Static image principle for anisotropic‐conducting half‐space problems: PEC and PMC boundaries

Geophysics ◽  
1993 ◽  
Vol 58 (12) ◽  
pp. 1861-1864 ◽  
Author(s):  
Ismo V. Lindell ◽  
Murat E. Ermutlu ◽  
Keijo I. Nikoskinen ◽  
Esko H. Eloranta
Keyword(s):  
Electrical Conductivity ◽  
Half Space ◽  
Electric Fields ◽  
Geophysical Methods ◽  
Image Method ◽  
Static Case ◽  
Electric Conductor ◽  
Perfect Magnetic Conductor ◽  
Anisotropic Conducting

The image principle for an isotropic half‐space bounded by perfect electric conductor (PEC) or perfect magnetic conductor (PMC) plane is presented in most elementary textbooks on electromagnetics. It is perhaps not so well known that this principle can also be generalized to anisotropic media in the static case, because it is not covered in leading monographs of geoelectromagnetics (Wait, 1982; Negi and Saraf, 1989; Eskola, 1992). The anisotropic image method can be applied to geologic media that exhibit anisotropic electrical conductivity caused by the fractures and fissures in the rock. Such structures are important in the sites for disposal of nuclear waste. The characterization of these structures by electrical geophysical methods is very essential because they form the main paths for groundwater flow. The air‐ground boundary can be treated as a PMC plane representing the nonconducting medium. Otherwise the medium is assumed to be linear (ohmic) and homogeneous in terms of electrical conductivity. The image method presented is also relevant to problems arising in the traditional ore prospecting where a conducting ore body buried in an electrically anisotropic host rock generates secondary electric fields (Asten, 1974; Eloranta, 1988).

Landfill investigation using geophysical methods for an improved characterization of the landfill geometry and for assessing microbiological activity

2020 ◽  
Author(s):  
Lukas Aigner ◽  
Jakob Gallistl ◽  
Matthias Steiner ◽  
Christian Brandstätter ◽  
Johann Fellner ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Greenhouse Gas ◽  
Spatial Scales ◽  
Landfill Gas ◽  
Geophysical Methods ◽  
Gas Production ◽  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Transient Electromagnetic

<p>The release of landfill gas is responsible for approximately 3 % of the global greenhouse gas emissions. Especially a high content of organic matter in municipal solid waste (MSW) in wet areas may enhance the microbial activity and the production of landfill gas and leachate as metabolic products. Accordingly, the delineation of saturated zones and biogeochemically active and inactive areas is critical for designing adequate stabilization systems to limit the environmental impact of landfills on greenhouse gas production. Therefore, landfill investigations with high spatial resolution are critical for environmental protection. Geophysical methods are a cost-efficient possibility to obtain almost continuous information about subsurface properties at various spatial scales, which can help to identify biogeochemical active zones. Within this case study we investigate the applicability of three geophysical methods, namely (i) the electrical resistivity tomography (ERT), (ii) the induced polarization (IP) method and (iii) the transient electromagnetic (TEM) method to characterize the landfill geometry and to discriminate between biogeochemically active and inactive areas. The investigated landfill is located close to Vienna (Austria) and consists of a mixture of MSW, construction and demolition waste (CDW) and excavated soil. We conducted ERT and IP measurements along 17 profiles distributed over the area of the landfill to provide high resolution images of the subsurface down to 8 m depth. Additionally, we used transient electromagnetic measurements along selected profiles to provide information on deeper structures of the landfill as well as to evaluate the electrical conductivity obtained with ERT. Our results show that the electrical conductivity obtained by both ERT and TEM is mainly sensitive to the increase in the fluid conductivity associated to leachate production and migration. Additionally, a decrease in electrical conductivity is associated to CDW and dry MSW and can help to distinguish between different waste types. However, images of the polarization effect obtained with the IP method, expressed in terms of the phase of the complex conductivity, revealed an improved contrast to characterize variations in the architecture and biogeochemical activity of the landfill. Hence, our study demonstrates that the geophysical methods we applied are well-suited for landfill investigations permitting an improved characterization of landfill geometry and variation in waste composition. In particular, the IP method can delineate between biogeochemically active and inactive zones.</p>

