national prototype for that country. Initially its prime purpose was a periodic recalibration of national prototype metres. The official language of the Metre Convention is French and the version of all official documents published by or on behalf of the CGPM is the French-language version
9.
Metric system
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The metric system is an internationally agreed decimal system of measurement. Many sources also cite Liberia and Myanmar as the other countries not to have done so. Although the originators intended to devise a system that was accessible to all. Control of the units of measure was maintained by the French government until 1875, when it was passed to an intergovernmental organisation. From its beginning, the features of the metric system were the standard set of interrelated base units. These base units are used to larger and smaller units that could replace a huge number of other units of measure in existence. Although the system was first developed for use, the development of coherent units of measure made it particularly suitable for science. Although the metric system has changed and developed since its inception, designed for transnational use, it consisted of a basic set of units of measurement, now known as base units. At the outbreak of the French Revolution in 1789, most countries, the metric system was designed to be universal—in the words of the French philosopher Marquis de Condorcet it was to be for all people for all time. However, these overtures failed and the custody of the metric system remained in the hands of the French government until 1875. In languages where the distinction is made, unit names are common nouns, the concept of using consistent classical names for the prefixes was first proposed in a report by the Commission on Weights and Measures in May 1793. The prefix kilo, for example, is used to multiply the unit by 1000, thus the kilogram and kilometre are a thousand grams and metres respectively, and a milligram and millimetre are one thousandth of a gram and metre respectively. These relations can be written symbolically as,1 mg =0, however,1935 extensions to the prefix system did not follow this convention, the prefixes nano- and micro-, for example have Greek roots. During the 19th century the prefix myria-, derived from the Greek word μύριοι, was used as a multiplier for 10000, prefixes are not usually used to indicate multiples of a second greater than 1, the non-SI units of minute, hour and day are used instead. On the other hand, prefixes are used for multiples of the unit of volume. The base units used in the system must be realisable. Each of the units in SI is accompanied by a mise en pratique published by the BIPM that describes in detail at least one way in which the base unit can be measured. In practice, such realisation is done under the auspices of a mutual acceptance arrangement, in the original version of the metric system the base units could be derived from a specified length and the weight of a specified volume of pure water
10.
Units of measurement
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A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same quantity. Any other value of quantity can be expressed as a simple multiple of the unit of measurement. For example, length is a physical quantity, the metre is a unit of length that represents a definite predetermined length. When we say 10 metres, we actually mean 10 times the definite predetermined length called metre, the definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. Different systems of units used to be very common, now there is a global standard, the International System of Units, the modern form of the metric system. In trade, weights and measures is often a subject of regulation, to ensure fairness. The International Bureau of Weights and Measures is tasked with ensuring worldwide uniformity of measurements, metrology is the science for developing nationally and internationally accepted units of weights and measures. In physics and metrology, units are standards for measurement of quantities that need clear definitions to be useful. Reproducibility of experimental results is central to the scientific method, a standard system of units facilitates this. Scientific systems of units are a refinement of the concept of weights, science, medicine, and engineering often use larger and smaller units of measurement than those used in everyday life and indicate them more precisely. The judicious selection of the units of measurement can aid researchers in problem solving, in the social sciences, there are no standard units of measurement and the theory and practice of measurement is studied in psychometrics and the theory of conjoint measurement. A unit of measurement is a quantity of a physical property. Units of measurement were among the earliest tools invented by humans, primitive societies needed rudimentary measures for many tasks, constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials. Weights and measures are mentioned in the Bible and it is a commandment to be honest and have fair measures. As of the 21st Century, multiple unit systems are used all over the world such as the United States Customary System, the British Customary System, however, the United States is the only industrialized country that has not yet completely converted to the Metric System. The systematic effort to develop an acceptable system of units dates back to 1790 when the French National Assembly charged the French Academy of Sciences to come up such a unit system. After this treaty was signed, a General Conference of Weights, the CGPM produced the current SI system which was adopted in 1954 at the 10th conference of weights and measures. Currently, the United States is a society which uses both the SI system and the US Customary system
11.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
12.
Metre
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The metre or meter, is the base unit of length in the International System of Units. The metre is defined as the length of the path travelled by light in a vacuum in 1/299792458 seconds, the metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. In 1799, it was redefined in terms of a metre bar. In 1960, the metre was redefined in terms of a number of wavelengths of a certain emission line of krypton-86. In 1983, the current definition was adopted, the imperial inch is defined as 0.0254 metres. One metre is about 3 3⁄8 inches longer than a yard, Metre is the standard spelling of the metric unit for length in nearly all English-speaking nations except the United States and the Philippines, which use meter. Measuring devices are spelled -meter in all variants of English, the suffix -meter has the same Greek origin as the unit of length. This range of uses is found in Latin, French, English. Thus calls for measurement and moderation. In 1668 the English cleric and philosopher John Wilkins proposed in an essay a decimal-based unit of length, as a result of the French Revolution, the French Academy of Sciences charged a commission with determining a single scale for all measures. In 1668, Wilkins proposed using Christopher Wrens suggestion of defining the metre using a pendulum with a length which produced a half-period of one second, christiaan Huygens had observed that length to be 38 Rijnland inches or 39.26 English inches. This is the equivalent of what is now known to be 997 mm, no official action was taken regarding this suggestion. In the 18th century, there were two approaches to the definition of the unit of length. One favoured Wilkins approach, to define the metre in terms of the length of a pendulum which produced a half-period of one second. The other approach was to define the metre as one ten-millionth of the length of a quadrant along the Earths meridian, that is, the distance from the Equator to the North Pole. This means that the quadrant would have defined as exactly 10000000 metres at that time. To establish a universally accepted foundation for the definition of the metre, more measurements of this meridian were needed. This portion of the meridian, assumed to be the length as the Paris meridian, was to serve as the basis for the length of the half meridian connecting the North Pole with the Equator
13.
Cubic centimetre
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A cubic centimetre is a commonly used unit of volume that extends the derived SI-unit cubic metre, and corresponds to the volume of a cube that measures 1 cm ×1 cm ×1 cm. One cubic centimetre corresponds to a volume of 1/1,000,000 of a metre, or 1/1,000 of a litre, or one millilitre. The mass of one centimetre of water at 3.98 °C is closely equal to one gram. Note that SI supports only the use of symbols and deprecates the use of any abbreviations for units, hence cm3 is preferred to cc or ccm. Many scientific fields have replaced cubic centimeters with milliliters, the medical and automotive fields in the United States still use the term cubic centimetre. Much of the industry outside the U. S. has switched to litres. The United Kingdom uses millilitres in preference to cubic centimetres in the medical field, most other English-speaking countries follow the UK example. There is currently a movement within the field to discontinue the use of cc in prescriptions and on medical documents. This could cause an overdose of medication, which could be dangerous or even lethal. In the United States, such confusion accounts for 12. 6% of all associated with medical abbreviations. In automobile engines, cc refers to the volume of its engine displacement in cubic centimetres. Conversions 1 millilitre =1 cm31 litre =1000 cm31 cubic inch =16.387 cm3
14.
