Environmental Engineering Reference
In-Depth Information
Step 3 Update current best chromosome based on objective value
Step 4 Check stopping criteria of GA. If any stopping criterion is satisfied, go to
Step 6; otherwise, go to Step 5
Step 5 Create new population by GA operators and go back to Step 1
Step 6 Record the current best chromosome and its corresponding objection
value and stop.
The best solution found by this solution procedure is obtained by decoding the
current best chromosome and the corresponding objection value is also yielded.
5 Case Study
Based on a case study in a container terminal in Singapore, several experiments
are conducted to see the performance of the proposed methodology to reduce
emissions of truck idling at container terminal. The emission factors are obtained
from a seaport in the U.S. (Chen et al., accepted), shown in Table
1
.
The container terminal in this case study has an entrance gate with eight lanes.
The working time at this terminal is 24 h per day. However, Table
2
shows that the
arrival rates from 10 p.m. to 5 a.m. are small. Therefore, the working time is con-
sidered 16 h per day in our experiments. The length of a period is 1 h. Typically,
it takes about 3 days for picking up all containers at a block. Thus, the maximum
number of available periods for a container is 48 periods. The service time at gate
follows an Erlang distribution where the average service time is 45 s per truck and
the degree is 4. The number of bays, number of rows, and number of tiers are var-
ied from 40 to 60, from 8 to 12, and from 5 to 7, respectively. The yard crane
gantry speed (movement from bay to bay) is 120 m/min. The yard crane trolleys
(movement from row to row) and hoists (movement from tier to tier) move with a
speed of 90 m/min and 90 m/min, respectively.
The experiment is conducted on a computer with 2.8 GHz i7-CPU and 8G
RAM. Based on the collected data, we have 9 problem instances suggested from
the manager of container terminal. These instances have the same yard crane mov-
ing speed but differ in the number of bays, the number of rows, and the number of
tiers see Table
3
for some details.
Table 1
Emission factors of truck engine idling (g/hour)
CO
2
N
2
O
CH
4
PM
10
PM
2.5
DPM
NO
X
SO
X
CO
HC
0.037
0.18
0.22
0.2
0.2
94.8
0.04
16.82
6.24
4,640
Table 2
Average arrival rates of per day (trucks per hour)
Time
00
01
02
03
04
05
06
07
08
09
10
11
7.71
7.86
11.57
8.57
12.00
19.14
59.29
74.71
97.86
87.29
97.57
79.14
Arrival rate
12
13
14
15
16
17
18
19
20
21
22
23
Time
Arrival rate
84.86
86.14
82.57
81.71
88.29
108.14
111.43
79.57
68.43
43.86
23.29
11.71
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