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Table 1.
The stability and accuracy of three sound travel-time estimation methods
Sound paths in
stored grain
CC
WT-CC
WT-TC
v
1
(%)
v
2
(%)
r
e
(%)
v
1
(%)
v
2
(%)
r
e
(%)
v
1
(%)
v
2
(%)
r
e
(%)
l
=1.2m,
h
=0.3m
0.25
0.18
0.17
0.25
0.19
0.35
0.09
0.06
0.12
l
=1.8m,
h
=0.3m
0.32
0.19
0.09
0.22
0.13
0.11
0.07
0.03
0.13
l
=1.2m,
h
=0.4m
0.27
0.31
0.64
0.20
0.21
0.23
0.10
0.08
0.05
l
=1.8m,
h
=0.4m
0.08
0.12
0.01
0.07
0.11
0.02
0.01
0.01
0.07
l
=1.2m,
h
=0.5m
0.11
0.08
0.12
0.10
0.07
0.02
0.09
0.03
0.16
l
=1.8m,
h
=0.5m
0.07
0.01
0.05
0.07
0.03
0.09
0.06
0.02
0.02
Average
0.183 0.148 0.180 0.152 0.123 0.137 0.070 0.038 0.092
6 Conclusion
Measuring sound travel-time accurately is the key of acoustic temperature
measurement for stored grain. The triple correlation with wavelet transform proposed
in the paper can certainly improve the SNR of sound signal by wavelet transform de-
noise and multiple correlation. The result of experiment shows that, the stability and
accuracy of WT-TC are much better than WT-CC and CC for sound travel-time
estimation in soybeans. Therefore, WT-TC is expected to use in an actual acoustic
temperature monitoring system for stored grain.
Acknowledgements.
The work is supported by Natural Science Foundation of China
(60772054), Specialized Research Fund for the Doctoral Program of Higher Education
(20102102110003) and Shenyang Science and Technology Plan (F10213100).
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