Scientific notation
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Scientific notation is a way of expressing numbers that are too big or too small to be conveniently written in decimal form. It is commonly used by scientists, mathematicians and engineers, in part because it can simplify certain arithmetic operations, on scientific calculators it is known as SCI display mode. In scientific notation all numbers are written in the form m × 10n, where the exponent n is an integer, however, the term mantissa may cause confusion because it is the name of the fractional part of the common logarithm. If the number is then a minus sign precedes m. In normalized notation, the exponent is chosen so that the value of the coefficient is at least one. Decimal floating point is an arithmetic system closely related to scientific notation. Any given integer can be written in the form m×10^n in many ways, in normalized scientific notation, the exponent n is chosen so that the absolute value of m remains at least one but less than ten. Thus 350 is written as 3. 5×102 and this form allows easy comparison of numbers, as the exponent n gives the numbers order of magnitude. In normalized notation, the exponent n is negative for a number with absolute value between 0 and 1, the 10 and exponent are often omitted when the exponent is 0. Normalized scientific form is the form of expression of large numbers in many fields, unless an unnormalized form. Normalized scientific notation is often called exponential notation—although the latter term is general and also applies when m is not restricted to the range 1 to 10. Engineering notation differs from normalized scientific notation in that the exponent n is restricted to multiples of 3, consequently, the absolute value of m is in the range 1 ≤ |m| <1000, rather than 1 ≤ |m| <10. Though similar in concept, engineering notation is rarely called scientific notation, engineering notation allows the numbers to explicitly match their corresponding SI prefixes, which facilitates reading and oral communication. A significant figure is a digit in a number that adds to its precision and this includes all nonzero numbers, zeroes between significant digits, and zeroes indicated to be significant. Leading and trailing zeroes are not significant because they exist only to show the scale of the number. Therefore,1,230,400 usually has five significant figures,1,2,3,0, and 4, when a number is converted into normalized scientific notation, it is scaled down to a number between 1 and 10. All of the significant digits remain, but the place holding zeroes are no longer required, thus 1,230,400 would become 1.2304 ×106. However, there is also the possibility that the number may be known to six or more significant figures, thus, an additional advantage of scientific notation is that the number of significant figures is clearer
15.
International Bureau of Weights and Measures
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The organisation is usually referred to by its French initialism, BIPM. The BIPM reports to the International Committee for Weights and Measures and these organizations are also commonly referred to by their French initialisms. The BIPM was created on 20 May 1875, following the signing of the Metre Convention, under the authority of the Metric Convention, the BIPM helps to ensure uniformity of SI weights and measures around the world. It does so through a series of committees, whose members are the national metrology laboratories of the Conventions member states. The BIPM carries out measurement-related research and it takes part in and organises international comparisons of national measurement standards and performs calibrations for member states. The BIPM has an important role in maintaining accurate worldwide time of day and it combines, analyses, and averages the official atomic time standards of member nations around the world to create a single, official Coordinated Universal Time. The BIPM is also the keeper of the prototype of the kilogram. Metrologia Institute for Reference Materials and Measurements International Organization for Standardization National Institute of Standards and Technology Official website
16.
Grain (unit)
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A grain is a unit of measurement of mass, and, for the troy grain, equal to exactly 7001647989100000000♠64.79891 milligrams. It is nominally based upon the mass of a seed of a cereal. From the Bronze Age into the Renaissance the average masses of wheat, rather, expressions such as thirty-two grains of wheat, taken from the middle of the ear appear to have been ritualistic formulas, essentially the premodern equivalent of legal boilerplate. Another book states that Captain Henry Kater, of the British Standards Commission, the grain was the legal foundation of traditional English weight systems, and is the only unit that is equal throughout the troy, avoirdupois, and apothecaries systems of mass. The unit was based on the weight of a grain of barley. The fundamental unit of the pre-1527 English weight system known as Tower weights, was a different sort of known as the wheat grain. The Tower wheat grain was defined as exactly 45⁄64 of a troy grain.79891 milligrams, 7000100000000000000♠1 gram is approximately 7001154323600000000♠15.43236 grains. The unit formerly used by jewellers to measure pearls, diamonds, or other stones, called the jewellers grain or pearl grain, is equal to 1⁄4 of a carat. The grain was also the name of a traditional French unit equal to 6995531150000000000♠53.115 mg. In both British Imperial and U. S. customary units, there are precisely 7,000 grains per avoirdupois pound, the grain is commonly used to measure the mass of bullets and propellants. The term also refers to a particle of gunpowder, the size of which varies according to requirements. In archery, the grain is the unit used to weigh arrows. In dentistry, gold foil, used as a material to restore teeth, is measured in grains, in North America, the hardness of water is often measured in grains per US gallon of calcium carbonate equivalents. Otherwise, water hardness is measured in the metric unit parts per million, one grain per US gallon is approximately 6995171000000000000♠17.1 ppm. Soft water contains 1–4 gpg of calcium carbonate equivalents, while hard water contains 11–20 gpg, though no longer recommended, grains are still used occasionally in medicine as part of the apothecaries system, especially in prescriptions for older medicines such as aspirin or phenobarbital. For example, the dosage of a standard 6996325000000000000♠325 mg tablet of aspirin is sometimes given as 7000500000000000000♠5 grains, in that example the grain is approximated to 6995650000000000000♠65 mg, though the grain can also be approximated to 6995600000000000000♠60 mg, depending on the medication and manufacturer. The apothecaries system has its own system of notation, in which the symbol or abbreviation is followed by the quantity in lower case Roman numerals. For amounts less than one, the quantity is written as a fraction, or for one half, therefore, a prescription for tablets containing 325 mg of aspirin and 30 mg of codeine can be written ASA gr
17.
National Convention
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The National Convention was the third government of the French Revolution, following the two-year National Constituent Assembly and the one-year Legislative Assembly. Created after the insurrection of 10 August 1792, it was the first French government organized as a republic. The Convention sat as an assembly from 20 September 1792 to 26 October 1795. The National Convention was therefore the first French assembly elected by a suffrage without distinctions of class, although the Convention lasted until 1795, power was effectively stripped from the elected deputies and concentrated in the small Committee of Public Safety from April 1793. After the fall of Robespierre, the Convention lasted for year until a new constitution was written. The election took place from 2 to 6 September 1792 after the election of the colleges by primary assemblies on 26 August. Therefore, the increased suffrage had very little impact, the electorate returned the same sort of men that the active citizens had chosen in 1791. In the whole of France, only eleven primary assemblies wanted to retain the monarchy, of the electoral assemblies, all tacitly voted for a republic – though only Paris used the word. None of the deputies stood as a royalist for elections, out of the five million Frenchmen able to vote, only a million showed up at the polls. The Salle des Machines had galleries for the public who often influenced the debates with interruptions or applause, the members of the Convention came from all classes of society, but the most numerous were lawyers. 75 members had sat in the National Constituent Assembly,183 in the Legislative Assembly, the full number of deputies was 749, not counting 33 from the French colonies, of whom only some arrived in Paris in time. Besides these, however, the newly formed départements annexed to France from 1792 to 1795 were allowed to send deputations, according to its own ruling, the Convention elected its President every fortnight, and the outgoing President was eligible for re-election after the lapse of a fortnight. Ordinarily the sessions were held in the morning, but evening sessions also occurred frequently, sometimes in exceptional circumstances the Convention declared itself in permanent session and sat for several days without interruption. For both legislative and administrative the Convention used committees, with more or less widely extended and regulated by successive laws. The most famous of these included the Committee of Public Safety. The Convention held legislative and executive powers during the first years of the French First Republic and had three periods, Girondin, Montagnard or Jacobin, and Thermidorian. The abolition of the royalty is a matter you cannot put off till tomorrow, the first session was held on 20 September 1792. The following day, amidst profound silence, the proposition was put to the assembly, on the 22nd came the news of the Battle of Valmy
18.
