International Journal of Environmental Chemistry
IMAGING OF A FAR SURFACE OBJECT WITH HORIZONTAL LOOP ELECTROMAGNETIC INSTRUMENT
Abstract
An electromagnetic imaging instrument with variable voltage and frequency was designed and constructed to image a far surface metallic object. The methodology involved the transmitted voltage of 250V to the transmitter core with frequency of 300Hz. The liquid crystal display (LCD) module was used to display the computed voltage values after being processed by the microcontroller unit. The constructed instrument took measurement at horizontal profiling to 30m along the surface and vertical profiling to 310cm across the surface. The horizontal profiling and vertical measurements were made on 0cm,70cm,120cm,150cm,180cm,210cm,240cm, 310cm across the surface and 0m, 4m, 7m, 12m, 17m, 20m, 25m, 30m, along the surface, where cast iron metal pipes are placed on the flat surface. The 130cm iron pipe placed between 90cm – 220cm while the 72cm iron pipe was placed between 119cm -191cm perpendicular to the surface. The results obtained show that as the distance along and across the surface increases, the receiver voltage decreases when 250V are transmitted. Various 2 –D column plots were made from measured receiver voltages for flat surface measurement. These 2-D column plots of the data indicate the locations of the test iron pipes and other metallic objects on the flat surface measurements. Keywords: Imaging, surface, object, horizontal loop ,electromagnetic instrument.References (8)
- Becker,A.(1979). Airborne electromagnetic methods. In Geophysics and geochemistry in the search for metallic ores. Report 31, 33-44.
- Fraser,D.C.(1996). Resistivity mapping with an airborne multi coil electromagnetic system. Geophysics 43, 144-172.
- Frischknecht, F.C.(1967). Fields about an oscillating magnetic dipole over a two layer earth and application to ground and airborne electromagnetic survey. Colorado school of mines quarterly 62, 32-39.
- Kawak, K.S.(1996). Priorities in designing Earth observation. Geophysics 88, 420-428.
- Lautebur,P.C.(2009). Electromagnetic imaging method for detecting metallic objects in the subsurface: Fixed frequency EM profiling. Geophysics 223, 109-120.
- Lowrie, W.(1999). The effect of conducting over burden on electromagnetic prospecting measurement. Geophysics 30, 632-640.
- Mook,G. Michael, F and Simonin,J.(2008). Electromagnetic imaging using probe arrays. 17th world conference on nondestructive testing, 25-28th October,2008, Honghai, China.
- Owolabi,J.A.(2014). Design, Construction and Application of variable frequency and voltage electromagnetic imaging instrument for detecting buried pipes. Ph.D Thesis.