Angular measure
Furman
The Furman is a unit of angular measure equal to 1⁄65,536 of a circle, or just under 20 arcseconds. It is named for Alan T. Furman, the American mathematician who adapted the CORDIC algorithm for 16-bit fixed-point arithmetic sometime around 1980.[69] 16 bits give a resolution of 216 = 65,536 distinct angles.Binary degree, binary radian, brad
A related unit of angular measure equal to 1⁄256 of a circle, represented by 8 bits, has found some use in machinery control where fine precision is not required, most notably crankshaft and camshaft position in internal combustion engine controllers, and in video game programming. There is no consensus as to its name, but it has been called the 8-Bit Furman, the Small Furman, the Furboy and more recently, the miFurman, (milli-binary-Furman). These units are convenient because they form cycles: for the 8-bit unit, the value overflows from 255 to 0 when a full circle has been traversed, so binary addition and subtraction work as expected. Measures are often made using a Gray code, which is trivially converted into more conventional notation.Grade (also grad, gradian, gon)
Coordinates were measured in grades on official French terrestrial ordnance charts from the French revolution well into the 20th century. 1 grade (or in modern symbology 1 gon) = 0.9° or 0.01 right angle. One advantage of this measure is that the distance between latitude lines 0.01 gon apart at the equator is almost exactly 1 kilometer (and would be exactly 1 km if the original definition of 1 meter = 1⁄10,000 quarter-meridian had been adhered to). One disadvantage is that common angles like 30° and 60° are expressed by fractional values (331⁄3 and 662⁄3 respectively) so this "decimal" unit failed to displace the "sexagesimal" units equilateral-vertex – degree – minute – second invented by Babylonian astronomers.Milliradian
The milliradian (mrad) is an SI derived unit defined as one thousandth of a radian, and has many useful purposes for measuring small angles. Milliradians are specifically used in optics for adjustment and range estimation, but also in general for measurement of small angles within science and technology.
The true milliradian (2000π per turn, or approximately 6283.18 per turn) must not be confused with variations such as the NATO mil (6400 per turn), the Swedish streck (6300 per turn) or the Warsaw Pact mil (6000 per turn), which are used by military organisations for range estimation and translate this map coordinates used for directing artillery fire.
MERU (Milli Earth Rate Unit)
The MERU, or Milli Earth Rate Unit, is an angular velocity equal to 1/1000 of Earth's rotation rate. It was introduced by MIT's Instrumentation Laboratories (now Draper Labs) to measure the performance of inertial navigation systems. One MERU = 7.292115×10−8 radians per second or about 0.2625 milliradians/hour.
Energy
Electronvolt mass
It is common in particle physics, where mass and energy are often interchanged, to use eV/c2, where eV (electronvolt) is the kinetic energy of an electron accelerated over one volt (1.6×10−19 joules), c is the speed of light in a vacuum (from E = mc2). This definition is intuitive for a linear particle accelerator when accelerating electrons.1 amu = 931.46 MeV/c2
Even more common is to use a system of natural units with c set to 1, and simply use eV as a unit of mass.
Gasoline gallon equivalent
In 2011 the United States Environmental Protection Agency introduced the gallon gasoline equivalent as a unit of energy because their research showed most U.S. citizens do not understand the standard units. The gallon gasoline equivalent is defined as 33.7 kWh, or about 1.213×108 joules.Efficiency or fuel economy can be given as miles per gallon gasoline equivalent.
Tons of TNT equivalent
The energy of various amounts of the explosive TNT (kiloton, megaton, gigaton) is often used as a unit of explosion energy, and sometimes of asteroid impacts and violent explosive volcanic eruptions. One ton of TNT produces 4.184×109 joules, or (by arbitrary definition) exactly 109 thermochemical calories (approximately 3.964×106 BTU). This definition is only loosely based on the actual physical properties of TNT.Hiroshima bomb and Halifax explosion
The energy released by the Hiroshima bomb explosion (about 15 kt TNT equivalent, or 6×1013 J) is often used by geologists as a unit when describing the energy of earthquakes, volcanic eruptions, and asteroid impacts.Prior to the detonation of the Hiroshima bomb, the size of the Halifax Explosion (about 3 kt TNT equivalent, or 1.26×1013 J), was the standard for this type of relative measurement. Each explosion had been the largest known man-made detonation to date.
