Cooperative Scheduling of Imaging Observation Tasks for High-Altitude Airships Based on Propagation Algorithm

Algorithm 1

Pseudocodes of K-NGCA algorithm.

01: Initialize 𝑆={𝑆₁,𝑆₂,…,𝑆_𝑚} by Greedy algorithm;

02: Calculate 𝜎={𝜎₁,𝜎₂,…,𝜎_𝑚} by (4) and 𝑁𝑢𝑚

by (6);

03: while  𝑟𝑒𝑝<𝑀𝑎𝑥𝑁𝑢𝑚  do

04: 𝑟𝑒𝑝 ← 𝑟𝑒𝑝 + 1;

05: Let each cluster 𝑆_𝑖← 𝑁𝑈𝐿𝐿 in set 𝑆;

06: Given a vector 𝑄={𝑞₁,𝑞₂,…,𝑞_𝑛} with each

element 𝑞_𝑖←0;/*Record the element quantity of each cluster*/

07: Sort each 𝑡𝑎𝑠𝑘_𝑖 in 𝑇𝑎𝑠𝑘 by 𝑝_𝑖, and

construction a set 𝑆𝑇𝑎𝑠𝑘 to record the new task sequence;

08: for each 𝑡𝑎𝑠𝑘_𝑖∈ 𝑆𝑇𝑎𝑠𝑘 in sequence do

09:  Calculate 𝑅_𝑖={𝑟_𝑖1,𝑟_𝑖2,…,𝑟_𝑖𝑛} by (5);

10: 𝑓𝑖𝑛𝑑 ← 𝐹𝐴𝐿𝑆𝐸; 𝑠𝑡𝑒𝑝 ← 0; 𝑏𝑎𝑐𝑘𝑢𝑝 ← 𝑁𝑈𝐿𝐿;

11: while  𝑠𝑡𝑒𝑝≤𝑛  do

12:  Let 𝑣={𝑗∣𝑟_𝑖𝑗≤𝑟_𝑖𝑘,∀𝑟_𝑖𝑗,𝑟_𝑖𝑘∈𝑅_𝑖}; /*Find the nearest cluster 𝑆_𝑣*/

13:  𝑠𝑡𝑒𝑝 ← 𝑠𝑡𝑒𝑝 + 1;

14:  if  𝑅𝑃_𝑣 ≤ 𝑢_𝑖  then

15:   𝑏𝑎𝑐𝑘𝑢𝑝 ← 𝑣; 𝑓𝑖𝑛𝑑 ← 𝑇𝑅𝑈𝐸;

16:   if  𝑞_𝑣≤ 𝑁𝑢𝑚  then

17:   Add 𝑡𝑎𝑠𝑘_𝑖 to 𝑆_𝑣;

18:   𝑞_𝑣←𝑞_𝑣+1;

19:   break;

20:   end if

21:  end if

22:  𝑟_𝑖𝑣←𝑀; /*𝑀 is a tremendous number*/

23:  end while

24:  if  𝑠𝑡𝑒𝑝 > 𝑛  then

25:   if  𝑓𝑖𝑛𝑑 == 𝑇𝑅𝑈𝐸  then

26:    𝑣← 𝑏𝑎𝑐𝑘𝑢𝑝; 𝑞_𝑣←𝑞_𝑣+1;

27:    Add 𝑡𝑎𝑠𝑘_𝑖 to 𝑆_𝑣;

28:   else

29:    Reject 𝑡𝑎𝑠𝑘_𝑖 due to all HAA are invalid;

30:   end if

31:  end if

32: end for

33:  Update 𝜎={𝜎₁,𝜎₂,…,𝜎_𝑛} by (4);

34: end while