Coherent System of Units (of Measurement)

2016 ◽  
Author(s):  
H. P. Lehmann ◽  
X. Fuentes-Arderiu ◽  
L. F. Bertello
Keyword(s):  
Coherent System ◽  
Units Of Measurement ◽  
System Of Units

A Simplified Presentation of Equations for the Thermodynamic Properties of Dichlorodifluoromethane, CCl2F2 (Refrigerant-12)

1969 ◽  
Vol 11 (4) ◽  
pp. 376-383
Author(s):  
R. W. Haywood
Keyword(s):  
Equation Of State ◽  
Thermodynamic Properties ◽  
Characteristic Equation ◽  
Single Phase ◽  
Saturation Pressure ◽  
Phase Region ◽  
Pure Substance ◽  
Coherent System ◽  
Saturated Liquid ◽  
System Of Units

The paper commences with a general treatment illustrating the advantages of writing the equation of state of a pure substance in characteristic (canonical or fundamental) form, from which expressions for all other thermodynamic properties can be written down in terms only of the characteristic function and its partial derivatives. In this way, thermodynamic consistency between the equations for the different properties is automatically ensured. The initial difficulties in constructing an equation of state in characteristic form are briefly discussed, and it is shown how the characteristic equation may be built up from an existing p-v-T equation of state and an equation for the specific heat capacity at zero pressure. An existing set of equations for the single-phase region of Refrigerant-12 is transformed in this way into a single characteristic equation of state from which, through given simple expressions, all other thermodynamic properties may be computed. The equation of state is expressed dimensionlessly in reduced co-ordinates so that it may be used with equal facility in any coherent system of units. For the sake of completeness, other existing equations for the saturation pressure and for the saturated liquid have been put into dimensionless form and are given in the paper.

scholarly journals Capacitance metrology at the BIPM to support National Metrology Institutes

2019 ◽  
Author(s):  
J. Angel Moreno ◽  
Pierre Gournay
Keyword(s):  
International System ◽  
International Organization ◽  
Coherent System ◽  
General Description ◽  
Fundamental Constants ◽  
Measuring Systems ◽  
Capacitance Measurements ◽  
System Of Units ◽  
The World ◽  
National Measurement

The Bureau International des Poids et Mesures (BIPM) is an international organization which works to promote and advance a coherent system of measurements throughout the world, traceable to the International System of Units (SI). One of its activities consists of the dissemination of units and the comparison of national measurement standards, which requires the availability of well-known and well-characterized standards. In particular, in the field of electricity, the BIPM supports capacitance measurements based on a quantum reference, impedance bridges and stable transfer standards, establishing traceability to the defining fundamental constants of the SI. In this paper it will be explained how the farad is realized at the BIPM, including a general description of the measuring systems, and how this unit is maintained.

scholarly journals Coherent system of units

2021 ◽  
Author(s):  
Francis Deng ◽  
Martin Vlietstra
Keyword(s):  
Coherent System ◽  
System Of Units

Systematic effects in observed parallaxes

1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson
Keyword(s):  
Error Estimates ◽  
Zero Point ◽  
Absolute Zero ◽  
Apparent Magnitude ◽  
Coherent System ◽  
Preliminary Results ◽  
General Catalogue ◽  
Systematic Effects ◽  
New Evidence ◽  
Right Ascension

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.

Dimensions of plane and solid angles and their units in the International System of Units (SI)

2020 ◽  
pp. 26-32
Author(s):  
M. I. Kalinin ◽  
L. K. Isaev ◽  
F. V. Bulygin
Keyword(s):  
Solid Angle ◽  
International System ◽  
International Committee ◽  
Plane Angle ◽  
Arc Length ◽  
Weights And Measures ◽  
International System Of Units ◽  
System Of Units ◽  
In Series ◽  
Solid Angles

The situation that has developed in the International System of Units (SI) as a result of adopting the recommendation of the International Committee of Weights and Measures (CIPM) in 1980, which proposed to consider plane and solid angles as dimensionless derived quantities, is analyzed. It is shown that the basis for such a solution was a misunderstanding of the mathematical formula relating the arc length of a circle with its radius and corresponding central angle, as well as of the expansions of trigonometric functions in series. From the analysis presented in the article, it follows that a plane angle does not depend on any of the SI quantities and should be assigned to the base quantities, and its unit, the radian, should be added to the base SI units. A solid angle, in this case, turns out to be a derived quantity of a plane angle. Its unit, the steradian, is a coherent derived unit equal to the square radian.

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