3Lottermoser B G.Natural enrichment of top soils with chromium and other heavy metals. Port M Acquire, New South Wales, Australia. Australian Journal of Soil Research, 1997,35:1165~ 1176.
4Wu L H, Luo Y M, Huang W R. Organo- contral for the phytoremediation of Copper polluted soil I. Release effect of dissolved organic matter and EDTA on Copper in polluted red soil. Soils, 2000, 32(20): 62~ 66.
2Sugiyamma J,Katsural T,Hong J,et al.Portable melon firm-ness tester using acoustic impulse transmission[R].Orlando,Florida:Proceedings from the sensors for nondestructive tes-ting international conference,1997.
3lava J M,Sahi S S,García-lvarez J,et a1.Use of ultra-sound for the determination of flour quality[J].Ultrasonics,2007,46(3):270-276.
4García-lvarez J,Salazar J,Rosell C M.Ultrasonic study ofwheat flour properties[J].Ultrasonics,2011,51(2):223-228.
5Harrenstein A,Brusewitz G H.Sound level measurements onflowing wheat[J].Transaction of the ASAE,1986,29(4):1114-1117.
6Brusewitz G H,Venable P B.Sound level measurements offlowing grain[J].Transaction of the ASAE,1987,30(3):863-864.
7Friesen T L,Brusewitz G H,Lowery R L.An acoustic meth-od of measuring moisture content in grain[J].Journal of Ag-ricultural Engineering Research,1988,39(1):49-56.
8Friesen T L.Developing and implementing a procedure todetermine the relationship between moisture content and a-coustic properties of flowing wheat[D].Okalahoma:Okala-homa State University,1989.
9Ruan R,Brusewitz G H.A low cost sound pressure grainmoisture transducer[J].Transaction of the ASAE,1989,32(1):316-320.
10Amoodeh M T,Khoshtaghaza M H,Minaei S.Acoustic on-line grain moisture meter[J].Computers and Electronics inAgriculture,2006,52(1):71-78.