China Grid and Related Dependability Research - Grid Computing: Infrastructure, Service, and Applications - page 110

max

Ï QQ -

i i j ,

max min

if QQ - π 0

Ô

i i

, i = 1, 2 (4.26)

V = QQ

max

-

min

Ì
Ô

ij ,

i i

1 if QQ

max

-

min

= 0

Ó

i i

In Equation 4.26, Q i max and Q i min are the maximal value and the minimal
value of a quality criterion in matrix M . With Equation 4.26, we obtain a
new matrix M' :

M' = (Vi,j)2 × 4 (4.27)

The following formula is used to compute the overall quality score. The
policy that has the maximum score and with the execution time less than
the user required will be chosen by DRIC.

 2

Score P () = ( V ¥ W )

j i j , i

(4.28)

i = 1

where W j represents the weight of each criterion, and W j is computed with
the entropy method, as shown in the following equation:

W Π[0,1]

Ì

i

2

(4.29)

Ó Â

W = 1

i = 1

max( Score P ( ))

Ì

j

(4.30)

F :

T

Qj T () £

Ó

et re

where f ij is depicted as in Equation 4.31.

V

ij ,

f =

(4.31) ij ,

Â

4

V

ij ,

j = 1

 4

1

(4.32)

H =- f ln f , i = 1, 2

i i j , i j ,

ln 4

j = 1

With Equation 4.32, W i is computed as