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Technology of Passive Magnetic Resonance (PMRSE Technology) |
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Contents
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PMRSE
(Passive Magnetic Resonance Subsurface Exploration) is an innovative
technology of non-invasive subsurface investigations. It is based on a
non-intrusive reception of natural electromagnetic fields of the Earth
and extraction of a useful signal from electromagnetic noise using the
method of stochastic resonance. |
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The
object
of investigations using PMRSE technology are any subsurface
irregularities, both substantive and structural, with their unique
resonance frequencies of electromagnetic radiation. |
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PMRSE measuring complex
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The measuring system applied for field observations is a hybrid biotechnical complex including electronic equipment and an operator of the complex who is connected to the equipment by means of special sensors. The principle of work of the PMRSE measuring system consists in achieving the state of stochastic resonance, which in turn is achieved by summation of the additive noise (noise of nervous and muscular tissues of the operator, noise generated by the equipment and the natural electromagnetic radiation of the Earth received by a directional antenna) and a reference signal of the preset frequency generated by the electronic equipment. The useful signal is detected and recorded based on the threshold effect and the adaptive reaction of nervous and muscular tissues of the operator. The relative value of the signal at a resonance frequency is estimated indirectly in accordance with psychophysical laws linking the amount of sensation with the value of the actual stimulus. The design of the measuring system makes it possible to adjust the sensory threshold of nervous and muscular tissues of the operator by an extra stimulating action. The value of this action can be smoothly modified and measured in real physical units.
The electronic unit of the measuring complex is fitted with reference generators of electromagnetic waves, processor, built-in memory and GPS, directional small electric antenna for receiving signals of circular polarization, neurosensors, connector for a standard computer port, laptop, battery for 7-8 hours of autonomous work, and other servicing and measuring devices. The electronic unit of the measuring complex is quite compact and convenient to work afoot, when needed. The electronic equipment of the measuring complex is used to run the remote measurements and record signals at a resonance frequency.
When searching for a specific substance, its resonance frequency used as a reference during measurements is determined beforehand whereas the physical value of the stimulating action needed to achieve the sensory threshold is calibrated at artificial models with different substance contents. This allows to carry out subsurface explorations of different kinds of minerals, chemical elements and compounds and present the results in real concentrations of the substance of concern. Calibration tests are already performed for a wide range of substances and the experimental relationships between the signal intensity at a preset frequency and the substance content are determined.
Bedding depth of the objects of concern is determined using resonance wavelengths of radio frequency and a special calculation method. In calculations the resonance properties of antennas used and peculiarities of propagation of circular polarized electromagnetic waves, which form electromagnetic noise of the Earth, in the rock mass are taken into account.
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At present all the
field explorations
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The technology can be used in two exploration modes: mapping and sounding. While mapping allows exploring subsurface objects in plan, soundings allow exploring subsurface objects in a vertical perspective.
The PMRSE mapping is performed by way of intersecting the objects (territories) under investigation along some profiles or routes. The distance between profiles of investigations is determined based on the level of details required and accessibility of the territory. The frequency of measurements on the profile has practically no limits except that it depends on the speed of movement when using vehicles and doing measurements in motion. When moving along the profile one electronic unit can make records of one parameter at a time. Usually this is a substance content. The technology also allows to directly trace contacts of rocks, tectonic fractures, karst caverns, etc.
When doing mapping the work productivity depends on the exploration details required and vehicle used. If exploring afoot, in 1 working day one operator can cover the grid of profiles total 6-8 km long taking readings for one parameter. Using a car such measurements can be performed on the grid of profiles total 100-150 km long.
The results of mapping allow to plot areal maps of mineral deposits, plumes of chemical contamination of underground water and soil in form of projections on the daylight surface or slice-maps at a set depth.
Example of mapping:
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Examples of soundings:
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The PMRSE depth sounding, similar to a standard well log, allows to study a geologic section in a vertical or slanted projection and does not need well boring. Depending on the given tasks the soundings are performed in points selected arbitrarily or based on a net. Signal recording is performed according to a preset step of measurements from the ground surface down to a required depth or within a set depth interval. Explorations can be performed at the depth from 0 to 15,000 m. The resolution and the minimum step of measurements during soundings depend on the resonance wavelength of the objects of concern as well as resonance properties of the antenna and vary from 1-2 cm up to several decimeters.
During soundings all the measurements are discrete but when the measurements are performed with a certain resonance wavelength ratio taken into account the technology provides a continuous description of the geologic section in the point of sounding.
In each selected point, soundings are usually performed for a number of parameters. To get a picture of the geologic section the obligatory parameters for measurements during depth soundings for any project are density and moisture of rocks in their natural occurrence as well as a content of two or three rock-forming minerals. Additionally, the measurements of content of the substances of concern are carried out to the whole exploration depth or in a set depth interval. In exploration projects the substances of concern can be any kinds of minerals and in environmental projects these can be any chemical compounds of a technogenic origin.
When doing vertical soundings the work productivity in a separate point depends on the step of measurements and the number of parameters recorded. When measuring one parameter with the step of 10 cm one operator in 1 working day can perform sounding to the depth of 500-1,000 m. When measuring one parameter with the step of 1 m one operator in 1 working day can perform up to 10,000 running meters of soundings.
The results of soundings allow to construct lithologic columns, geologic sections, structural maps, maps showing bedding depths of underground water and other geologic models including three-dimensional ones.
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