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- minimal deviation from average values.
Factors and variable of condition at the same time require
the following :
- factors and variables of condition must have definition
areas given by technological or fundamental limitations (such as
technological limitations the maximum flow rate of the pump;
compressor pressure, etc.);
- between factors and variables of condition there must be
clear correspondence.
The purpose of the experiment is to get a mathematical
model of the object, which is used to optimize it (finding the
best option out of those are possible) or approximation
(approximate description of values through the others). To
obtain the mathematical model factor experiment is done. The
essence of the experiment is in consistent changing of all
factors of an object and on the study of mathematical model
(responde function) as a linear polynomial.
To simplify the calculations, values of factors are
converted into conventional units to conform numbers: -1, 0,
+1.
Conversion into conventional scale:
 Set the minimum, maximum and zero (average) value of
the factor:
Х і min, X i max, X i aver= (Х і min + X i max ) / 2 (4.2)
 set interval or step of changes h і, which is a value of
factor in natural units, adding of which to zero gives us a top
level, and subtraction gives us its lower level:
h і = X i aver- Х і min. (4.3)
 conditional values of levels of factors are calculated
(-1, 0, +1):
х i min= (Х і min - X i aver) / h і= -1, (4.4)

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