Publications - Faculty - Recently Submitted Faculty Publications 2008
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Ehsani - Journal of Computers and Electronics in Agriculture
Estimation of Wind Velocity Reduction through Tree Barriers using a Laser Scanning System
K. H. Lee, R. Ehsani, W. S. Castle
Abstract. The benefits of windbreaks to agriculture are great. The geometric characteristics of tree barriers play a major role in determining the performance of windbreaks. Therefore, the objectives of this study were to develop a laser scanning system for the measurement of tree geometric characteristics on-the-go and to estimate wind velocity reduction through tree barriers from the tree geometric characteristics measurements. A laser scanning system was built by mounting experimental devices (a laser sensor, a global positioning system- GPS receiver, and a notebook computer) on a test vehicle. Two tree wind barriers I and II with different porosity distributions were built by planting the trees in the barrier II more closely than the trees in the barrier I. Artificial winds generated by a blower at low and high wind velocity conditions were targeted at the centers of the tree barriers. The wind velocities were measured using a vane anemometer in four areas of the barriers, both on the windward and leeward sides. The wind velocity differences (wind velocity reductions) between the windward and leeward sides were calculated. The laser scanning system measured the tree canopy geometric characteristics in the same areas where the wind velocities were collected. The linear correlation between the tree canopy geometric characteristics and the wind velocity reductions were analyzed. In the tree wind barrier I, the highest determination coefficients (R2) of 0.9983 (root mean square deviation - RMSD = 0.0838 m s-1) and 0.9042 (RMSD = 0.8277 m s-1) were obtained at the low (<16 m s-1) and high (<20 m s-1) wind velocity conditions, respectively. On the other hand, in the tree wind barrier II, the highest R2 values of 0.9437 (RMSD=0.5131 m s-1) and 0.9270 (RMSD=0.9670 m s-1) were estimated at the low (<12 m s-1) and high (<18 m s-1) wind velocity conditions, respectively.
