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The time taken by the operator for informative search t і..s. (3.1), may be
determined by constructing a mathematical model of the process:
N / а  1
t i .s .  М  1 t fix . , (3.5)

where N – total volume (number of elements) of the information field;
М – number of elements that have certain sign for a search;
а – amount of information fields that may be perceived by vision;
t – time fixing information field (defined as a sum of period of indicator’s
.
fix
flashes T (T =1 / f ) and the time of his evaluation t ).
ev.
ind
ind
The value of a – is the number of elements that simultaneously enters the
zone of the observation. For angular area bounded by an angle of 10˚ to the
horizontal and vertical planes of the number of items (elements) should not exceed
8.
The dimensions of the objects, defined in angular values, are connected with
the linear dimensions by this ratio:

h  2L  tg , (3.6)
2
where L – distance from the eye to the subject;
h, α – linear and angular size of the object.
The required reliability of work of the operator is determined by the
reliability of the system that accomplishes management cycle:
n

Р  Р op  Р і (Т c ), (3.7)
c
і 1
where Р – probability of a correct solution of the problem by the operator;
op
Р (Т ) – reliability of work of the i-th machine’s link during the time Т .
і
c
c
The resultant root mean square error of the system “Human-Machine”
evaluation is defined as:
k

2
 c   2 .   m j , (3.8)
оp
j  1
where γ – random error in the operator’s action;
оp.
γ – error of j-th link of machine.
mj
Tensions activities of the operator is determined by the load coefficient η,
which should not exceed the value η=0,75 and is defined by the formula:
t
  1 not busy , (3.9)
T
a
where t not busy – time during which the operator is not busy by processing
information;
Т – total duration of alternation.
a
The efficiency of the operator is determined by the proper organization of its
mode of operation. The regimented period of rest of operator T during the
shiftwork is defined by the empirical formula, min:
Т   0 , 58Y , (3.10)

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