3. Unbalanced supply and demand example
Unbalanced supply and demand
If the total supply is not equal to the total demand then the problem is called unbalanced transportation problem.
It's solution :
1. If the total supply is more than the total demand, then we add a new column, with transportation cost 0
2. If the total demand is more than the total supply, then we add a new row, with transportation cost 0
Example
Find Solution using Heuristic method-1
| D1 | D2 | D3 | Supply | S1 | 4 | 8 | 8 | 76 | S2 | 16 | 24 | 16 | 82 | S3 | 8 | 16 | 24 | 77 | Demand | 72 | 102 | 41 | |
Solution: TOTAL number of supply constraints : 3 TOTAL number of demand constraints : 3 Problem Table is
| `D_1` | `D_2` | `D_3` | | Supply | `S_1` | 4 | 8 | 8 | | 76 | `S_2` | 16 | 24 | 16 | | 82 | `S_3` | 8 | 16 | 24 | | 77 | | Demand | 72 | 102 | 41 | | |
Here Total Demand = 215 is less than Total Supply = 235. So We add a dummy demand constraint with 0 unit cost and with allocation 20. Now, The modified table is
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | `S_1` | 4 | 8 | 8 | 0 | | 76 | `S_2` | 16 | 24 | 16 | 0 | | 82 | `S_3` | 8 | 16 | 24 | 0 | | 77 | | Demand | 72 | 102 | 41 | 20 | | |
Table-1
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8 | 8 | 0 | | 76 | `4=4-0` | 20 | `80=4xx20` | `S_2` | 16 | 24 | 16 | 0 | | 82 | `16=16-0` | 56 | `896=16xx56` | `S_3` | 8 | 16 | 24 | 0 | | 77 | `8=8-0` | 48 | `384=8xx48` | | Demand | 72 | 102 | 41 | 20 | | | | | | Column Penalty (P) | `4=8-4` | `8=16-8` | `8=16-8` | `0=0-0` | | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | `112=4xx28` | `384=8xx48` | `384=8xx48` | `0=0xx0` | | | | | |
The lowest PT = 0, occurs in column `D_(dummy)`.
The minimum `c_(ij)` in this column is `c_14` = 0.
The maximum allocation in this cell is min(76,20) = 20. It satisfy demand of `D_(dummy)` and adjust the supply of `S_1` from 76 to 56 (76 - 20 = 56).
Table-2
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8 | 8 | 0(20) | | 56 | `4=8-4` | 20 | `80=4xx20` | `S_2` | 16 | 24 | 16 | 0 | | 82 | `0=16-16` | 56 | `0=0xx56` | `S_3` | 8 | 16 | 24 | 0 | | 77 | `8=16-8` | 48 | `384=8xx48` | | Demand | 72 | 102 | 41 | 0 | | | | | | Column Penalty (P) | `4=8-4` | `8=16-8` | `8=16-8` | -- | | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | `112=4xx28` | `384=8xx48` | `384=8xx48` | -- | | | | | |
The lowest PT = 0, occurs in row `S_2`.
The minimum `c_(ij)` in this row is `c_21` = 16.
The maximum allocation in this cell is min(82,72) = 72. It satisfy demand of `D_1` and adjust the supply of `S_2` from 82 to 10 (82 - 72 = 10).
Table-3
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8 | 8 | 0(20) | | 56 | `0=8-8` | 20 | `0=0xx20` | `S_2` | 16(72) | 24 | 16 | 0 | | 10 | `8=24-16` | 56 | `448=8xx56` | `S_3` | 8 | 16 | 24 | 0 | | 77 | `8=24-16` | 48 | `384=8xx48` | | Demand | 0 | 102 | 41 | 0 | | | | | | Column Penalty (P) | -- | `8=16-8` | `8=16-8` | -- | | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | -- | `384=8xx48` | `384=8xx48` | -- | | | | | |
The lowest PT = 0, occurs in row `S_1`.
The minimum `c_(ij)` in this row is `c_12` = 8.
The maximum allocation in this cell is min(56,102) = 56. It satisfy supply of `S_1` and adjust the demand of `D_2` from 102 to 46 (102 - 56 = 46).
