Electrical impedance variation with water saturation in rock

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Qingxin Su ◽  
Qining Feng ◽  
Zuoyuan Shang
Keyword(s):  
Electrical Impedance ◽  
Critical Frequency ◽  
Water Saturation ◽  
Characteristic Length ◽  
Interfacial Polarization ◽  
Dissipation Factor ◽  
Frequency Range ◽  
Impedance Variation ◽  
Electrode Method ◽  
Argand Plot

We measured the electrical impedances of 22 sandstone samples during oil‐driving‐water tests using the two‐electrode method. Experiments show that the imaginary part X of the impedance (R + iX) of rock may respond well to water saturation in the frequency range 100 Hz–15 MHz. We found that the maximum −X values and their corresponding interfacial polarization frequencies are linear with water saturation. The lower critical frequency is found to vary with water saturation, in an unclear relationship with the characteristic length of rock. The dissipation factor at the interfacial polarization frequency remains quite stable and may be an indicator of the pore structure of rock. We used an equivalent circuit to explain the dispersive behavior of rock. More than one interfacial polarization frequency in the impedance Argand plot is predicted and can be observed if the measurement frequency range is wide enough.

scholarly journals Design of Reconfigurable Time-to-Digital Converter Based on Cascaded Time Interpolators for Electrical Impedance Spectroscopy

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1889
Author(s):  
Sounghun Shin ◽  
Yoontae Jung ◽  
Soon-Jae Kweon ◽  
Eunseok Lee ◽  
Jeong-Ho Park ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
High Frequency ◽  
Electrical Impedance ◽  
Phase Error ◽  
Electrical Impedance Spectroscopy ◽  
Time Range ◽  
Digital Converter ◽  
Frequency Range ◽  
Input Time ◽  
Interpolation Factor

This paper presents a reconfigurable time-to-digital converter (TDC) used to quantize the phase of the impedance in electrical impedance spectroscopy (EIS). The TDC in the EIS system must handle a wide input-time range for analysis in the low-frequency range and have a high resolution for analysis in the high-frequency range. The proposed TDC adopts a coarse counter to support a wide input-time range and cascaded time interpolators to improve the time resolution in the high-frequency analysis without increasing the counting clock speed. When the same large interpolation factor is adopted, the cascaded time interpolators have shorter measurement time and smaller chip area than a single-stage time interpolator. A reconfigurable time interpolation factor is adopted to maintain the phase resolution with reasonable measurement time. The fabricated TDC has a peak-to-peak phase error of less than 0.72° over the input frequency range from 1 kHz to 512 kHz and the phase error of less than 2.70° when the range is extended to 2.048 MHz, which demonstrates a competitive performance when compared with previously reported designs.

scholarly journals Relationship between moisture content and electrical impedance of carrot slices during drying

2015 ◽  
Vol 29 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Ákos Kertész ◽  
Zuzana Hlaváčová ◽  
Eszter Vozáry ◽  
Lenka Staroňová
Keyword(s):  
Moisture Content ◽  
Electrical Impedance ◽  
Fruits And Vegetables ◽  
Physiological State ◽  
Impedance Measurement ◽  
Biological Tissues ◽  
Impedance Spectra ◽  
Frequency Range ◽  
Impedance Parameters ◽  
Precision Balance

Abstract Electrical properties of food materials can give information about the inner structure and physiological state of biological tissues. Generally, the process of drying of fruits and vegetables is followed by weight loss. The aim of this study was to measure the impedance spectra of carrot slices during drying and to correlate impedance parameters to moisture content in different drying periods. Cylindrical slices were cut out from the carrot root along the axis. The slices were dried in a Venticell 111 air oven at 50°C. The weight of the slices was measured with a Denver SI-603 electronic analytical and precision balance. The weighing of the samples was performed every 30 min at the beginning of drying and every 60 min after the process. The moisture content of the samples was calculated on wet basis. The magnitude and phase angle of electrical impedance of the slices were measured with HP 4284A and 4285A precision LCR meters in the frequency range from 30 Hz to 1 MHz and from 75 kHz to 30 MHz, respectively, at voltage 1 V. The impedance measurement was performed after weighting. The change in the magnitude of impedance during drying showed a good correlation with the change in the moisture content.

scholarly journals Импедансная спектроскопия электропроводящих композиционных материалов на основе микроволокон сополимера поливинилиденфторида с трифторэтиленом, модифицированных полипирролом