Late Latin
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Late Latin is the scholarly name for the written Latin of Late Antiquity. The English dictionary definition of Late Latin dates this period from the 3rd to the 6th centuries AD and this somewhat ambiguously defined period fits between Classical Latin and Medieval Latin. Although there is no consensus about exactly when Classical Latin should end, nor exactly when Medieval Latin should begin. Being a written language, Late Latin is not identical with Vulgar Latin, the latter during those centuries served as proto-Romance, a reconstructed ancestor of the Romance languages. Although Late Latin reflects an upsurge of the use of Vulgar Latin vocabulary and constructs, it remains to a large extent classical in overall features, some are more literary and classical, some more inclined to the vernacular. Nor is Late Latin identical to Christian or patristic Latin, the writings of the early Christian fathers. While Christian writings are considered a subset of Late Latin, pagans wrote much Late Latin, serving as some sort of lingua franca to a large empire, Latin tended to become simpler, to keep above all what it had of the ordinary. Neither Late Latin nor Late Antiquity are modern terms or concepts, instances of English vernacular use of the term may also be found from the 18th century. The term Late Antiquity meaning post-classical and pre-medieval had currency in English well before then, Imperial Latin went on into English literature, Fowlers History of Roman Literature mentions it in 1903. There are, however, insoluble problems with the beginning and end of Imperial Latin, politically the excluded Augustan Period is the paradigm of imperiality, and yet the style cannot be bundled with either the Silver Age or with Late Latin. Moreover, in 6th century Italy, the Roman Empire no longer existed, subsequently the term Imperial Latin was dropped by historians of Latin literature, although it may be seen in marginal works. The Silver Age was extended a century and the four centuries represent Late Latin. Low Latin is a vague and often pejorative term that might refer to any post-classical Latin from Late Latin through Renaissance Latin depending on the author. Its origins are obscure but the Latin expression media et infima Latinitas sprang into public notice in 1678 in the title of a Glossary by Charles du Fresne, the multi-volume set had many editions and expansions by other authors subsequently. The title varies somewhat, most commonly used was Glossarium Mediae et Infimae Latinitatis and it has been translated by expressions of widely different meanings. The uncertainty is understanding what media, middle, and infima, low, the media is securely connected to Medieval Latin by Canges own terminology expounded in the Praefatio, such as scriptores mediae aetatis, writers of the middle age. Canges Glossary takes words from authors ranging from the Christian period to the Renaissance, in the former case the infimae appears extraneous, it recognizes the corruptio of the corrupta Latinitas Cange said his Glossary covered. The two-period case postulates a second unity of style, infima Latinitas, Cange in the glossarial part of his Glossary identifies some words as being used by purioris Latinitatis scriptores, such as Cicero
19.
Late antiquity
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Late antiquity is a periodization used by historians to describe the time of transition from classical antiquity to the Middle Ages in mainland Europe, the Mediterranean world, and the Near East. The development of the periodization has generally been accredited to historian Peter Brown, precise boundaries for the period are a continuing matter of debate, but Brown proposes a period between the 3rd and 8th centuries AD. Generally, it can be thought of as from the end of the Roman Empires Crisis of the Third Century to, in the East, the early Islamic period, following the Muslim conquests in the mid–7th century. In the West the end was earlier, with the start of the Early Medieval period typically placed in the 6th century, beginning with Constantine the Great, Christianity was made legal in the Empire, and a new capital was founded at Constantinople. The resultant cultural fusion of Greco-Roman, Germanic and Christian traditions formed the foundations of the subsequent culture of Europe, the term Spätantike, literally late antiquity, has been used by German-speaking historians since its popularization by Alois Riegl in the early 20th century. Concurrently, some migrating Germanic tribes such as the Ostrogoths and Visigoths saw themselves as perpetuating the Roman tradition, Constantine confirmed the legalization of the religion through the so-called Edict of Milan in 313, jointly issued with his rival in the East, Licinius. Monasticism was not the only new Christian movement to appear in Late Antiquity, notable in this regard is the topic of the Fifty Bibles of Constantine. Within the recently legitimized Christian community of the 4th century, a division could be distinctly seen between the laity and an increasingly celibate male leadership. Celibate and detached, the clergy became an elite equal in prestige to urban notables. The Late Antique period also saw a transformation of the political and social basis of life in. The later Roman Empire was in a sense a network of cities, archaeology now supplements literary sources to document the transformation followed by collapse of cities in the Mediterranean basin. Burials within the urban precincts mark another stage in dissolution of traditional urbanistic discipline, overpowered by the attraction of saintly shrines, in Roman Britain, the typical 4th- and 5th-century layer of black earth within cities seems to be a result of increased gardening in formerly urban spaces. A similar though less marked decline in population occurred later in Constantinople. In Europe there was also a decline in urban populations. As a whole, the period of antiquity was accompanied by an overall population decline in almost all Europe. Long-distance markets disappeared, and there was a reversion to a degree of local production and consumption, rather than webs of commerce. The degree and extent of discontinuity in the cities of the Greek East is a moot subject among historians. In the western Mediterranean, the new cities known to be founded in Europe between the 5th and 8th centuries were the four or five Visigothic victory cities
20.
Obol (coin)
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The obol was a form of ancient Greek currency and weight. Obols were used from early times, according to Plutarch they were originally spits of copper or bronze traded by weight, while six obols make a drachma or a handful, since that was as many as the hand could grasp. Heraklides of Pontus in his work on Etymologies mentions the obols of Heraion and this is confirmed by the historian Ephorus on his work On Inventions. Excavations at Argos discovered several dozen of these early obols, dated well before 800 BC, Plutarch states the Spartans had an iron obol of four coppers. They retained the cumbersome and impractical bars rather than proper coins to discourage the pursuit of wealth, in Classical Athens, obols were traded as silver coins. Six obols made up the drachma, there were also coins worth two obols and three obols. Each obol was divisible into eight coppers, during this era, an obol purchased a kantharos and chous of wine. Three obols was a rate for prostitutes. Legend had it that those without wealth or whose friends refused to follow proper burial rites were forced to wander the banks of the river for one hundred years. The obol or obolus was also a measurement of Greek, Roman, in ancient Greece, it was generally reckoned as 1⁄6 drachma. Under Roman rule, it was defined as 1⁄48 of a Roman ounce or about 0.57 grams, the apothecaries system also reckoned the obol or obolus as 1⁄48 ounce or 1⁄2 scruple. The obolus, along with the mirror, was a symbol of new schismatic heretics in the short story The Theologians by Argentine author Jorge Luis Borges. The currency of the United States of the Ionian Islands was called the Obol The British halfpenny, also known as the obol Obelisks. I of the Loeb Classical Library edition,1914 Plutarch, Lycurgus,9 A History of Measures The Use of Obeliskoi How we came to know about the iron obols, the antecedents of the drachma
21.