Table-4
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8(56) | 8 | 0(20) | | 0 | -- | 20 | -- | `S_2` | 16(72) | 24 | 16 | 0 | | 10 | `8=24-16` | 56 | `448=8xx56` | `S_3` | 8 | 16 | 24 | 0 | | 77 | `8=24-16` | 48 | `384=8xx48` | | Demand | 0 | 46 | 41 | 0 | | | | | | Column Penalty (P) | -- | `8=24-16` | `8=24-16` | -- | | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | -- | `384=8xx48` | `384=8xx48` | -- | | | | | |
The lowest PT = 384, occurs in row `S_3`.
The minimum `c_(ij)` in this row is `c_32` = 16.
The maximum allocation in this cell is min(77,46) = 46. It satisfy demand of `D_2` and adjust the supply of `S_3` from 77 to 31 (77 - 46 = 31).
Table-5
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8(56) | 8 | 0(20) | | 0 | -- | 20 | -- | `S_2` | 16(72) | 24 | 16 | 0 | | 10 | `16` | 56 | `896=16xx56` | `S_3` | 8 | 16(46) | 24 | 0 | | 31 | `24` | 48 | `1152=24xx48` | | Demand | 0 | 0 | 41 | 0 | | | | | | Column Penalty (P) | -- | -- | `8=24-16` | -- | | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | -- | -- | `384=8xx48` | -- | | | | | |
The lowest PT = 384, occurs in column `D_3`.
The minimum `c_(ij)` in this column is `c_23` = 16.
The maximum allocation in this cell is min(10,41) = 10. It satisfy supply of `S_2` and adjust the demand of `D_3` from 41 to 31 (41 - 10 = 31).
Table-6
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8(56) | 8 | 0(20) | | 0 | -- | 20 | -- | `S_2` | 16(72) | 24 | 16(10) | 0 | | 0 | -- | 56 | -- | `S_3` | 8 | 16(46) | 24 | 0 | | 31 | `24` | 48 | `1152=24xx48` | | Demand | 0 | 0 | 31 | 0 | | | | | | Column Penalty (P) | -- | -- | `24` | -- | | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | -- | -- | `1152=24xx48` | -- | | | | | |
The lowest PT = 1152, occurs in row `S_3`.
The minimum `c_(ij)` in this row is `c_33` = 24.
The maximum allocation in this cell is min(31,31) = 31. It satisfy supply of `S_3` and demand of `D_3`.
Initial feasible solution is
| `D_1` | `D_2` | `D_3` | `D_(dummy)` | | Supply | Row Penalty (P) | Total (T) | P`xx`T | `S_1` | 4 | 8(56) | 8 | 0(20) | | 76 | 4 | 4 | 0 | -- | -- | -- | | 20 | 80 | 80 | 0 | -- | -- | -- | | `S_2` | 16(72) | 24 | 16(10) | 0 | | 82 | 16 | 0 | 8 | 8 | 16 | -- | | 56 | 896 | 0 | 448 | 448 | 896 | -- | | `S_3` | 8 | 16(46) | 24(31) | 0 | | 77 | 8 | 8 | 8 | 8 | 24 | 24 | | 48 | 384 | 384 | 384 | 384 | 1152 | 1152 | | | Demand | 72 | 102 | 41 | 20 | | | | | | Column Penalty (P) | 4 4 -- -- -- --
| 8 8 8 8 -- --
| 8 8 8 8 8 24
| 0 -- -- -- -- --
| | | | | | Total (T) | 28 | 48 | 48 | 0 | | | | | | P`xx`T | 112 112 -- -- -- --
| 384 384 384 384 -- --
| 384 384 384 384 384 1152
| 0 -- -- -- -- --
| | | | | |
The minimum total transportation cost `= 8 xx 56 + 0 xx 20 + 16 xx 72 + 16 xx 10 + 16 xx 46 + 24 xx 31 = 3240`
Here, the number of allocated cells = 6 is equal to m + n - 1 = 3 + 4 - 1 = 6 `:.` This solution is non-degenerate
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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