2021 ◽  
Vol 47 (11) ◽  
pp. 51
Author(s):  
В.М. Капралова ◽  
И.Ю. Сапурина ◽  
Н.Т. Сударь ◽  
А.А. Третьяков ◽  
O. Gryshkov ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Electrical Impedance ◽  
Impedance Spectra ◽  
Frequency Range ◽  
Dielectric Characteristics ◽  
Circular Arc ◽  
Nanocomposite Polymer ◽  
Nanocomposite Polymer Electrolyte ◽  
Nonwoven Materials ◽  
Composite Nonwoven

The impedance spectra of composite nonwoven materials based on nano- and microfibers of polyvinylidene fluoride-trifluoroethylene copolymer modified by polypyrrole with different doping degree were studied in the frequency range 1000 Hz-5 MHz. It was found that an increase in the doping degree of polypyrrole coating of nanofibers leads to a decrease in the imaginary and real components of the electrical impedance. Regardless of their magnitude, the shape of the hodographs is close to circular arc resting on the ReZ axis, which allows us to consider the studied material as a nanocomposite polymer electrolyte whose dielectric characteristics can be reversibly changed.

scholarly journals Dynamic model of control of vibration damping mode by fiber optic PEL-sensor with phase shifting of control electric voltage.

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
A.A. Pan'kov ◽  
Keyword(s):  
Optical Fiber ◽  
Dynamic Model ◽  
Electrical Impedance ◽  
Coherent Control ◽  
Mechanical Energy ◽  
Light Flux ◽  
Electric Circuit ◽  
Phase Shifting ◽  
Frequency Range ◽  
Electric Voltage

A mathematical dynamic model of the operation of the vibration pressure optical fiber piezoelectroluminescent (PEL) sensor in the damping mode was developed taking into account the electrical conductivities and Maxwell-Wagnerian relaxation of electric fields in the phases for the case of harmonic stress (vibration pressure) on the external cylindrical surface of the sensor. Analytical solution of damping of stationary axisymmetric oscillations of optical fiber PEL-sensor is obtained and investigated by applying coherent control electric voltage to electrodes of sensor with phase shifting relative to vibration pressure. Regularities of frequency dependencies for real, imaginary parts of control, informative transfer and damping coefficients of sensor are established and studied. Analysis of influence of value and shift angle of phases of control electric voltage on results of numerical simulation for intensity of light flux at output from optical fiber of sensor under action of vibration pressure is performed. Frequency dependencies were found for the electrical impedance of the AC electric circuit of the sensor in comparison with the approximation of these dependencies by electromechanical analogy. It was revealed that in the frequency range under consideration, the electrical impedance of the sensor with satisfactory accuracy is based on consideration of an equivalent electric circuit with parallel connection of frequency-dependent active and capacitive elements. Frequency range and values of control parameters are set for effective active damping of vibration pressure through conversion to Joule heat (dissipation) of mechanical energy supplied to the sensor. The results of comparing the analytical and numerical (in the ANSYS package) approaches confirm the validity and adequacy of the decisions obtained.

scholarly journals Fish quality investigations using electrical impedance spectroscopy: preliminary results

2021 ◽  
Vol 2008 (1) ◽  
pp. 012008
Author(s):  
L G Teixeira ◽  
P Bertemes-Filho ◽  
M. Keith Cox
Keyword(s):  
Quality Control ◽  
Impedance Spectroscopy ◽  
Predictive Models ◽  
Oreochromis Niloticus ◽  
Electrical Impedance ◽  
Electrical Impedance Spectroscopy ◽  
Frequency Range ◽  
Long Period ◽  
Capacitive Reactance ◽  
Over Time

Abstract The consumption of seafood has increased over the last 10 years. This article analyses impedance changes of tilapia (Oreochromis niloticus) sample measured over 36 hours by using electrical impedance spectroscopy (EIS). It was also investigated the correlations between variables in order to predictive models to degradation studies. Measurements were collected every 12 hours in order to verify any change due to deterioration. The results show that measurements in both longitudinal and transverse axes are equivalent and that the sample undergoes gradual variations in the impedance. The first set of data collected in the frequency range from 0.1 to 1,000 kHz showed that resistance varied from 310.9 (@ 0.1 kHz) to 86.8 Ω (@1 MHz) and capacitive reactance varied from -8.6 to 11.5 Ω, respectively. The forth set of data showed a decrease of 79.3% (@0.1 kHz) in the resistance part of the impedance, whereas 98.8% in capacitive reactance at 0.1 kHz. These results might suggest that there was a nutritional loss of the sample over time. Further experiments must be done over a long period of time in order to fully understand the process. EIS might be pointed out as a potential technique for fish shelf live quality control.