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

CHARACTERIZATION OF SPATIAL VARIABILITY OF SOIL ELECTRICAL CONDUCTIVITY AND CONE INDEX USING COULTER AND PENETROMETER-TYPE SENSORS

Soil Science ◽  
2006 ◽  
Vol 171 (8) ◽  
pp. 627-637 ◽  
Author(s):  
Jay David Jabro ◽  
Robert G. Evans ◽  
Yunseup Kim ◽  
William B. Stevens ◽  
William M. Iversen
Keyword(s):  
Electrical Conductivity ◽  
Spatial Variability ◽  
Soil Electrical Conductivity ◽  
Cone Index

scholarly journals Refractive index sensing and surface-enhanced Raman spectroscopy using silver–gold layered bimetallic plasmonic crystals

2017 ◽  
Vol 8 ◽  
pp. 2492-2503 ◽  
Author(s):  
Somi Kang ◽  
Sean E Lehman ◽  
Matthew V Schulmerich ◽  
An-Phong Le ◽  
Tae-woo Lee ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Refractive Index ◽  
Electric Fields ◽  
Surface Enhanced Raman Spectroscopy ◽  
Plasmonic Crystals ◽  
Metal Thickness ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Difference Time

Herein we describe the fabrication and characterization of Ag and Au bimetallic plasmonic crystals as a system that exhibits improved capabilities for quantitative, bulk refractive index (RI) sensing and surface-enhanced Raman spectroscopy (SERS) as compared to monometallic plasmonic crystals of similar form. The sensing optics, which are bimetallic plasmonic crystals consisting of sequential nanoscale layers of Ag coated by Au, are chemically stable and useful for quantitative, multispectral, refractive index and spectroscopic chemical sensing. Compared to previously reported homometallic devices, the results presented herein illustrate improvements in performance that stem from the distinctive plasmonic features and strong localized electric fields produced by the Ag and Au layers, which are optimized in terms of metal thickness and geometric features. Finite-difference time-domain (FDTD) simulations theoretically verify the nature of the multimode plasmonic resonances generated by the devices and allow for a better understanding of the enhancements in multispectral refractive index and SERS-based sensing. Taken together, these results demonstrate a robust and potentially useful new platform for chemical/spectroscopic sensing.

Preparation and Characterization of Porous Si-Coated SiC Fiber Media

2004 ◽  
Vol 449-452 ◽  
pp. 233-236 ◽  
Author(s):  
Jun Suh Yu ◽  
B.S. Lee ◽  
Sung Churl Choi ◽  
Ji Hun Oh ◽  
Jae Chun Lee
Keyword(s):  
Electrical Conductivity ◽  
Silicon Content ◽  
Porous Si ◽  
Electrically Conductive ◽  
Electrode Distance ◽  
Sic Fiber ◽  
Effective Electrical Conductivity ◽  
The One ◽  
Fiber Preforms

Electrically conductive porous Si/SiC fiber media were prepared by infiltration of liquid silicon into porous carbon fiber preforms. The series rule of mixture for the effective electrical conductivity was applied to the disc shaped samples to estimate their silicon content, effective electrical conductivity and porosity. The electrical conductivity was estimated by assuming the disc sample as a plate of equivalent geometry, i.e., same thickness, electrode distance and volume. As the volumetric content of silicon in a sample increases from 0.026% to 0.97%, the estimated electrical conductivity increases from 0.17 S/cm to 2.09 S/cm. The porosity of the samples measured by Archimedes principle was in the range of 75~83% and 1~4% less than the one estimated by the series rule of mixture for the effective electrical conductivity.

scholarly journals MICROWAVE CHARACTERIZATION OF ELECTRICAL CONDUCTIVITY OF COMPOSITE CONDUCTORS BY HALF-WAVELENGTH COPLANAR RESONATOR

2016 ◽  
Vol 60 ◽  
pp. 73-80 ◽  
Author(s):  
Bilal Benarabi ◽  
Faouzi Kahlouche ◽  
Bernard Bayard ◽  
Anthony Chavanne ◽  
Jeremy Sautel
Keyword(s):  
Electrical Conductivity ◽  
Microwave Characterization ◽  
Half Wavelength ◽  
Composite Conductors
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