scholarly journals The Effect of Bulk Density on Emission Behavior of Soil at Microwave Frequencies

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
V. K. Gupta ◽  
R. A. Jangid
Keyword(s):  
Dielectric Constant ◽  
Bulk Density ◽  
Soil Surface ◽  
Microwave Remote Sensing ◽  
Microwave Frequency ◽  
Soil Samples ◽  
Microwave Emission ◽  
Complex Dielectric Constant ◽  
Semiempirical Model ◽  
Surface Boundary

Dielectric constant and dielectric loss (ε′ and ε″) of different soil samples with bulk densities varying from 1.3 to 2.0 gm/cm3 are determined at a single microwave frequency 9.78 GHz and at temperature 37.0°C. Different bulk densities of same soil are achieved by filling the wave guide cell with an equal volume but a different mass of soil. Further, ε′ and ε″ of these soil samples are also estimated by semiempirical model and compared with the experimental results. The values of ε′ and ε″ increase as bulk density of the soil increases. In view of microwave remote sensing, the Fresnel reflectivity of soil is computed from the knowledge of the complex dielectric constant and the surface boundary condition. Using Kirchhoff’s reciprocity theorem the microwave emissivity is estimated from Fresnel reflectivity of the surface. It is observed that the microwave emission from the soil surface inhibits as bulk density of soil increases. Further, the roughness of soil surface has been taken into consideration in the emissivity computation and observed that the emissivity increases with increasing roughness of the soil surface.

Low-frequency dielectric dispersion and microwave dielectric properties of dry and water-saturated limestones of Jodhpur region

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. G269-G277 ◽  
Author(s):  
R. J. Sengwa ◽  
A. Soni
Keyword(s):  
Dielectric Constant ◽  
Chemical Composition ◽  
Bulk Density ◽  
Low Frequency ◽  
Dielectric Dispersion ◽  
Complex Dielectric Constant ◽  
Frequency Limit ◽  
Microwave Dielectric ◽  
Limestone Sample ◽  
Water Saturated

We investigated the complex dielectric constant of 17 different grades of dry and water-saturated limestone samples from the Jodhpur region in the frequency range of [Formula: see text] to [Formula: see text] and also at [Formula: see text] at room temperature. The Cole-Cole dielectric dispersion model was used to compute the values of low-frequency-limit dielectric constant, high-frequency-limit dielectric constant, dielectric strength, and principal value of the relaxation time for each dry limestone sample. The chemical composition, sample bulk density, and porosity of each sample studied were determined to learn which of these factors govern their dielectric parameters. Analysis of the low-frequency dielectric constant confirms that chemical composition and bulk density are the ma-jor factors governing the dielectric constant values; but for water-saturated samples, the frequency-dependent dielectric constant values are also sensitive to porosity and grain size. The ac conductivity of all of the dry samples increases with the increase in frequency from [Formula: see text] to [Formula: see text], but water-saturated samples have comparatively high conductivity; some samples have values independent of the frequency. The microwave dielectric constant of dry samples depends mainly on the amount of the constituents of the oxide, their chemical composition, and sample bulk density. The contribution of the measured dielectric-constant values of each oxide present in the sample is identified by using their density-reduced values of the dielectric constant. The porosity-dependent mixing equations for solid and fluid components of the system were also found suitable for determining the dielectric constant of water-saturated limestone samples at microwave frequency.

Experimental Study of C Band Passive Microwave Remote Sensing of Soil Moisture

2013 ◽  
Vol 477-478 ◽  
pp. 624-627
Author(s):  
Xiao Liu Gao ◽  
Hui Hui Zhang
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Emission Rate ◽  
Soil Surface ◽  
Microwave Remote Sensing ◽  
Passive Microwave ◽  
Microwave Emission ◽  
Passive Microwave Remote Sensing ◽  
Soil Surface Roughness ◽  
Relationship Of

Passive microwave remote sensing is one of the most effective methods for inversing soil moisture. Under the condition of laboratory, firstly, C band microwave radiation was used to achieve the trial of ground-based remote sensing soil moisture, and then regression analysis was carried out according to the data measured, finally, got the C band experience regression model of soil moisture inversion. The results showed that: in the level-off state of soil surface, soil humidity and soil microwave emission rate is linear negative correlation, in the other words, soil microwave emission rate decreased while the soil moisture increased. Besides, with the increasing of soil surface roughness, both the value of microwave polarization index (MPDI) and microwave emission rate polarization difference Δe have the same trend of quick drop, stabilization and slow raise, and it presented the relationship of quadratic curve with the change of roughness.