Medieval Greek
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From the 7th century onwards, Greek was the only language of administration and government in the Byzantine Empire. This stage of language is described as Byzantine Greek. The study of the Medieval Greek language and literature is a branch of Byzantine Studies, or Byzantinology, however, this approach is rather arbitrary as it is more an assumption of political as opposed to cultural and linguistic developments. Indeed, by time the spoken language, particularly pronunciation, had already shifted towards modern forms. Medieval Greek is the link between this vernacular, known as Koine Greek, and the Modern Greek language. With the transfer of the Roman imperial court to Byzantium between 324 and 330, the centre of the Roman Empire was moved into an area where Greek was the dominant language. At first, Latin remained the language of both the court and the army and it was used for documents, but its influence soon waned. From the beginning of the 6th century, amendments to the law were written in Greek. Furthermore, parts of the Roman Corpus Iuris Civilis were gradually translated into Greek, under the rule of Emperor Heraclius, who also assumed the Greek title Basileus in 629, Greek became the official language of the Eastern Roman Empire. This was in spite of the fact that the inhabitants of the empire still considered themselves Romaioi until its end in 1453, the number of those who were able to communicate in Greek may have been far higher. In any case, all cities of the Eastern Roman Empire were strongly influenced by the Greek language, alexandria, a center of Greek culture and language, fell to the Arabs in 642. During the seventh and eighth centuries, Greek was replaced by Arabic as a language in conquered territories such as Egypt. Thus, the use of Greek declined early on in Syria, Egypt, from the late 11th century onwards, the interior of Anatolia was invaded by Seljuq Turks, who advanced westwards. Language varieties after 1453 are referred to as Modern Greek, as early as in the Hellenistic period, there was a tendency towards a state of diglossia between the Attic literary language and the constantly developing vernacular Koiné. By late antiquity, the gap had become impossible to ignore, written literature reflecting this demotic Greek begins to appear around 1100. Among the preserved literature in the Attic literary language, various forms of historiography take a prominent place and they comprise chronicles as well as classicist, contemporary works of historiography, theological documents, and saints lives. Poetry can be found in the form of hymns and ecclesiastical poetry, many of the Byzantine emperors were active writers themselves and wrote chronicles or works on the running of the Byzantine state and strategic or philological works. Furthermore, letters, legal texts, and numerous registers and lists in Medieval Greek exist and these are influenced by the vernacular language of their time in choice of words and idiom, but largely follow the models of written Koine in their morphology and syntax
22.
Medieval Latin
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Despite the clerical origin of many of its authors, medieval Latin should not be confused with Ecclesiastical Latin. There is no consensus on the exact boundary where Late Latin ends. Medieval Latin had a vocabulary, which freely borrowed from other sources. Greek provided much of the vocabulary of Christianity. The various Germanic languages spoken by the Germanic tribes, who invaded southern Europe, were major sources of new words. Germanic leaders became the rulers of parts of the Roman Empire that they conquered, other more ordinary words were replaced by coinages from Vulgar Latin or Germanic sources because the classical words had fallen into disuse. Latin was also spread to such as Ireland and Germany. Works written in the lands, where Latin was a language with no relation to the local vernacular, also influenced the vocabulary. English words like abstract, subject, communicate, matter, probable, the high point of the development of medieval Latin as a literary language came with the Carolingian renaissance, a rebirth of learning kindled under the patronage of Charlemagne, king of the Franks. On the other hand, strictly speaking there was no form of medieval Latin. Every Latin author in the period spoke Latin as a second language, with varying degrees of fluency, and syntax, grammar. For instance, rather than following the classical Latin practice of placing the verb at the end. Unlike classical Latin, where esse was the auxiliary verb, medieval Latin writers might use habere as an auxiliary, similar to constructions in Germanic. The accusative and infinitive construction in classical Latin was often replaced by a clause introduced by quod or quia. This is almost identical, for example, to the use of que in similar constructions in French. In every age from the late 8th century onwards, there were learned writers who were familiar enough with classical syntax to be aware that these forms and usages were wrong, however the use of quod to introduce subordinate clauses was especially pervasive and is found at all levels. That resulted in two features of Medieval Latin compared with Classical Latin. First, many attempted to show off their knowledge of Classical Latin by using rare or archaic constructions
23.
Avoirdupois
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The avoirdupois system is a measurement system of weights which uses pounds and ounces as units. It was first commonly used in the 13th century and was updated in 1959, in 1959, by international agreement, the definitions of the pound and ounce became standardized in countries which use the pound as a unit of mass. The International Avoirdupois Pound was then created and it is the everyday system of weights used in the United States. It is still used, in varying degrees, in life in the United Kingdom, Canada. The avoirdupois weight systems general attributes were originally developed for the wool trade in the Late Middle Ages. It was historically based on a physical standardized pound or prototype weight that could be divided into 16 ounces, the use of this unofficial system gradually stabilized and evolved, with only slight changes in the reference standard or in the prototypes actual mass. Late in the 19th century various governments acted to redefine their base standards on a scientific basis, an alternative system of mass, the troy system, is generally used for precious materials. The modern definition of the pound is exactly 0.45359237 kilograms. The word avoirdupois is from Anglo-Norman French aveir de peis, literally goods of weight and this term originally referred to a class of merchandise, aveir de peis, goods of weight, things that were sold in bulk and were weighed on large steelyards or balances. Only later did the term become identified with a system of units used to weigh such merchandise. The warfare impacted orthography of the day has left many variants of the term, such as haberty-poie, there are two major hypotheses regarding the origins of the avoirdupois system. The older hypothesis is that it originated in France, a newer hypothesis is that it is based on the weight system of Florence. The avoirdupois weight system is thought to have come into use in England circa 1300 and it was originally used for weighing wool. In the early 14th century several other specialized weight systems were used, including the system of the Hanseatic League with a 16-ounce pound of 7200 grains. However, the weight system, used for coinage and for everyday use, was based on the 12-ounce tower pound of 5400 grains. The earliest known occurrence of the word avoirdupois in England is from a document entitled Tractatus de Ponderibus et Mensuris or Treatise on Weights and this document is listed in early statute books under the heading 31 Edward I dated 2 February 1303. More recent statute books list it under Statutes of uncertain date, scholars nowadays believe that it was probably written between 1266 and 1303. Initially a royal memorandum, it took on the force of law and was recognized as a statute by King Henry VIII
24.
