Induced polarization response within a spheroidal particle from an incident electromagnetic wave

2020 ◽  
Author(s):  
Michael E. Thomas ◽  
Richard I. Joseph
Keyword(s):  
Electromagnetic Wave ◽  
Induced Polarization ◽  
Spheroidal Particle ◽  
Incident Electromagnetic Wave ◽  
Polarization Response

CLASSICAL ELECTROMAGNETICALLY-INDUCED TRANSPARENCY-LIKE SWITCHING CONTROLLED BY POLARIZATION IN METAMATERIALS

2013 ◽  
Vol 22 (01) ◽  
pp. 1350004 ◽  
Author(s):  
XING RI JIN ◽  
JINWOO PARK ◽  
HAIYU ZHENG ◽  
YOUNGPAK LEE ◽  
JOO YULL RHEE ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetically Induced Transparency ◽  
Microwave Frequency ◽  
Dielectric Substrate ◽  
Frequency Region ◽  
Ring Resonators ◽  
Split Ring ◽  
Split Ring Resonators ◽  
Incident Electromagnetic Wave ◽  
Induced Transparency

The classical electromagnetically-induced transparency (EIT)-like switching in metamaterials was experimentally demonstrated in the microwave-frequency region. The metameterial unit cell consists of two identical split-ring resonators, which are arranged on both sides of a dielectric substrate with 90°-rotation asymmetry. In our scheme, the classical EIT-like switching can be achieved by changing the polarization of the incident electromagnetic wave.

Determining frequency dependence of carbon turnover in peat using spectral induced polarization

2021 ◽  
Author(s):  
Timea Katona ◽  
Benjamin Gilfedder ◽  
Sven Frei ◽  
Lukas Aigner ◽  
Matthias Bücker ◽  
...  
Keyword(s):  
Frequency Dependence ◽  
Iron Oxides ◽  
Induced Polarization ◽  
Electrode Spacing ◽  
Electrode Polarization ◽  
Biogeochemical Processes ◽  
Carbon Turnover ◽  
Spectral Induced Polarization ◽  
Polarization Response ◽  
Imaging Results

<p>Our study discusses imaging results from a spectral induced polarization (SIP) survey to identify concurring processes (such as aerobic respiration, denitrification, or sulfate- and iron reduction) in a biogeochemically active peat in a wetland located in the Lehstenbach catchment in Southeastern Germany. Terrestrial wetland ecosystems such as peatlands are a critical element in the global carbon cycle. Due to their role as natural carbon sinks and ecological importance for an array of flora and fauna, there is a growing demand to conserve and restore degraded peatlands. Biogeochemical processes occur with non-uniform reaction rates within the peat, making the environment sensitive to physical disturbances. To investigate biogeochemical processes in-situ, it is important to avoid disturbing the redox-sensitive conditions in the subsurface by bringing oxygen into anoxic areas.  Our previous study demonstrated that the induced polarization (IP) was able to identify biogeochemically active and inactive areas of the peat. The IP response was sensitive to the presence of carbon turnover and P release in the absence of iron sulfide. These highly polarizable areas have high iron concentrations, but most likely in an oxidized form. As most iron oxides are poor conductors, the strong polarization response is unlikely related to an electrode polarization process.</p><p>Here we also analyzed the frequency dependence of the SIP data to investigate whether iron oxides and carbon-iron complexes, two possible mechanisms for the high polarization response, can be distinguished. SIP imaging data sets covered the frequency range between 0.06 and 225 Hz and were collected with varying electrode spacing (20 and 50 cm) at different locations within the Waldstein catchment characterized by different properties, e.g., saturated and non-saturated soils. Our imaging results reveal variations of the IP effect within the peat layer, indicating substantial heterogeneities in the peat composition and biogeochemical activity. The frequency dependence allowed us to resolve a sharper contrast between the different features of the peat. Geochemical analyses on a freeze core and pore water samples are used to validate our results and find correlations between the Cole-Cole parameters of the SIP response and the geochemical parameters.</p>

Time-domain-induced polarization: Full-decay forward modeling and 1D laterally constrained inversion of Cole-Cole parameters

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. E213-E225 ◽  
Author(s):  
Gianluca Fiandaca ◽  
Esben Auken ◽  
Anders Vest Christiansen ◽  
Aurélie Gazoty
Keyword(s):  
Time Domain ◽  
Mineral Exploration ◽  
Induced Polarization ◽  
Significant Loss ◽  
Step Response ◽  
Model Parameters ◽  
Full Time ◽  
Inversion Algorithm ◽  
Modeling Tools ◽  
Polarization Response

Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use of time-domain-induced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function, to reconstruct the distribution of the Cole-Cole parameters of the earth. The accurate modeling of the transmitter waveform had a strong influence on the forward response, and we showed that the difference between a solution using a step response and a solution using the accurate modeling often is above 100%. Furthermore, the presence of low-pass filters in time-domain-induced polarization instruments affects the early times of the acquired decays (typically up to 100 ms) and has to be modeled in the forward response to avoid significant loss of resolution. The developed forward code has been implemented in a 1D laterally constrained inversion algorithm that extracts the spectral content of the induced polarization phenomenon in terms of the Cole-Cole parameters. Synthetic examples and field examples from Denmark showed a significant improvement in the resolution of the parameters that control the induced polarization response when compared to traditional integral chargeability inversion. The quality of the inversion results has been assessed by a complete uncertainty analysis of the model parameters; furthermore, borehole information confirm the outcomes of the field interpretations. With this new accurate code in situ time-domain-induced polarization measurements give access to new applications in environmental and hydrogeophysical investigations, e.g., accurate landfill delineation or on the relation between Cole-Cole and hydraulic parameters.

scholarly journals Induced polarization response of porous media with metallic particles — Part 7: Detection and quantification of buried slag heaps

Geophysics ◽  
2018 ◽  
Vol 83 (5) ◽  
pp. E277-E291 ◽  
Author(s):  
Youzheng Qi ◽  
Abdellahi Soueid Ahmed ◽  
André Revil ◽  
Ahmad Ghorbani ◽  
Feras Abdulsamad ◽  
...  
Keyword(s):  
Metal Content ◽  
Induced Polarization ◽  
Ore Deposits ◽  
Magnetic Method ◽  
Complex Conductivity ◽  
Metallic Particles ◽  
Polarization Response ◽  
Slag Heap ◽  
Detection And Quantification ◽  
Metallurgical Activities

With the progress of metallurgical activities, more and more dumped slag heaps emerge as valuable deposits to feed the growing need for metal resources. Detecting, quantifying, and reextracting metals from these slags may complement the prospection of new ore deposits. However, the spatial delineation of the slag heap cannot easily be obtained from the resistivity distribution alone (determined either with galvanometric or with induction-based methods). Although the magnetic method can detect slag heaps, it fails to make an estimation of the quantity of metal present in the slag. Alternatively, the induced polarization (IP) method can be used to fulfill this goal. The complex conductivity responses of slag samples from a slag heap in France are obtained in the laboratory. These data are used to assess the grade of the slag, which is close to 8%. Then, a least-squares 3D IP inversion is used to get the subsurface chargeability distribution delimiting the slag heap in the ground. From the linear relationship determined between the chargeability and the volumetric metal content or the volumetric slag content, the metallic volume of the slag heaps can be directly determined. This approach is used at the site of Saint-Vincent sur L'Isle, Dordogne (France), where it allows characterizing the shape of a slag heap and quantifying the total cumulative metal content of the investigated area.

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