Novel Evaluation Method of the Complex Dielectric Constant of High-Permittivity Material at Microwave Frequency

2004 ◽  
Vol 43 (9B) ◽  
pp. 6755-6758 ◽  
Author(s):  
Kikuo Wakino ◽  
Sousuke Kumagai ◽  
Takeshi Shiraishi ◽  
Toshihide Kitazawa ◽  
Takashi Fujii ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Evaluation Method ◽  
Microwave Frequency ◽  
Complex Dielectric Constant ◽  
High Permittivity

scholarly journals Mineral Soil Texture–Land Cover Dependency on Microwave Dielectric Models in an Arid Environment

Land ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 39
Author(s):  
Saeid Gharechelou ◽  
Ryutaro Tateishi ◽  
Brian A. Johnson
Keyword(s):  
Dielectric Constant ◽  
Land Cover ◽  
Soil Texture ◽  
Mineral Soil ◽  
Relative Dielectric Constant ◽  
Microwave Remote Sensing ◽  
Soil Samples ◽  
Northern Iran ◽  
Moisture Condition ◽  
Field Samples

In this study, we measured and characterized the relative dielectric constant of mineral soils over the 0.3–3.0 frequency range, and compared our measurements with values of three dielectric constant simulation models (the Wang, Dobson, and Mironov models). The interrelationship between land cover and soil texture with respect to the dielectric constant was also investigated. Topsoil samples (0–10 cm) were collected from homogenous areas based on a land unit map of the study site, located in the Gamsar Plain in northern Iran. The field soil samples were then analyzed in the laboratory using a dielectric probe toolkit to measure the soil dielectric constant. In addition, we analyzed the behaviors of the dielectric constant of the soil samples under a variety of moisture content and soil fraction conditions (after oven-drying the field samples), with the goal of better understanding how these factors affect microwave remote sensing backscattering characteristics. Our laboratory dielectric constant measurements of the real part (ε′) of the frequency dependence between the factors showed the best agreement with the results obtained by the Mironov, Dobson, and Wang models, respectively, but our laboratory measurements of the imaginary part (ε″) did not respond well and showed a higher value in low frequency because of salinity impacts. All data were analyzed by integrating them with other geophysical data in GIS, such as land cover and soil textures. The result of the dielectric constant properties analysis showed that land cover influences the moisture condition, even within the same soil texture type.

scholarly journals Analysis and Modeling of the Complex Dielectric Constant of Bound Water with Application in Soil Microwave Remote Sensing

2020 ◽  
Vol 12 (21) ◽  
pp. 3544
Author(s):  
Xiao Jin ◽  
Wen Yang ◽  
Xiaoqing Gao ◽  
Zhenchao Li
Keyword(s):  
Dielectric Constant ◽  
Soil Water ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Layer Structure ◽  
Bound Water ◽  
Microwave Remote Sensing ◽  
Dielectric Constants ◽  
Complex Dielectric Constant ◽  
Double Layer Structure

Complex dielectric constant (CDC) of bound water determines the accuracy of the complex dielectric constant of wet soil. According to electrical double-layer structure and dielectric properties, the bound water on clay particle surface is divided into strongly bound water and weakly bound water. Based on this classification, models for the complex dielectric constants of bound water and soil are established taking into consideration factors such as temperature, moisture, texture, and microwave frequency. The results show that the fundamental reason why the complex dielectric constant of bound water is between that of ice and free water is the adsorption force which forms the electrical double-layer structure on the surface of clay particles. Low-concentration cationic solution could exist in free soil water and was found as the reason for the higher salinity and conductivity of free soil water, as compared to the measured soil solution. Results of soil CDC model are in good agreement with measured data across a wide range of microwave frequencies and soil temperature, moisture, and texture. The absolute root mean square error analysis also shows that the soil CDC model in this paper compared to the other models is more accurate.

