A New Method of Sound Travel-Time Measurement in Stored Grain - Advanced Research on Computer Education, Simulation and Modeling - page 232

A New Method of Sound Travel-Time Measurement in
Stored Grain
Guannan Chen, Hua Yan, Yinggang Zhou, and Lijun Liu
School of Information Science and Engineering, Shenyang University of Technology,
Shenyang 110870 , China
[e-mail],
[e-mail]
Abstract. The measurement of sound travel-time in grain bulk was researched
for monitoring grain temperature by the acoustic method. A measurement
system of sound travel-time in stored grain based on the virtual instrument was
built. A time-delay estimation method using triple correlation with wavelet
transform is proposed for solving the problem of sound attenuation in grain
bulk. Sound travel-time in soybeans was measured by the proposed method,
cross-correlation method, and cross-correlation with wavelet transform method.
The results show that the proposed method is best in measurement stability and
accuracy. Thus it is expected to be used in an actual acoustic temperature
monitoring system for stored grain.
Keywords: Acoustic temperature measurement; Stored grain; Wavelet
transform; Correlation; Virtual instrument.
1 Introduction
Stored grain is destroyed by fungi, insects and moisture. That could be reflected by
temperature of grain [1]. Grain is the poor conductor of heat, temperature monitors
must have higher spatial resolution for detecting hot spot earlier. Presently,
temperature measurement of stored grain is usually realized by contact method, and
the space resolution of temperature measurement is very low, the hot spot can't be
detected when it exist far away from contact sensors. Compared with contact method,
non-contact method is much better for stored grain temperature monitoring [2].
Acoustic temperature measurement [3] has advantages of non-contact, wide range
and large area. Sound is transmitted principally through the gas in the passageways
between the grain kernels [4]. Therefore, the research on acoustic temperature
measurement in stored grain could be available.
Sound travel-time measured accurately is very important for acoustic temperature
measurement in stored grain. As a consequence of acoustic reflection and viscosity
caused by grain kernels, the sound attenuation related to frequency obviously occur
during the propagation in grain bulk [4]. It makes the sound signal distorted that
increases the difficulty to measure the sound travel-time accurately in stored grain.