Quad
A quad is a unit of energy equal to 1 Q = 1015 BTUs, or approximately 1.055×1018 J (slightly over one exajoule). It is suitably large to quantify energy usage by nations or by the planet as whole using everyday numbers. For example, in 2004, US energy consumption was about 100 Q/year, while demand worldwide was about 400 Q/year.Foe
A foe is a unit of energy equal to 1044 joules (≈9.478×1040 BTU) that was coined by physicist Gerry Brown of Stony Brook University. To measure the staggeringly immense amount of energy produced by a supernova, specialists occasionally use the "foe", an acronym derived from the phrase [ten to the power of] fifty-one ergs, or 1051 ergs. This unit of measure is convenient because a supernova typically releases about one foe of observable energy in a very short period of time (which can be measured in seconds).Other metric-compatible scales
The rate at which heat is removed by melting one short ton (910 kg) of ice over twenty-four hours is referred to as a ton of refrigeration, or sometimes a ton of cooling. This unit of refrigeration capacity came from the days when large blocks of ice were used for cooling, and is still used to describe the heat-removal capabilities of refrigerators and chillers today. One ton of refrigeration is equal to 12,000 BTU/h exactly, or 3.517 kW.The volume of discharge of the Amazon River sometimes used to describe large volumes of water flow such as ocean currents. The unit is equivalent to 216,000 m3/s (cumecs).
One Sverdrup (Sv) is equal to 1,000,000 cubic metres per second (264,000,000 USgal/s). It is used almost exclusively in oceanography to measure the volumetric rate of transport of ocean currents.
Energy intensity
The langley (symbol Ly) is used to measure solar radiation or insolation. It is equal to one thermochemical calorie per square centimetre (4.184×104 J/m2 or ≈3.684 BTU/sq ft) and was named after Samuel Pierpont Langley. Its symbol should not be confused with that for the light-year, ly.Kinematic viscosity
One of the few CGS units to see wider use, one stokes (symbol S or St) is a unit of kinematic viscosity, defined as 1 cm2/s, i.e., 10−4 m2/s (≈1.08×10−3 sq ft/s).Angular velocity
MERU (Milli Earth Rate Unit), an angular velocity equal to 1⁄1000 of Earth's rotation rate: 1 MERU = 0.015 degrees/hour ≈ 0.072921 microradian/second. Sometimes used to measure the angular drift rate of an inertial navigation system.Electromagnetic flux
In radio astronomy, the unit of electromagnetic flux is the jansky (symbol Jy), equivalent to 10−26 watts per square metre per hertz (= 10−26 kg/s2 in base units, about 8.8×10−31 BTU/ft2). It is named after the pioneering radio astronomer Karl Jansky. The brightest natural radio sources have flux densities of the order of one to one hundred jansky.Metre of water equivalent
A material-dependent unit used in nuclear and particle physics and engineering to measure the thickness of shielding, for example around a nuclear reactor, particle accelerator, or radiation or particle detector. 1 mwe of a material is the thickness of that material that provides the equivalent shielding of one metre (≈39.4 in) of water.This unit is commonly used in underground science to express the extent to which the overburden (usually rock) shields an underground space or laboratory from cosmic rays. The actual thickness of overburden through which cosmic rays must traverse to reach the underground space varies as a function of direction due to the shape of the overburden, which may be a mountain, or a flat plain, or something more complex like a cliff side. To express the depth of an underground space in mwe (or kmwe for deep sites) as a single number, the convention is to use the depth beneath a flat overburden at sea level that gives the same overall cosmic ray muon flux in the underground location.
