Rudarski radovi br 4 2011 - Institut za rudarstvo i metalurgiju Bor

The difference in computation between<br />
the calculation for various specific α values<br />
and the calculation where α appears as<br />
parameter occurring only in the calculation<br />
of Rz29 early completion.<br />
(in comparison the Hamming distance for:<br />
Rz28+ t29<br />
and Rz26 t29<br />
This is why a slight difference occurred<br />
for the project completion.<br />
Similar calculation will be deduced for<br />
the calculation of late completion of some<br />
activities, for calculation of time reserve,<br />
etc.<br />
+ )<br />
Fig. 4. Representation of possibility function π(t)<br />
Project completion obtained by means of α<br />
intersection where concrete values were<br />
not replaced<br />
The authors of the paper have determined<br />
the time of project realization for<br />
the given example by probabilisticpossibilistic<br />
procedure according to [3].<br />
The difference of the two calculations is<br />
that when we apply the fuzzy number<br />
comparison method it is necessary to calculate<br />
the network layout only once after<br />
which the possibility function can be defined<br />
(Figure 4).<br />
When we calculate the possibility<br />
function using the probability-possibility<br />
probabilistic-possibilistic procedure, it is<br />
necessary to calculate the entire network<br />
layout several times for concrete α parameter<br />
values (α=0; 0,25; 0,50;<br />
0,75; 1,0). In other words, it is<br />
necessary to calculate the network layout<br />
for each α value twice, except for the value<br />
α=1, when it is necessary to calculate the<br />
network layout only once (Figure 5).<br />
Fig. 5 .Representation of possibiltiy function π(t)<br />
Project completion obtained by multiple<br />
calculation of network layout by means of α<br />
concrete values<br />
(α=0; α=0,25; α= 0,50; α= 0,75 ;α=1,0)<br />
CONCLUSION<br />
The procedure presented in the paper<br />
and the specific examples have illustrated<br />
the use of Possibility Theory in planning<br />
the time of facility completion. The possibility<br />
function of the project completion<br />
was determined for those respective activities<br />
of possibility function, which is known<br />
and represented by the appropriate αsections.<br />
This procedure can determine the<br />
possibility functions of execution the individual<br />
stages of the project. The fuzzy<br />
number comparison method, described in<br />
detail, was used in order to define the project<br />
completion possibility function. The<br />
illustrated example contained the total of<br />
30 general activities and the end result suggested<br />
that, compared with other methods,<br />
the authors used to apply, this procedure<br />
which offers the easiest way to the end result,<br />
particularly in the real cases<br />
when the number of activities exceeds considerably<br />
30. Establishing the data bases<br />
and their updating provides the full<br />
No 4, 2011. 167<br />
MINING ENGINEERING