Some standard content:
National Standard of the People's Republic of China
Symbois and units of variant quantities
Symbois and units of variant quantities This standard refers to the publications 2-1 and 27-1A of the International Electrotechnical Commission (IEC). 1 Subject matter and applicable scope
This standard specifies the symbols and units of certain characteristic values of variant quantities. GR/T14559—93
This standard applies to the occasions where the symbols and units of variant quantities are used in electricity and magnetism, and can also be used in other scientific and technological fields. Note: 1) The names of these characteristic values are not unique. 2 Reference standards
GB3102.5 Electricity and magnetism, radiation and units 3 General provisions
3.1 In various fields of science and technology, the case that changes with the change of certain quantities is called a variable (variable), and the latter is called a dependent variable. The change can be simply called a variable. The law of change of the dependent variable with the variable can be sinusoidal, sinusoidal, periodic, random or other complex laws.
Note: 1) When the square brackets are removed, it is the full name. When the square brackets and the square brackets are removed, The abbreviation is used as the abbreviation. If it does not cause confusion, the abbreviation can be used instead of the full name. Same below. 3.2 The variable is generally named according to the name of the independent variable. For example, the dependent variable that changes over time is called a time variable. 3.3 The change can often be expressed by a combination of some simple functions, such as trigonometric functions, exponential functions, distribution functions, etc., that is, the sum, product, polynomial combination of multiple denominators, etc.
3.4 This standard also has rules for some complex change bases and some function combinations. Clear! The symbols and units of some characteristic values.
3.5 The examples of several common time-dependent internal variables in the appendix of this standard are only used to illustrate the meaning and use of the symbols specified in this standard, and do not represent all situations. Www.bzxZ.net
4 Units of variable quantities
The same unit is used for the variable and the corresponding non-changing quantity. For example, the SI unit of time is still seconds and the SI unit of current is still amperes for the current whose value changes continuously over time. 5 Symbols of variable quantities
5.1 When many quantities of the same type appear in articles, formulas, charts and other situations, it is often possible to use the method of adding symbols to the symbols of the type to represent the quantities of the same type that need to be distinguished. The symbols of the same type are called body symbols: the main symbol and the additional symbol should be regarded as a whole. The additional symbol can be of the following seven types according to its relative position to the main symbol. For example: Approved by the State Administration of Technical Supervision on August 19, 1993 and implemented on February 1, 1994
GB/T 14559-93
X is the main symbol, and the symbols given in GB3102 should generally be used. The other seven are additional symbols. Among them, \1" is a left superscript.
The fold symbol ("\") is a positive superscript.
The asterisk (\*") is a right superscript. If the right superscript represents a number of power, it is called an "exponent". For this reason, except for exponents, numbers should be avoided as much as possible as right superscripts.
*2\ is a left subscript.
The curvature symbol (\～\) is a stop subscript\|| tt||The abbreviation "nax" is [right subscript. When there are many right subscript characters, they can be separated by return signs according to their meanings, such as rewriting Xalm as Xhmin
Letters with parentheses ("(t)\) are postscripts. Postscripts generally use the same font size as the main symbol, and other additional symbols use small fonts. Note: 1) Positive subscripts are used to give certain instructions to typesetters. Therefore, when using positive subscripts, typesetters should be given other instructions. Generally, positive subscripts should be used as much as possible to avoid negative numbers.
5.2 The fonts of main symbols and additional symbols should comply with the general principles of GB3101 regarding quantities, units and symbols. For example, the symbol of the physical quantity "mass" is m, the symbol of the physical quantity "force" is M, the symbol of the unit "meter\ is m, and the symbol of the word "mega" is M. 5.3 To express the changing characteristic value of a single changing quantity, multiple right subscripts 11 can be used. For example: XAEC
The right subscripts are in order. The first symbol "A" indicates the type of component, such as constant, slowly changing, alternating, etc. The second symbol "B\ specifies the specific component: the third symbol "C gives the properties associated with the component. For example: The meaning of each right subscript in Xhein or X.ai can be found in Figure B2 of Appendix B (reference). Note: 1) In addition to the subscripts mentioned in this standard that reflect the changing characteristic values of the changing quantity, the right subscript can also be used to indicate other characteristics of the quantity. For example, I is used to represent the current in a resistor.
5.4 When a quantity is decomposed into a series of components, in order to avoid an overly long right subscript in the expression of the component, a left superscript can be used to indicate the order of the components. For example:
can be replaced by
=\X, +sin(at+a)+*sin(2at+\a)+
Fg=Xac + iin(ut + an)+tsin(2t+a22)+ or
=X20+$2.1sin(ar +2g.1) + e.2sin(2at +a2.) +.5.5. The title of the quantity that changes sinusoidally
see Table 1.
General symbols (instantaneous value)
Maximum value. Amplitude
Effective value
Complex number, phase (maximum value), amplitude
Complex effective value. Effective phase
Complex instantaneous value, time-value phase
GB/T 14559
Both uppercase and lowercase letters
can be used
Use of uppercase letters is permitted
Use of lowercase letters is permitted
Note: (! When two pairs of signs are listed in parallel, they are in the same position and can be used according to the actual situation. ② Name \ Instantaneous value "and the suffix "" are used for changes at any time. ! The lower right subscript m indicates the maximum value The simplified form \max\ may also be used. 5.6 For symbols of changes other than those listed in Table 1 of 5.5, see Table 2.
