We perform combined resistivity and compressibility studies of two-dimensional hole and electron systems which show the apparent metal-insulator transition--a crossover in the sign of deltaR/deltaT with changing density. No thermodynamic anomalies have been detected in the crossover region. Instead, despite a tenfold difference in r(s), the compressibility of both electrons and holes is well de...

helicopter-borne frequency-domain electromagnetic (hem) surveys are used extensively for mineral and groundwater exploration and a number of environmental investigations. to have a meaningful interpretation of the measured multi- frequency hem data, in addition to the resistivity maps which are provided in each frequency or for some particular depth levels, it is a necessity to have a suit...

For the analysis of soil resistivity results and measurement, engineers have guidelines instructions from various international standards at their disposal. The circumstances under which mathematical expressions in these were obtained are not always clear. One such case is described this article refers to IEEE Standard 81-1983, an expression for apparent resistivity, a theoretical model predict...

A straightforward inversion scheme (SIS) has been developed to interpret vertical electrical sounding data. This scheme does not require quasi-linearization of the inverse resistivity problem and thereby dispenses with the iterative process and the necessity of guessing the number of layers and their resistivities and thicknesses. The entire solution domain is divided into uniform thickness lay...

magnetotelluric (mt) method is a passive electromagnetic technique that uses the natural, time varying electric and magnetic field components measured at right angles at the surface of the earth to make inferences about the earth’s electrical structure which, in turn, can be related to the geology tectonics and subsurface conditions. reflection and refraction of electromagnetic (em) signals at ...