Troy weight
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Troy weight is a system of units of mass customarily used for precious metals and gemstones. One troy ounce equals 31.1034768 grams exactly, there are only 12 troy ounces per troy pound, rather than the 16 ounces per pound found in the more common avoirdupois system. However, the pound has 7000 grains whereas the troy pound has only 5760 grains. Both systems use the same grain defined by the international yard, therefore the troy ounce is 480 grains, compared with the avoirdupois ounce, which is 437.5 grains. So the troy ounce is about 10% heavier than the avoirdupois ounce, although troy ounces are still used to weigh gold, silver, and gemstones, troy weight is no longer used in most other applications. One troy ounce of gold is denoted with the ISO4217 currency code XAU, troy weight probably takes its name from the French market town of Troyes in France where English merchants traded at least as early as the early 9th century. The name troy is first attested in 1390, describing the weight of a platter, the word troni refers to markets. Watson finds the dialect word troi, meaning a balance in Wrights Dialect Dictionary, troy weight referred to the tower system, the earliest reference to the modern troy weights is in 1414. Many aspects of the weight system were indirectly derived from the Roman monetary system. The Romans used bronze bars of varying weights as currency, an aes grave weighed 1 pound. One twelfth of an aes grave was called an uncia, or in English an ounce, before the adoption of the metric system, many systems of troy weights were in use in various parts of Europe, among them Holland troy, Paris troy, etc. Their values varied from one another by up to several percentage points, troy weights were first used in England in the 15th century, and were made official for gold and silver in 1527. The British Imperial system of weights and measures was established in 1824, the troy ounce in use today is essentially the same as the British Imperial troy ounce, adopted as an official weight standard for United States coinage by Act of Congress on May 19,1828. The British Imperial troy ounce was based on, and virtually identical with, the pre-1824 British troy ounce, the English troy ounce was officially adopted for coinage in 1527. Troy ounces have been used in England since about 1400, before that, various sorts of troy ounces were in use on the continent. The troy ounce and grain were also part of the apothecaries system and this was long used in medicine, but has now been largely replaced by the metric system. The only troy weight in widespread use today is the British Imperial troy ounce, both are currently based on a grain of 0.06479891 gram, with 480 grains to a troy ounce. The British Empire abolished the 12-ounce troy pound in the 19th century, the origin of the troy weight system is unknown
25.
Joule
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The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
26.
Chinese units of measurement
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Chinese units of measurement are the customary and traditional units of measure used in China. In the Peoples Republic of China, the units were re-standardised during the late 20th century to make them approximate SI units, many of the units were formerly based on the number 16 instead of 10. The Chinese name for most SI units is based on that of the closest traditional unit, when it is necessary to emphasize which system is used, the words market for traditional units or common/standard for SI units may be added in front of the name. SI is the system of units, but traditional units are still ubiquitously used in everyday life. Note, The names lí and fēn for small units are the same for length, area, according to the Liji, the legendary Yellow Emperor created the first measurement units. The Xiao Erya and the Kongzi Jiayu state that length units were derived from the human body, according to the Records of the Grand Historian, these human body units caused inconsistency, and Yu the Great, another legendary figure, unified the length measurements. Rulers with decimal units have been unearthed from Shang Dynasty tombs, in the Zhou Dynasty, the king conferred nobles with powers of the state and the measurement units began to be inconsistent from state to state. After the Warring States period, Qin Shi Huang unified China, in the Han Dynasty, these measurements were still being used, and were documented systematically in the Book of Han. Astronomical instruments show little change of the length of chi in the following centuries and it was not until the introduction of decimal units in the Ming Dynasty that the traditional system was revised. On 7 January 1915, the Beiyang Government promulgated a measurement law to use not only metric system as the standard, in 1976 the Hong Kong Metrication Ordinance allowed a gradual replacement of the system in favor of the International System of Units metric system. The Weights and Measures Ordinance defines the metric, Imperial, as of 2012, all three systems are legal for trade and are in widespread use. On 24 August 1992, Macau published Law No, traditional units of length include the chi, bu, and li. The precise length of these units, and the ratios between these units, has varied over time,1 bu has consisted of either 5 or 6 chi, while 1 li has consisted of 300 or 360 bu. All metric values given in the tables are exact unless otherwise specified by the approximation sign ~, certain units are also listed at List of Chinese classifiers → Measurement units. The Chinese word for metre is 米 mǐ, this can take the Chinese standard SI prefixes, a kilometre, however, may also be called 公里 gōnglǐ, i. e. a metric lǐ. For example, a kilometre is 平方公里 píngfāng gōnglǐ. These units are used to measure cereal grains, among other things, in imperial times, the physical standard for these was the jialiang. In the case of volume, the market and metric shēng coincide, the Chinese standard SI prefixes may be added to this word shēng
27.
1 yen coin
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The 1 yen coin is the smallest denomination of the Japanese yen currency. The first Japanese one yen coin was minted in 1871, and was out of silver. Eventually gold coins were also produced causing co-circulation among the two, silver one yen coins ceased production in 1914. Brass one yen coins were made in the late 1940s, the current design is made up of an aluminium alloy which has remained unchanged since the coin was first minted. In the early 2010s increasing usage of money led to a lack of demand. Like the U. S. penny, the Japanese mint has suffered due to a rising cost of the base metal it takes to produce the coins. The one yen coin is the oldest modern denomination coin, the design has remained the same since its introduction in 1955. The obverse of the coin has a figure 1 in a circle represents one yen. The reverse side has a tree, intended to symbolize the healthy growth of Japan. The first Japanese one yen coin was minted in 1870, at first these coins were minted in silver. The obverse of these featured a dragon with a circular inscription around it. The reverse had a radiant sun surrounded by a wreath, with the chrysanthemum emblem flanked by two seals of the Japanese government, the following year though Japan switched to the Gold standard in order to keep up with countries in North America, and Europe. Production of silver one yen coins was halted, and new gold coins took their place. Through 1874-1875, one-yen silver coins were minted with a new design only to be halted again sometime in 1875 in favor of Trade Dollars. Both silver and gold coins co-circulated after 1878 when Japan went with a bimetallic standard, Gold one yen coins were minted until 1880, while the silver ones lasted until 1914. Coinage was reformed in 1948 with the issue of a one yen coin,451,170,000 coins were minted until production stopped in 1950. The obverse features a numeral 1 with State of Japan above, the current design was introduced in 1955, when the first aluminium one yen coin was minted, throughout its minting history the coin was fully halted only once in 1968 due to excessive production. In 1989 a national consumption tax was put into place that calculated prices down to single-yen units, in 2011 the increasing usage of electronic money led to a lack of demand for the coin, as a result one yen coins minted until 2013 were only released in mint sets
28.
Penny (British decimal coin)
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The British decimal one penny coin, usually simply known as a penny, is a unit of currency equaling one one-hundredth of a pound sterling. Its obverse has featured the profile of Queen Elizabeth II since the introduction in 1971. Four different portraits of the Queen have been used on the coin, the second and current reverse, featuring a segment of the Royal Shield, was introduced in 2008. The correct plural form for multiple 1p coins is pennies, the correct term for monetary amounts of pennies greater than 1p is pence. The penny was minted from bronze, but since 1992 it has been minted in copper-plated steel due to the increasing price of metal. Soaring copper prices in the mid-2000s caused the value of the copper in the coins to exceed the coins face value. For example, in May 2006, the metal value of a pre-1992 1p coin was about 1.5 pence. During 2008, the value of copper fell dramatically from these peaks, as of 31 March 2014 there were an estimated 11,278 million 1p coins in circulation, with an estimated total face value of £112.787 million. The penny is the lowest value coin in circulation in the United Kingdom, to date, four different obverses have been used. In all cases, the inscription is ELIZABETH II D. G. REG. F. D,2013, where 2013 is replaced by the year of minting. In the original design both sides of the coin are encircled by dots, a feature on coins, known as beading. As with all new decimal currency, until 1984 the portrait of Queen Elizabeth II by Arnold Machin appeared on the obverse, in which the Queen wears the Girls of Great Britain, the words NEW PENNY were inscribed above the portcullis up until 1981. From 1982 the inscription changed to ONE PENNY, between 1985 and 1997 the portrait by Raphael Maklouf was used, in which the Queen wears the George IV State Diadem. In 1992 the metal used in minting this coin was switched from bronze to copper-plated steel, between 1998 and 2015 the portrait by Ian Rank-Broadley has been used, again featuring the tiara, with a signature-mark IRB below the portrait. As of June 2015, coins bearing the portrait by Jody Clark have been seen in circulation, in August 2005 the Royal Mint launched a competition to find new reverse designs for all circulating coins apart from the £2 coin. The winner, announced in April 2008, was Matthew Dent, the designs for the 1p, 2p, 5p, 10p, 20p and 50p coins depict sections of the Royal Shield that form the whole shield when placed together. The entire shield is featured on the £1 coin, the 1p coin depicts the left section between the first and third quarter of the shield, representing England and Northern Ireland. The coins obverse remains largely unchanged, but the beading, which no longer features on the reverse, has also been removed from the obverse
29.