COMPLEX DIELECTRIC CONSTANT OF CIS-DICHLOROETHYLENE IN THE MICROWAVE-FREQUENCY REGION

1967 ◽  
Vol 45 (5) ◽  
pp. 1617-1620
Author(s):  
G. P. Srivastava ◽  
P. C. Mathur
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Microwave Frequency ◽  
Frequency Region ◽  
Complex Dielectric Constant ◽  
Dilute Solutions ◽  
X Band

The relaxation time and dipole moment of cis-dichloroethylene has been determined in the X-band microwave-frequency region from its dilute solutions in a nonpolar solvent. The dielectric loss tangent δ is found to vary linearly with concentration only for very dilute solutions.

Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete

1997 ◽  
Vol 503 ◽  
Author(s):  
B. K. Diefenderfer ◽  
I. L. Al-Qadi ◽  
J. J. Yoho ◽  
S. M. Riad ◽  
A. Loulizi
Keyword(s):  
Dielectric Constant ◽  
Portland Cement ◽  
Electromagnetic Waves ◽  
Low Cost ◽  
Complex Dielectric Constant ◽  
Life Cycle Costs ◽  
Parallel Plates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Set Up

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.

scholarly journals Machine-Learning Classification of Soil Bulk Density in Salt Marsh Environments

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4408
Author(s):  
Iman Salehi Hikouei ◽  
S. Sonny Kim ◽  
Deepak R. Mishra
Keyword(s):  
Machine Learning ◽  
Remote Sensing ◽  
Salt Marsh ◽  
Bulk Density ◽  
Remote Sensing Data ◽  
Soil Bulk Density ◽  
Soil Samples ◽  
Marsh Soil ◽  
Landsat 7 ◽  
Salt Marsh Soil

Remotely sensed data from both in situ and satellite platforms in visible, near-infrared, and shortwave infrared (VNIR–SWIR, 400–2500 nm) regions have been widely used to characterize and model soil properties in a direct, cost-effective, and rapid manner at different scales. In this study, we assess the performance of machine-learning algorithms including random forest (RF), extreme gradient boosting machines (XGBoost), and support vector machines (SVM) to model salt marsh soil bulk density using multispectral remote-sensing data from the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) platform. To our knowledge, use of remote-sensing data for estimating salt marsh soil bulk density at the vegetation rooting zone has not been investigated before. Our study reveals that blue (band 1; 450–520 nm) and NIR (band 4; 770–900 nm) bands of Landsat-7 ETM+ ranked as the most important spectral features for bulk density prediction by XGBoost and RF, respectively. According to XGBoost, band 1 and band 4 had relative importance of around 41% and 39%, respectively. We tested two soil bulk density classes in order to differentiate salt marshes in terms of their capability to support vegetation that grows in either low (0.032 to 0.752 g/cm3) or high (0.752 g/cm3 to 1.893 g/cm3) bulk density areas. XGBoost produced a higher classification accuracy (88%) compared to RF (87%) and SVM (86%), although discrepancies in accuracy between these models were small (<2%). XGBoost correctly classified 178 out of 186 soil samples labeled as low bulk density and 37 out of 62 soil samples labeled as high bulk density. We conclude that remote-sensing-based machine-learning models can be a valuable tool for ecologists and engineers to map the soil bulk density in wetlands to select suitable sites for effective restoration and successful re-establishment practices.

MEASUREMENT OF THE COMPLEX DIELECTRIC CONSTANT OF LIQUIDS AT CENTIMETER AND MILLIMETER WAVELENGTHS

1957 ◽  
Vol 35 (9) ◽  
pp. 995-1003 ◽  
Author(s):  
A. G. Mungall ◽  
John Hart
Keyword(s):  
Dielectric Constant ◽  
Methyl Alcohol ◽  
Free Space ◽  
Normal Incidence ◽  
Complex Dielectric Constant ◽  
Families Of Curves ◽  
Millimeter Wavelengths ◽  
Centimeter Wave ◽  
Space Technique ◽  
Wave Region

The measurement of the complex dielectric constant of lossy liquids in the millimeter and centimeter wave region by a free-space technique is described. The method involves the measurement of absorption per wavelength and of reflectance at normal incidence. Families of curves are given for the relations between these two quantities and the real and imaginary parts of the complex dielectric constant. Results for ethyl and methyl alcohol at 9 and 13 mm. wavelength are compared with those obtained by waveguide techniques.

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