# International System of Units

(redirected from SI system)
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Related to SI system: English system

## In·ter·na·tion·al Sys·tem of U·nits (SI),

, Système International d'Unités (in'tĕr-na'shŭn-ăl sis'tem yū'nits, sēs-tĕm' ahn-tĕr-nahs-ē'ōn-nahl' dūn'nē-tā'),
A system of measurements, based on the metric system, adopted at the 11th General Conference on Weights and Measures of the International Organization for Standardization (1960) to cover both the coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance, respectively; supplementary units proposed include the radian (rad) for plane angle and steradian (sr) for solid angle; derived units (for example, force, power, frequency) are stated in terms of the basic units (for example, velocity is in meters per second, m s-1). Multiples (prefixes) in descending order are: exa- (E, 1018), peta- (P, 1015), tera- (T, 1012), giga- (G, 109), mega- (M, 106), kilo- (k, 103), hecto- (h, 102), deca- (da, 101), deci- (d, 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9), pico- (p, 10-12), femto- (f, 10-15), atto- (a, 10-18). Proposed prefixes are zetta- (Z, 1021), yotta- (Y, 1024), zepto- (z, 10-21), and yocto- (y, 10-24).
[Fr. Système International d'Unités]

## In·ter·na·tion·al Sys·tem of U·nits

(SI) (in'tĕr-nash'ŭn-ăl sis'tĕm yū'nits)
A system of measurements, based on the metric system, adopted at the 11th General Conference on Weights and Measures of the International Organization for Standardization (1960) to cover both the coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), Kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance; supplementary units proposed include the radian (rad) for plane angle and steradian (sr) for solid angle; derived units (e.g., force, power, frequency) are stated in terms of the basic units (e.g., velocity is in meters per second, m/sec-1). Multiples (prefixes) in descending order are: exa- (E, 1018), peta- (P, 1015), tera- (T, 1012), giga- (G, 109), mega- (M, 106), kilo- (k, 103), hecto- (h, 102), deca- (da, 101), deci- (d, 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9), pico- (p, 10-12), femto- (f, 10-15), and atto- (a, 10-18). The prefix zepto (z) has been proposed for 10-21.
[Fr. Système International d'Unités]

## In·ter·na·tion·al Sys·tem of U·nits

(SI) (in'tĕr-nash'ŭn-ăl sis'tĕm yū'nits)
System of measurements, based on the metric, to cover both coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance, respectively. Multiples (prefixes) in descending order are: exa- (E, 1018), peta- (P, 1015), tera- (T, 1012), giga- (G, 109), mega- (M, 106), kilo- (k, 103), hecto- (h, 102), deca- (da, 101), deci- (d, 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9), pico- (p, 10-12), femto- (f, 10-15), atto- (a, 10-18). Proposed prefixes are zetta- (Z, 1021), yotta- (Y, 1024), zepto- (z, 10-21), and yocto- (y, 10-24).
[Fr. Système International d'Unités]
References in periodicals archive ?
Engine Single-cylinder, four-stroke Bore (mm) 130 Stroke (mm) 140 Displacement (L) 1.87 Compression ratio 11 Power (kW) 33 Speed (rpm) 1800 [C] SAE International; Argonne National Laboratory TABLE 3 Combustion parameters for the three air-fuel ratios, IT 19 CA BTDC using SI system. Air-fuel ratio [[lambda]] 1.5 1.54 1.58 A_PP [CA ATDC] 17.1 17.7 18.2 MFB50% [CA ATDC] 15 16 17.5 A JROHR [CA ATDC] 12 13 14 A_PAOHR [CA ATDC] 3 5 7 [C] SAE International; Argonne National Laboratory TABLE 4 Instability metrics at [lambda] = 1.58 for SI and LI.
The forms and coefficients of best-fitting nonlinear models representing the dynamic behavior of the SI system are shown to be physically meaningful, that is, typical trends and intuitive relationships are preserved.
The result for these other functions is increased ambiguity and reduced confidence in the SI system (Weick, 1995), leading to the resistance to change or distrusting of information observed by Fawcett et al.
Is Europe currently using an unadulterated SI system? How about the Far East?
The consequences of limited mate availability for the evolution of SI systems were discussed by Charlesworth (1988) and Lloyd and Webb (1992), and limited mate availability has been invoked in comparisons of reproductive efficiency in dioecy versus gametophytic SI (Anderson and Stebbins 1984, 1994; Karoly 1994).
Regarding units, the International System of Units (SI) is mandated in this and all NIST publications, so you will of course see units of the SI system such as the meter (in), kilogram (kg), second (s), etc.
Being born, raised, and educated in Sweden, but having worked for the last four years as an engineer in the United States, I certainly realize the differences between the English measurement system and the SI system. It is amusing to think that anyone using the English system can think of the SI system as being illogical and inconsistent.
In SI system scenarios, LXI is an attractive alternative built upon open Ethernet standards and free from the size constraints imposed by existing bus-specific standards.
Strengthening the link of the Josephson voltage standard to the SI system was a task that has been dominated by watt balance experiments.
The SI system is configured so that the multiple nozzles point down at an angle of up to 30|degrees~.

Site: Follow: Share:
Open / Close