Coins of the United States dollar
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Coins of the United States dollar were first minted in 1792. New coins have been produced annually since then and they make up an aspect of the United States currency system. Today, circulating coins exist in denominations of 1¢, 5¢, 10¢, 25¢, 50¢, also minted are bullion and commemorative coins. All of these are produced by the United States Mint, the coins are then sold to Federal Reserve Banks which in turn are responsible for putting coins into circulation and withdrawing them as demanded by the countrys economy. Today four mints operate in the United States producing billions of coins each year, the main mint is the Philadelphia Mint, which produces circulating coinage, mint sets and some commemorative coins. The Denver Mint also produces circulating coinage, mint sets and commemoratives, the San Francisco Mint produces regular and silver proof coinage, and produced circulating coinage until the 1970s. The West Point Mint produces bullion coinage, Philadelphia and Denver produce the dies used at all of the mints. The proof and mint sets are manufactured each year and contain examples of all of the circulating coins. The producing mint of each coin may be identified, as most coins bear a mint mark. The identifying letter of the mint can be found on the front side of most coins, unmarked coins are issued by the Philadelphia mint. The mass and composition of the cent changed to the current copper plated zinc core in 1982, both types were minted in 1982 with no distinguishing mark. Cents minted in 1943 were struck on planchets punched from zinc coated steel which left the resulting edges uncoated and this caused many of these coins to rust. These steel pennies are not likely to be found in circulation today, the wheat cent was mainstream and common during its time. Some dates are rare, but many can still be found in circulation, nickels produced from mid-1942 through 1945 were manufactured from 56% copper, 35% silver and 9% manganese. This allowed the saved nickel metal to be shifted to production of military supplies during World War II. Few of these are found in circulation. Prior to 1965 and passage of the Coinage Act of 1965 the composition of the dime, quarter, half-dollar and dollar coins was 90% silver, the half-dollar continued to be minted in a 40% silver-clad composition between 1965 and 1970. Dimes and quarters from before 1965 and half-dollars from before 1971 are generally not in circulation due to being removed for their silver content, in 1975 and 1976 bicentennial coinage was minted
30.
1 cent euro coin
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The 1 cent euro coin has a value of one-hundredth of a euro and is composed of copper-covered steel. The coins of every Euro country have a reverse and each has a country-specific obverse. The coin has been used since 2002 and was not redesigned in 2007 as was the case with the higher value coins, the coin dates from 2002, when euro coins and banknotes were introduced in the 12 member eurozone and its related territories. The common side was designed by Luc Luycx, a Belgian artist who won a Europe-wide competition to design the new coins. The national sides, then 15 were each designed according to national competitions, national designs were not allowed to change until the end of 2008, unless a monarch dies or abdicates. This happened in Monaco and the Vatican City resulting in three new designs in circulation, national designs have seen some changes due to new rules stating that national designs should include the name of the issuing country. The 1 to 5 cent coins however did not change, as the highlighting of the old members over the globe was so faint it was not considered worth the cost. However new national coin designs were added, in 2007 with the entry of Slovenia, in 2008 with Cyprus and Malta, in 2011 Estonia, Latvia in 2014 and Lithuania in 2015. The coins are composed of copper-covered steel, with a diameter of 16.25 mm, a 1.67 mm thickness and a mass of 2.30 grams. The coins have been used from 2002, though some are dated 1999 which is the year the euro was created as a currency, the reverse was designed by Luc Luycx and displays a globe in the bottom right. The then-fifteen members of the EU are lightly highlighted and the half of Africa. Six fine lines cut diagonally behind the globe from each side of the coin and have twelve stars at their ends, to the top left is a large number 1 followed, in smaller text, by the words Euro Cent. The designers initials, LL, appear to the right of the globe, the obverse side of the coin depends on the issuing country. All have to include stars, the engravers initials and the year of issue. New designs also have to include the name or initials of the issuing country, the side cannot repeat the denomination of the coin unless the issuing country uses an alphabet other than Latin, Austria ignores this rule, engraving EIN EURO CENT on its coins. See enlargement of the Eurozone for expected entry dates of these countries, the one and two-cent coins were initially introduced to ensure that the transition to the euro was not used as an excuse by retailers to heavily round up prices. Despite this, the coins are legal tender and produced outside these states, so if customers with one-cent coins minted elsewhere wish to pay with them. The Nederlandse Bank calculated it would save $36 million a year by not using the smaller coins, other countries such as Germany favoured retaining the coins due to retailers desire for €1.99 prices, which appear more attractive to the consumer than €2.00
31.
Conversion of units
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Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors. The process of conversion depends on the situation and the intended purpose. This may be governed by regulation, contract, technical specifications or other published standards, engineering judgment may include such factors as, The precision and accuracy of measurement and the associated uncertainty of measurement. The statistical confidence interval or tolerance interval of the initial measurement, the number of significant figures of the measurement. The intended use of the measurement including the engineering tolerances, historical definitions of the units and their derivatives used in old measurements, e. g. international foot vs. Some conversions from one system of units to another need to be exact and this is sometimes called soft conversion. It does not involve changing the configuration of the item being measured. By contrast, a conversion or an adaptive conversion may not be exactly equivalent. It changes the measurement to convenient and workable numbers and units in the new system and it sometimes involves a slightly different configuration, or size substitution, of the item. Nominal values are allowed and used. A conversion factor is used to change the units of a quantity without changing its value. The unity bracket method of unit conversion consists of a fraction in which the denominator is equal to the numerator, because of the identity property of multiplication, the value of a number will not change as long as it is multiplied by one. Also, if the numerator and denominator of a fraction are equal to each other, so as long as the numerator and denominator of the fraction are equivalent, they will not affect the value of the measured quantity. There are many applications that offer the thousands of the various units with conversions. For example, the free software movement offers a command line utility GNU units for Linux and this article gives lists of conversion factors for each of a number of physical quantities, which are listed in the index. For each physical quantity, a number of different units are shown, Conversion between units in the metric system can be discerned by their prefixes and are thus not listed in this article. Exceptions are made if the unit is known by another name. Within each table, the units are listed alphabetically, and the SI units are highlighted, notes, See Weight for detail of mass/weight distinction and conversion
32.
