طراحي ساخت و ارزيابي حسگر تركيبي مقاومت مكانيكي خاك به صورت بلادرنگ

چكيده انگليسي :

Design Construction an Evaluation of On the go Integrated Sensor for Soil Mechanical Resistance Measurement Alireza Binandeh ar binandeh@gmail com March 7 2010 Department of Agricultural Machinery Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors ahemmat@cc iut ac ir Abstract Variability of soil physical and chemical properties in different locations within a field is generally regarded as the main causes contributing to variability in crop yield High soil strength due to soil compaction has been recognized as an important negative factor in crop growth and yield By measuring spatially continuous estimates of soil bulk strength by means of sensors the soil compaction can be mapped Soil mechanical resistance measures such as cone penetration resistance can be used as indicator of soil compaction Measurement of soil mechanical resistance by a cone pentrometer is basically a stop and go insertion method which is not fast enough to obtain enough data in intensive sampling situations Generally this problem has been addressed by obtaining a large number of measurements a process that is time consuming and labor intensive In this research an integrated sensor with a global positioning system GPS capable of rapid determination of soil strength at surface layer 0 20 cm and discrete subsurface depths 20 and 30 cm was designed constructed and field evaluated The integrated sensor was consisted of vertical and horizontal sensors The mechanical resistance vertical sensor was equipped with a 60 cm diameter disk coulter a helical spring providing the disk with a downward force and an ultrasonic sensor for measuring penetrating depth of the coulter The horizontal sensor was equipped with two 30 prismatic tips having a cross sectional base area of 324 mm2 The prismatic tips at depths 20 and 30 cm were attached horizontally to two S shape load cells housed inside a box behind the sensor shank A data acquisition system with a sampling rate of 10 Hz was used to collect the data The integrated sensor was tested in a field with silty clay loam soil at two moisture contents mcs of low and medium Results of the experiments showed that the soil mc had a significant effect on operating depth of disk coulter horizontal resistance index HCI and vertical cone index VCI With an increase in mc the operating depth of the disk coulter increased whereas the HCI and VCI were decreased Also the results showed that the penetrating depth of the disk coulter was sensitive to changes in surface soil strength The measured HCI with horizontal sensor was independent of soil failure induced by the disk coulter in front of the prismatic tips This was due to the fact that the disk coulter of the vertical sensor was a very narrow tine At both mcs the relations between the operating depth of the disk coulter and the VCI were significant Also the relationships between the HCI and VCI at both depths and at both mcs were significant Therefore the developed integrated sensor could be used to map the mechanical resistance of the topsoil and subsoil at the same time Keyword Integrated sensor Cone penetrometer Horizontal resistance index Cone index

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طراحي ساخت و ارزيابي حسگر تركيبي مقاومت مكانيكي خاك به صورت بلادرنگ

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