Heuristic Scheduling Algorithm Oriented Dynamic Tasks for Imaging Satellites

Algorithm 2

The algorithm of ISDR.

(1) Set values for 𝑚, dn

(2) Set wn=0

(3) Sort dynamic task set DT according to the priorities from high to low

(4) for all 𝑖∈[1,…,dn]  do

(5) for all 𝑗∈[1,…,𝑚]  do

(6)   Compute all visible time windows of task 𝑖 observed by satellite 𝑗

(7)   Compute the number 𝑛^𝑗_𝑖 of the visible time windows of task 𝑖 observed by satellite 𝑗

(8) end for

(9) end for

(10) for all 𝑖∈[1,…,dn]  do

(11)  for all 𝑗∈[1,…,𝑚]  do

(12)    for all 𝑘∈1,…,𝑛^𝑗_𝑖  do

(13)   if 𝑤^𝑗_𝑖,𝑘 not conflict with other time windows then

(14)      Inserting 𝑤^𝑗_𝑖,𝑘 directly

(15)      goto Step  10.

(16)    end if

(17)  end for

(18) end for

(19) for all 𝑗∈[1,…,𝑚]  do

(20)   for all 𝑘∈1,…,𝑛^𝑗_𝑖  do

(21)      for all 𝑡∈[1,…,sn]  do

           if 𝑤^𝑗_𝑖,𝑘 can inserted by shifting the time window of the 𝑡th task scheduled

(22)     Insert 𝑤^𝑗_𝑖,𝑘 by shifting the time window of the 𝑡th task scheduled

(23)    goto Step  10.

(24)    end if

(25)       end for

(26)   end for

(27) end for

(28) for all 𝑗∈[1,…,𝑚]  do

(29)   for all 𝑘∈[1,…,𝑛^𝑗_𝑖]  do

(30)     for all 𝑡∈[1,…,sn]  do

(31)       if the priority of the task 𝑡 lower than the priority of task 𝑖 then

(32)       if 𝑤^𝑗_𝑖,𝑘 can be inserted by deleting the time windows of task 𝑡 then

(33)     Insert 𝑤^𝑗_𝑖,𝑘 by deleting the time windows of task 𝑡

(34)     Add the task 𝑡 to the waiting task list

(35)     wn++

(36)     goto Step  10.

(37)       end if

(38)       end if

(39)   end for

(40) end for

(41) end for

(42) end for

(43) for all 𝑖∈[1,…,wn]  do

(44)   for all 𝑗∈[1,…,𝑚]  do

(45)      for all 𝑘∈[1,…,𝑛^𝑗_𝑖,𝑘]   do

(46)         if 𝑤^𝑗_𝑖,𝑘 not conflict with other tasks scheduled then

(47)            Inserting 𝑤^𝑗_𝑖,𝑘 directly

(48)            goto Step  10

(49)         end if

(50)      end for

(51)   end for

(52) end for