scholarly journals On the laboratory calibration of dielectric permittivity models for agricultural soils: Effect of systematic porosity variation

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Xicai Pan ◽  
Yudi Han ◽  
Kwok Pan Chun ◽  
Jiabao Zhang ◽  
Donghao Ma ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Agricultural Soils ◽  
Porosity Variation ◽  
Laboratory Calibration

Time domain reflectrometry measurements of water content in coarse waste rock

2003 ◽  
Vol 40 (1) ◽  
pp. 137-148 ◽  
Author(s):  
Craig Nichol ◽  
Leslie Smith ◽  
Roger Beckie
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
Ambient Temperature ◽  
Water Content ◽  
Travel Time ◽  
Pore Water ◽  
Time Domain ◽  
Waste Rock ◽  
High Electrical Conductivity ◽  
Laboratory Calibration

Methods are presented to calibrate and implement a time domain reflectrometry (TDR) system to estimate the water content of coarse mine waste rock containing high solute concentrations in the pore water. High electrical conductivity of the pore water reduces the quality of TDR waveforms through the loss of signal amplitude. Zegelin-type probes with a resistive coating on the center conductor were used to obtain higher signal-to-noise waveforms. These probes must be calibrated prior to use. The TDR pulse travel-time measured in soils containing pore water with high solute concentrations increases systematically with solute concentration. Empirical calibrations are derived for waste rock with low and high electrical conductivity pore water. An ambient temperature correction is derived from observed diurnal fluctuations in the measured travel time to determine whether or not a detailed laboratory calibration for temperature effects is required. The variation of apparent dielectric permittivity with temperature is positively correlated with temperature at low water content and negatively correlated at high water content. This trend indicates the influence of water bound to mineral surfaces on the variation of apparent dielectric permittivity with temperature. Examination of our field data indicates that the effect of dissolved ions on the TDR calibration was great enough to justify a calibration that accounts for pore-water composition. The effect of ambient temperature was found to be small enough that an intensive laboratory calibration was not required.Key words: time domain reflectrometry, water content, mining.

Dielectric permittivity in the x-ray region

1978 ◽  
Vol 126 (11) ◽  
pp. 479-513 ◽  
Author(s):  
A.V. Kolpakov ◽  
V.A. Bushuev ◽  
R.N. Kuz'min
Keyword(s):  
Dielectric Permittivity ◽  
X Ray

Examination of NOxand CO2production in agricultural soils

2007 ◽  
Vol 35 (2) ◽  
pp. 689-692 ◽  
Author(s):  
Krisztina Kristóf ◽  
Györgyi Kampfl ◽  
György Heltai ◽  
Erika Nótás ◽  
Abdousalam Algaidi
Keyword(s):  
Agricultural Soils

The Determination of the Magnetoelectric Coupling Coefficient in Ferroelectric–Ferromagnetic Composite Based on PZT–Ferrite

2013 ◽  
Vol 58 (4) ◽  
pp. 1401-1403 ◽  
Author(s):  
J.A. Bartkowska ◽  
R. Zachariasz ◽  
D. Bochenek ◽  
J. Ilczuk
Keyword(s):  
Dielectric Permittivity ◽  
Coupling Coefficient ◽  
Mean Field ◽  
Field Approximation ◽  
Theoretical Description ◽  
Magnetoelectric Coupling ◽  
Mean Field Approximation ◽  
Dielectric Measurements ◽  
Temperature Dependences ◽  
Multiferroic Composite

Abstract In the present work, the magnetoelectric coupling coefficient, from the temperature dependences of the dielectric permittivity for the multiferroic composite was determined. The research material was ferroelectric-ferromagnetic composite on the based PZT and ferrite. We investigated the temperature dependences of the dielectric permittivity (") for the different frequency of measurement’s field. From the dielectric measurements we determined the temperature of phase transition from ferroelectric to paraelectric phase. For the theoretical description of the temperature dependence of the dielectric constant, the Hamiltonian of Alcantara, Gehring and Janssen was used. To investigate the dielectric properties of the multiferroic composite this Hamiltonian was expressed under the mean-field approximation. Based on dielectric measurements and theoretical considerations, the values of the magnetoelectric coupling coefficient were specified.

Compressive response of some agricultural soils influenced by the mineralogy and moisture

2013 ◽  
Vol 27 (3) ◽  
pp. 239-246 ◽  
Author(s):  
A.E. Ajayi ◽  
M.S. Dias Junior ◽  
N. Curi ◽  
I. Oladipo
Keyword(s):  
Agricultural Soils ◽  
Tropical Soils ◽  
Homogeneity Test ◽  
Confined Compression ◽  
Moisture Retention ◽  
Soil Mineralogy ◽  
Undisturbed Soil ◽  
Statistical Homogeneity ◽  
Compressive Response ◽  
Fine Clay

Abstract This study aimed to investigate the mineralogy, moisture retention, and the compressive response of two agricultural soils from South West Nigeria. Undisturbed soil cores at the A and B horizons were collected and used in chemical and hydrophysical characterization and confined compression test. X-ray diffractograms of oriented fine clay fractions were also obtained. Our results indicate the prevalence of kaolinite minerals relating to the weathering process in these tropical soils. Moisture retention by the core samples was typically low with pre-compression stress values ranging from50 to 300 kPa at both sites. Analyses of the shape of the compression curves highlight the influence of soil moisture in shifts from the bi-linear to S-shaped models. Statistical homogeneity test of the load bearing capacity parameters showed that the soil mineralogy influences the response to loading by these soils. These observations provide a physical basis for the previous classification series of the soils in the studied area. We showed that the internal strength attributes of the soil could be inferred from the mineralogical properties and stress history. This could assist in decisions on sustainable mechanization in a datapoor environment.

Heavy Metal Content of Agricultural Soils at Tumu, Akko Local Government Area of Gombe State, Nigeria

2019 ◽  
Vol 9 (2) ◽  
pp. p8693
Author(s):  
Ogidi A. Ogidi ◽  
Danja B. A. ◽  
Sanusi K. A. ◽  
Nathaniel Sunday Samuel ◽  
Abdurrahman Abubakar ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Local Government ◽  
Metal Content ◽  
Agricultural Soils ◽  
Local Government Area ◽  
Heavy Metal Content
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