Strontium unit: radiation dose
The strontium unit, formerly known as the Sunshine Unit (symbol S.U.), is a unit of biological contamination by radioactive substances (specifically strontium-90). It is equal to one picocurie of Sr-90 per gram of body calcium. Since about 2% of the human body mass is calcium, and Sr-90 has a half-life of 28.78 years, releasing 6.697+2.282 MeV per disintegration, this works out to about 1.065×10−12 grays per second. The permissible body burden was established at 1,000 S.U.Bananas, like most organic material, naturally contain a certain amount of radioactive isotopes—even in the absence of any artificial pollution or contamination. The banana equivalent dose, defined as the additional dose a person will absorb from eating one banana, expresses the severity of exposure to radiation, such as resulting from nuclear weapons or medical procedures, in terms that would make sense to most people. This is approximately 78 nanosieverts – in informal publications one often sees this estimate rounded up to 0.1 μSv.
Molar mass of cellulose
In the pulp and paper industry, molar mass is traditionally measured with a method where the intrinsic viscosity (dL/g) of the pulp sample is measured in cupriethylenediamine (Cuen). The intrinsic viscosity [η] is related to the weight-average molar mass (in daltons) by the Mark-Houwink equation: [η] = 0.070 Mw0.70. However, it is typical to cite [η] values directly in dL/g, as the "viscosity" of the cellulose, confusingly as it is not a viscosity.Iodine, bromine and kappa number
In measuring unsaturation in fatty acids, the traditional method is the iodine number. Iodine adds stoichiometrically to double bonds, so their amount is reported in grams of iodine spent per 100 grams of oil. The standard unit is a dimensionless stoichiometry ratio of moles double bonds to moles fatty acid. A similar quantity, bromine number, is used in gasoline analysis.In pulp and paper industry, a similar kappa number is used to measure how much bleaching a pulp requires. Potassium permanganate is added to react with the unsaturated compounds (lignin and uronic acids) in the pulp and back-titrated. Originally with chlorine bleaching the required quantity of chlorine could be then calculated, although modern methods use multiple stages. Since the oxidizable compounds are not exclusively lignin and the partially pulped lignin does not have a single stoichiometry, the relation between the kappa number and the precise amount of lignin is inexact.
Demography and epidemiology
Demography and quantitative epidemiology are statistical fields that deal with counts or proportions of people, or rates of change in these. Counts and proportions are technically dimensionless, and so have no units of measurement, although identifiers such as "people", "births", "infections" and the like are used for clarity. Rates of change are counts per unit of time and strictly have inverse time dimensions (per unit of time). In demography and epidemiology expressions such as "deaths per year" are used to clarify what is being measured.Prevalence, a common measure in epidemiology is strictly a type of denominator data, a dimensionless ratio or proportion. Prevalence may be expressed as a fraction, a percentage or as the number of cases per 1,000, 10,000 or 100,000 in the population of interest.
Micromort
A micromort is a unit of risk measuring a one-in-a-million probability of death (from micro- and mortality). Micromorts can be used to measure riskiness of various day-to-day activities. A microprobability is a one-in-a million chance of some event; thus a micromort is the microprobability of death. For example, smoking 1.4 cigarettes increases one's death risk by one micromort, as does traveling 370 km (230 miles) by car.To make large numbers of people comprehensible, the capacity of large stadiums is often used. Here the Melbourne Cricket Ground (MCG) is in the process of filling with 100,016 spectators on AFL grand final day in 2010.
The large numbers of people involved in demography are often difficult to comprehend. A useful visualisation tool is the audience capacity of large sports stadiums (often about 100,000). Often the capacity of the largest stadium in a region serves as a unit for a large number of people. For example, Uruguay's Estadio Centenario is often used in Uruguay, while in parts of the United States, Michigan Stadium is used in this manner. In Australia, the capacity of the Melbourne Cricket Ground (about 100,000) is often cited in this manner. Hence the Melbourne Cricket Ground serves as both a measure of people and a unit of volume.
