Relative permittivity

Application of a quasi-optical apparatus in the determination of the constituent parameters of materials is presented in this paper. Correction terms are introduced to remove the errors due to the misplacement of the sample and the calibration procedure. Good agreement was observed between manufacturer specifications and measurements after application of the correction terms.

Measurements of the electric conductivity, σ, and
relative dielectric permittivity, εr
, were conducted (0.1Hz  –15
MHz)  on  40 air-dried  soil samples that were subsequently
analyzed for pH, total organic matter in soil (ΔM/m1), P2O5,    ,
Fe2O3 and heavy metal concentrations (Pb, Cd, Cr, Ni, Cu и Zn).
The pH of soil samples varied between pH 5.25 and pH 7.73
(mean pH 6.71), the ΔM/m1 varied between 1,49 % and 9.96 %
(mean 4.56 %). The mean content of Fe2O3 was 44352.5 mg/kg,
which was 114 fold higher than the mean concentration of the
heavy metals (Pb, Cd, Cr,  Ni, Cu и  Zn).  The mean content of
P2O5 was 0.26% . We found a linear relation between σ (1 MHz)
and the indicated physicochemical parameters; P2O5 (coefficient
of correlation, r = 0.637), рН (R = 0.530 ) ,  Fe2O3 concentration
(r =  0.450), content of ΔM/m1 (r =  0.545) and heavy metal
concentration (r =  0.460). Similar relationships and  correlation
coefficients were found between εr (10  kHz) and the same
physicochemical parameters. As the latter represent general
biogeochemical parameters, our findings suggest that  dielectric
spectroscopy  may provide  useful approach to probing soil
geochemistry, iron cycling and anaerobic microbial activity.
Furthermore, our results yield insights into the impact of various
physicochemical parameters on the induced polarization of soils.

Precise measurements on the electrical conductivity of solutions of sodium polystyrenesulphonate in methanol–water mixed solvent media containing 8, 16, 25, and 34 wt.% of methanol at 308.15, 313.15, 318.15, and 323.15 K are reported. The degree of substitution of sodium polystyrenesulphonate used was 1, and the concentrations were varied from ∼2.0 × 10−4 to ∼4.0 × 10−3 monomol l−1. The results showed a slight and monotonous increase in the equivalent conductivity with decreasing polyelectrolyte concentration. The applicability of the Manning’s theory for salt-free polyelectrolyte solution was examined and a major discrepancy against the theory was observed. The calculated values of the equivalent conductivity deduced on the basis of this theory were found to be lower than the experimental ones. Possible reasons for this discrepancy have been discussed. The effects of the temperature and relative permittivity of the medium on the equivalent conductivity were also investigated. Estimation of the fractions of uncondensed counterions provides important insight regarding the solution behavior of the polyelectrolyte in methanol–water mixtures.

To detect partial discharges (PD) in equipment such as gas insulated substations and power transformers, UHF couplers can often be fitted at dielectric apertures (windows) in the metal cladding. Waveguide theory is used to show how the window structure affects PD detection sensitivity in the UHF band. By increasing the relative permittivity of the propagation medium, the effective diameter of the window can be increased, leading to improved UHF signal transfer. A given sensitivity to PD can therefore be achieved using a smaller, more robust window, which is particularly important when the insulation is a liquid or gas under pressure. Alternatively, if the window size is fixed, filling it entirely with a dielectric material can improve PD detection sensitivity. A window designed specifically for coupling UHF signals is proposed as an alternative to the use of internal couplers.

Post-harvest deterioration of sugarcane quality is one of the major issues that affect sugar production in sugar industries. There is a need for an effective technique that could quickly measure sugarcane quality without pre-processing the sugarcane stalks. This study was intended to create a capacitance-based setup capable of predicting °brix through non-destructive testing. The setup measures relative permittivity values which along with weight is used to predict the value of °brix in sugarcane stalks. A 5V sinusoidal wave of 5 different frequencies in the range 1 kHz-1 MHz was swept across the parallel plate capacitor with sugarcane stalk samples as the dielectric medium. A total of three hundred stalks from four commercial varieties of sugarcane (CO 95020, CO 86010, CO 86032 and CO 06022) were used for the analysis. A predictive model for °brix was built using multiple linear regression, random forest and artificial neural networks. Feature selection revealed that relative permittivity at 1kHz frequency and weight were highly capable of predicting °brix. The best prediction was obtained from the random forest model with a coefficient of determination (Rv 2) of 0.942.

A state of the art modeling of microwave photoswitching devices is exposed. A new 3 D electromagnetic modeling allows the design of an optically-controlled microwave phase shifter microwave starting from the traditional circuit of a microwave photoswitch. Measurements of the parameters S of this optically-controlled microwave phase shifter attests the function of this circuit by optical way and highlights the