Orders of magnitude (mass)
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To help compare different orders of magnitude, the following lists describe various mass levels between 10−40 kg and 1053 kg. The table below is based on the kilogram, the unit of mass in the International System of Units. The kilogram is the standard unit to include an SI prefix as part of its name. The gram is an SI derived unit of mass, however, the names of all SI mass units are based on gram, rather than on kilogram, thus 103 kg is a megagram, not a kilokilogram. The tonne is a SI-compatible unit of equal to a megagram. The unit is in use for masses above about 103 kg and is often used with SI prefixes. Other units of mass are also in use, historical units include the stone, the pound, the carat, and the grain. For subatomic particles, physicists use the equivalent to the energy represented by an electronvolt. At the atomic level, chemists use the mass of one-twelfth of a carbon-12 atom, astronomers use the mass of the sun. Unlike other physical quantities, mass-energy does not have an a priori expected minimal quantity, as is the case with time or length, plancks law allows for the existence of photons with arbitrarily low energies. This series on orders of magnitude does not have a range of larger masses Mass units conversion calculator Mass units conversion calculator JavaScript
33.
Priscian
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Priscianus Caesariensis, commonly known as Priscian, was a Latin grammarian and the author of the Institutes of Grammar which was the standard textbook for the study of Latin during the Middle Ages. It also provided the raw material for the field of speculative grammar, the details of Priscians life are largely unknown. Priscian was born and raised in the North-African city of Caesarea the capital of the Roman province of Mauretania Caesariensis, according to Cassiodorus, he taught Latin at Constantinople in the early sixth century. His minor works include a panegyric to Anastasius, written about 512, in addition, the manuscripts of his Institutes contain a subscription to the effect that the work was copied by Flavius Theodorus, a clerk in the imperial secretariat. Priscians most famous work, the Institutes of Grammar, is an exposition of Latin grammar. The dedication to Julian probably indicates the consul and patrician, not the author of an epitome of Justinians Novellae. Priscians grammar is based on the works of Herodian and Apollonius. The examples it includes to illustrate the rules preserve numerous fragments from Latin authors which would otherwise have been lost, including Ennius, Pacuvius, Accius, Lucilius, Cato and Varro. But the authors whom he quotes most frequently are Virgil, and, next to him, Terence, Cicero, Plautus, then Lucan, Horace, Juvenal, Sallust, Statius, Ovid, Livy and Persius. About a thousand manuscripts exist, all derived from the copy made by Theodorus. Most copies contain only books I—XVI, these are known as the Priscianus Major. Others contain only books XVII and XVIII along with the three books to Symmachus, these are known as his work On Construction or the Priscianus Minor, a few copies contain both parts. The earliest manuscripts are from the 9th century, though a few fragments are somewhat earlier, the metre is discussed first, each verse is scanned, and each word thoroughly and instructively examined. The poem on Anastasius mentioned above, in 312 hexameters with a short iambic introduction A translation in 1087 hexameters of the geographical survey by Dionysius Periegetes. Dante places Priscian in Hell among sodomites, Prisciani institutionum grammaticalium librorum I-XVI, indices et concordantiae. Curantibus Cirilo Garcia Roman, Marco A. Gutierrez Galindo, hildesheim, New York, Olms-Weidmann,2001, ISBN9783487113081 Prisciani institutionum grammaticalium librorum XVII et XVIII, indices et concordantiae. Curantibus Cirilo Garcia Roman, Marco A. Gutierrez Galindo, Maria del Carmen Diaz de Alda Carlos, critical edition edited by Marina Passalacqua with commentary in Italian. Roma, Edizioni di storia e letteratura,1987 German Translations Schönberger, Priscians Darstellung der lateinischen Pronomina, lateinischer Text und kommentierte deutsche Übersetzung des 12
34.
Haguenau
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Haguenau is a commune in the Bas-Rhin department of France, of which it is a sub-prefecture. It is second in size in the Bas-Rhin only to Strasbourg, to the north of the town, the Forest of Haguenau is the largest undivided forest in France. Haguenau was founded by German dukes and has swapped back and forth several times between Germany and France over the centuries, with its spelling altering between Hagenau and Haguenau by the turn. It was last German at the end of World War I, Haguenau is a rapidly growing town, its population having increased from 22,644 inhabitants in 1968 to 34,891 inhabitants in 2006. Haguenaus metropolitan area has grown from 43,904 inhabitants in 1968 to 64,562 inhabitants in 2006, Haguenau dates from the beginning of the 12th century, when the German dukes of Swabia erected a hunting lodge on an island in the Moder River. The medieval King and Holy Roman Emperor Frederick I Barbarossa fortified the settlement and gave it town rights, important for further development, on the site of the hunting lodge he founded an imperial palace he regarded as his favourite residence. In this palace were preserved the Crown Jewels of the Holy Roman Empire, i. e. the jewelled crown, sceptre, imperial orb. Richard of Cornwall, King of the Romans, made it a city in 1257. Subsequently through Rudolph I of Germany Haguenau became the seat of the Landvogt of Hagenau, in the 14th century, it housed the executive council of the Decapole, a defensive and offensive association of ten German towns in Alsace against French aggression and related political instability. In the Peace of Westphalia in 1648, the Alsace was ceded to France, in 1673 King Louis XIV had the fortifications as well as the remains of the kings palace razed in order to extinguish German traditions. Haguenau was recaptured by German troops in 1675, but was again by the French two years later, when it was nearly destroyed by fire set by looting French troops. In 1871, Haguenau was ceded to the German Empire upon its victory in the Franco-Prussian War, the Haguenau Airport was built in 1916 by the German military to train fighter and bomber pilots to fight in the First World War. Hagenau was part of the briefly independent Republic of Alsace-Lorraine after World War I, in the Second World War, Germany retook the town in 1940. In November 1944 the area surrounding Haguenau was under the control of the 256th Volksgrenadier Division under the command of General Gerhard Franz, before they withdrew, the Germans demolished bridges, useful buildings, and even the town park. However, as experienced by Haguenau throughout its history, the Germans came back, most of the inhabitants fled with the assistance of the U. S. Army. The Americans launched a counterattack to retake the town. The 313th Infantry Regiment of the 79th Division was relieved by the 506th PIR of the 101st Airborne Division on 5 February 1945, the 36th Infantry Division would relieve the 101st on 23 February 1945. On March 15 the Allied Operation Undertone, an effort of the U. S
35.
Celsius
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Celsius, also known as centigrade, is a metric scale and unit of measurement for temperature. As an SI derived unit, it is used by most countries in the world and it is named after the Swedish astronomer Anders Celsius, who developed a similar temperature scale. The degree Celsius can refer to a temperature on the Celsius scale as well as a unit to indicate a temperature interval. Before being renamed to honour Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps. The scale is based on 0° for the point of water. This scale is widely taught in schools today, by international agreement the unit degree Celsius and the Celsius scale are currently defined by two different temperatures, absolute zero, and the triple point of VSMOW. This definition also precisely relates the Celsius scale to the Kelvin scale, absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C. The temperature of the point of water is defined as precisely 273.16 K at 611.657 pascals pressure. This definition fixes the magnitude of both the degree Celsius and the kelvin as precisely 1 part in 273.16 of the difference between absolute zero and the point of water. Thus, it sets the magnitude of one degree Celsius and that of one kelvin as exactly the same, additionally, it establishes the difference between the two scales null points as being precisely 273.15 degrees. In his paper Observations of two persistent degrees on a thermometer, he recounted his experiments showing that the point of ice is essentially unaffected by pressure. He also determined with precision how the boiling point of water varied as a function of atmospheric pressure. He proposed that the point of his temperature scale, being the boiling point. This pressure is known as one standard atmosphere, the BIPMs 10th General Conference on Weights and Measures later defined one standard atmosphere to equal precisely 1013250dynes per square centimetre. On 19 May 1743 he published the design of a mercury thermometer, in 1744, coincident with the death of Anders Celsius, the Swedish botanist Carolus Linnaeus reversed Celsiuss scale. In it, Linnaeus recounted the temperatures inside the orangery at the University of Uppsala Botanical Garden, since the 19th century, the scientific and thermometry communities worldwide referred to this scale as the centigrade scale. Temperatures on the scale were often reported simply as degrees or. More properly, what was defined as centigrade then would now be hectograde.2 gradians, for scientific use, Celsius is the term usually used, with centigrade otherwise continuing to be in common but decreasing use, especially in informal contexts in English-speaking countries
36.