General symbols (instantaneous value)
Instantaneous value
Instantaneous maximum value, amplitude
Minimum value
Peak and valley value
Mean average
Effective value
Logarithmic mean
Harmonic (reciprocal) mean
Mean absolute value, fully rectified
Absolute value
Note: Take the quantity that changes with time as an example.
When both uppercase and lowercase letters can be used
When only uppercase letters can be used
Xrain X
When two symbols separated by a slash are listed side by side, they are in equal status. You can choose according to the situation. 2B
Only lowercase letters are allowed to be used
ataln, i
GB/T 14559--93
③If there is only one maximum value for the variation within the scope of the study, the maximum value is the peak value, or the peak value is equal to the maximum value, such as the periodic quantity of a single peak. At this time, the peak value can be represented by or (X. or text). The right subscript m representing the maximum\ can also be represented by the chip formula \m\. ①If there is only one minimum value for the variation within the scope of the study, the minimum value is the valley value, or the valley value is equal to the minimum value, such as the periodic quantity of a single valley value. At this time, the valley value can be represented by ml or (X or meaning). e partial symmetry
@For the periodic quantity (taking case 1 as an example), (t)de
r2(t)dz
[区=
Where: T is the period It is a reference value.
Tla:(lde
For the quantity that changes according to the law of non-periodic function, this time needs to be indicated. 5.7 Symbols when the variable is decomposed into a series of components\See Table 3.
Constant component Constant term
Alternating component
Periodic or non-periodic slowly changing component
Maximum value of alternating component
Peak value of alternating component
Average value of alternating component after full-wave rectification
Instantaneous value
Maximum value, bat value
Effective value
Use the general symbols of components such as
Basic time value, symbol of average value Ta.ia
Symbols for the order components of Fourier series
Note: (DThis table is applicable to changes that can be decomposed into a series of components. Graphical addition symbols are used
The focus of the symbols listed in this table is the use of various additional symbols: some names are only applicable to functions that change over time. This table only takes the case where both uppercase and lowercase letters can be used as an example. ②The right subscript and b are only used as examples, that is, the two letters a and h are not limited to use. If the variable has several alternating variables or several slow variables, the virtual distinction is as follows: Im-Th*+++.
by+*Eb2**++**,
GB/T 14559—93
② The right subscripts of the solution, average, maximum, etc. of this part should be placed after the right subscript of the component, and for the sake of clarity, it is better to separate these right subscripts with commas. However, they can be separated without commas when there is no possibility of confusion. @When confusion may occur,, can be rewritten as.al. @The date of this table is to indicate the position of additional symbols. The main symbol and other additional symbols are still in accordance with the policy of 5.5. @When two symbols separated by commas are listed in parallel, They are in the same position. It can be selected according to the specific situation. 5.8 Some characteristic values of the variation of the ideal waveform with square wave and step wave as reference are shown in Table 4.
Corresponding ideal square wave and step wave transition time
(reach) stabilization time
(α+b)
Note: The maximum and minimum values of the ideal square wave and ideal step wave corresponding to the actual square wave and the actual step wave are the values that should be reached when the actual wave changes and the relatively stable stage after the change is extended to infinity. The jump value is equal to the maximum value minus the minimum value. For general cases, the maximum value is zero. If necessary, the meaning of the value equal to zero should be explained.
This change with square wave and step wave as the ideal waveform is also a change, so all the symbols in 5.6 and 5.7 can be applied. iid
Imaginary.
③The instrument is suitable for the disk that changes with time.
α and are the starting and ending times of the calculation time, the change The ratio of the solution time value to the corresponding ideal square wave, step wave combined change value. If confusion may occur, t(u) or (a5) can be used. r,trt-
-a key.
is only applicable to quantities that change with time.
The arrival time to stability is the time from the time when the change quantity passes through zero or the time specified otherwise, to the time when the change quantity just enters the range of the difference between the final value (the ideal value) and (1) and does not exceed this range again during the time studied. If (-)-, the arrival time to stability can be (±α).
If confusion may occur, t(u) or (a5) can be used.
9—93
GB/T14559
Appendix A
Example of periodic variable
(reference material)
The quantity is a constant quantity X. The synthesis of a constant variable. I--X. It.
GB/T14559-93
The quantity is the sum of an alternating variable and a, where b changes slowly and changes quickly. In this case, the slowly varying component I is also an alternating +r
GB/T14559-93
The quantity is the product of two alternating components and a, where. changes slowly and changes quickly h
CB/T1455993
The basis is a constant X. With two alternating variables., the sum.- x.+-.. h
GB/T14559--93
Figure A5a
The quantity 7 is a constant X. The algebraic sum of a constant component X and an alternating component, which is composed of a fundamental component and two modulated components Z2.T*. #-x,+r+r+
GB/T14559---93
Example of transient variable
(reference)
The quantity is the product of a changing component and a changing component 2, as shown in the figure, where the core is a component TI that decays according to the exponential law
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