Wayback Machine
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The Internet Archive launched the Wayback Machine in October 2001. It was set up by Brewster Kahle and Bruce Gilliat, and is maintained with content from Alexa Internet, the service enables users to see archived versions of web pages across time, which the archive calls a three dimensional index. Since 1996, the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes and it revisits sites every few weeks or months and archives a new version. Sites can also be captured on the fly by visitors who enter the sites URL into a search box, the intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down. The overall vision of the machines creators is to archive the entire Internet, the name Wayback Machine was chosen as a reference to the WABAC machine, a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show, an animated cartoon. These crawlers also respect the robots exclusion standard for websites whose owners opt for them not to appear in search results or be cached, to overcome inconsistencies in partially cached websites, Archive-It. Information had been kept on digital tape for five years, with Kahle occasionally allowing researchers, when the archive reached its fifth anniversary, it was unveiled and opened to the public in a ceremony at the University of California, Berkeley. Snapshots usually become more than six months after they are archived or, in some cases, even later. The frequency of snapshots is variable, so not all tracked website updates are recorded, Sometimes there are intervals of several weeks or years between snapshots. After August 2008 sites had to be listed on the Open Directory in order to be included. As of 2009, the Wayback Machine contained approximately three petabytes of data and was growing at a rate of 100 terabytes each month, the growth rate reported in 2003 was 12 terabytes/month, the data is stored on PetaBox rack systems manufactured by Capricorn Technologies. In 2009, the Internet Archive migrated its customized storage architecture to Sun Open Storage, in 2011 a new, improved version of the Wayback Machine, with an updated interface and fresher index of archived content, was made available for public testing. The index driving the classic Wayback Machine only has a bit of material past 2008. In January 2013, the company announced a ground-breaking milestone of 240 billion URLs, in October 2013, the company announced the Save a Page feature which allows any Internet user to archive the contents of a URL. This became a threat of abuse by the service for hosting malicious binaries, as of December 2014, the Wayback Machine contained almost nine petabytes of data and was growing at a rate of about 20 terabytes each week. Between October 2013 and March 2015 the websites global Alexa rank changed from 162 to 208, in a 2009 case, Netbula, LLC v. Chordiant Software Inc. defendant Chordiant filed a motion to compel Netbula to disable the robots. Netbula objected to the motion on the ground that defendants were asking to alter Netbulas website, in an October 2004 case, Telewizja Polska USA, Inc. v. Echostar Satellite, No.02 C3293,65 Fed. 673, a litigant attempted to use the Wayback Machine archives as a source of admissible evidence, Telewizja Polska is the provider of TVP Polonia and EchoStar operates the Dish Network
37.
International Standard Serial Number
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An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication. The ISSN is especially helpful in distinguishing between serials with the same title, ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization international standard in 1971, ISO subcommittee TC 46/SC9 is responsible for maintaining the standard. When a serial with the content is published in more than one media type. For example, many serials are published both in print and electronic media, the ISSN system refers to these types as print ISSN and electronic ISSN, respectively. The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers, as an integer number, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a check digit. Formally, the form of the ISSN code can be expressed as follows, NNNN-NNNC where N is in the set, a digit character. The ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, for calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, the modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, ISSN codes are assigned by a network of ISSN National Centres, usually located at national libraries and coordinated by the ISSN International Centre based in Paris. The International Centre is an organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, at the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept, where ISBNs are assigned to individual books, an ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an identifier associated with a serial title. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change, separate ISSNs are needed for serials in different media. Thus, the print and electronic versions of a serial need separate ISSNs. Also, a CD-ROM version and a web version of a serial require different ISSNs since two different media are involved, however, the same ISSN can be used for different file formats of the same online serial
38.
OCLC
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The Online Computer Library Center is a US-based nonprofit cooperative organization dedicated to the public purposes of furthering access to the worlds information and reducing information costs. It was founded in 1967 as the Ohio College Library Center, OCLC and its member libraries cooperatively produce and maintain WorldCat, the largest online public access catalog in the world. OCLC is funded mainly by the fees that libraries have to pay for its services, the group first met on July 5,1967 on the campus of the Ohio State University to sign the articles of incorporation for the nonprofit organization. The group hired Frederick G. Kilgour, a former Yale University medical school librarian, Kilgour wished to merge the latest information storage and retrieval system of the time, the computer, with the oldest, the library. The goal of network and database was to bring libraries together to cooperatively keep track of the worlds information in order to best serve researchers and scholars. The first library to do online cataloging through OCLC was the Alden Library at Ohio University on August 26,1971 and this was the first occurrence of online cataloging by any library worldwide. Membership in OCLC is based on use of services and contribution of data, between 1967 and 1977, OCLC membership was limited to institutions in Ohio, but in 1978, a new governance structure was established that allowed institutions from other states to join. In 2002, the structure was again modified to accommodate participation from outside the United States. As OCLC expanded services in the United States outside of Ohio, it relied on establishing strategic partnerships with networks, organizations that provided training, support, by 2008, there were 15 independent United States regional service providers. OCLC networks played a key role in OCLC governance, with networks electing delegates to serve on OCLC Members Council, in early 2009, OCLC negotiated new contracts with the former networks and opened a centralized support center. OCLC provides bibliographic, abstract and full-text information to anyone, OCLC and its member libraries cooperatively produce and maintain WorldCat—the OCLC Online Union Catalog, the largest online public access catalog in the world. WorldCat has holding records from public and private libraries worldwide. org, in October 2005, the OCLC technical staff began a wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. The Online Computer Library Center acquired the trademark and copyrights associated with the Dewey Decimal Classification System when it bought Forest Press in 1988, a browser for books with their Dewey Decimal Classifications was available until July 2013, it was replaced by the Classify Service. S. The reference management service QuestionPoint provides libraries with tools to communicate with users and this around-the-clock reference service is provided by a cooperative of participating global libraries. OCLC has produced cards for members since 1971 with its shared online catalog. OCLC commercially sells software, e. g. CONTENTdm for managing digital collections, OCLC has been conducting research for the library community for more than 30 years. In accordance with its mission, OCLC makes its research outcomes known through various publications and these publications, including journal articles, reports, newsletters, and presentations, are available through the organizations website. The most recent publications are displayed first, and all archived resources, membership Reports – A number of significant reports on topics ranging from virtual reference in libraries to perceptions about library funding
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