scholarly journals Freezing resistance evaluation of rose stems during frost dehardening using electrical impedance tomography

2020 ◽  
Author(s):  
Ji Qian ◽  
Juan Zhou ◽  
Juan Rui Gong ◽  
Yang Liu ◽  
Gang Zhang
Keyword(s):  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Freezing Resistance ◽  
Impedance Tomography ◽  
Abiotic And Biotic Stresses ◽  
Biotic Stresses ◽  
Impedance Variation ◽  
Destructive Measurement ◽  
Non Destructive ◽  
Best Fit

Abstract Background Electrical impedance tomography (EIT) has rarely been applied in plant science, particularly to study plant resistance to abiotic and biotic stresses. In this study, we evaluated the freezing resistance of floribunda roses (Rosa Floribunda) during frost dehardening using the EIT technique to identify a new method for rapid and non-destructive measurement of plant freezing resistance. Results The current was the excitation source, the boundary voltage value was measured, and then the boundary voltage reconstructed value was formed. Using an imaging algorithm, the two-dimensional (2D) distribution of impedance or impedance variation is reconstructed. The EIT reconstructed values decreased obviously with the decline in freezing temperatures. The EIT reconstructed values of stems had the best fit to the logistic equation, and subsequently, the semi-lethal temperatures were calculated. The freezing resistance results evaluated using EIT reconstructed values were linearly correlated with the results of the traditional electrolyte leakage (EL) method (r = 0.93, P<0.01). Conclusions In conclusion, after freezing tests, the reconstructed values of EIT images could be used to quantitatively evaluate the freezing resistance of floribunda rose stems. The present study provides a reference for the further application of the EIT technique for non-destructive and rapid detection of plant freezing resistance.

Electrical conductivity and dielectric relaxation studies of biocomposites based on green microcrystalline cellulose-reinforced vinyl resin matrix

2019 ◽  
Vol 53 (20) ◽  
pp. 2801-2808 ◽  
Author(s):  
L Kreit ◽  
I Bouknaitir ◽  
A Zyane ◽  
M El Hasnaoui ◽  
M E Achour ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Glass Transition ◽  
Microcrystalline Cellulose ◽  
Interfacial Polarization ◽  
Relaxation Frequency ◽  
Resin Matrix ◽  
Matrix Interface ◽  
Frequency Range ◽  
Low Frequencies ◽  
Dielectric Relaxations

The dielectric properties of biocomposite materials based on vinyl resin filled with microcrystalline cellulose, in the frequency range from 100 Hz to 1 MHz and in the temperature range from 280 to 400 K, are presented. Two dielectric relaxations were identified. The first one is attributed to the α-relaxation, associated with the glass transition of biocomposite, and the second one, appearing above the glass transition and at low frequencies, was identified as the interfacial polarization effect, which is attributed to the accumulation of charges at the cellulose microcrystalline/matrix interface. Furthermore, the thermal analysis of their relaxation frequency and the electrical conductivity behaviors showed that the activation energy of these composite is more pronounced for the temperatures above the glass transition temperature, suggesting that the interaction between MCC particles and polymeric matrix became significant with the increase of temperature.

scholarly journals Permittivity and Loss of Composites of Epoxy Resin and Kevlar Fibres

1995 ◽  
Vol 4 (4) ◽  
pp. 096369359500400 ◽  
Author(s):  
G.M. Tsangaris ◽  
G.C. Psarras
Keyword(s):  
Dielectric Permittivity ◽  
Epoxy Resin ◽  
Filler Content ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Dielectric Behaviour ◽  
Frequency Range ◽  
Wide Range ◽  
Dielectric Permittivity And Loss

The dielectric behaviour of composites with epoxy resin and kevlar fibres is investigated in a wide range of frequency and temperature. Dielectric permittivity is increasing with filler content and temperature, being always higher in the low frequency range. Dielectric permittivity and loss of the composites is mostly affected by interfacial polarization arising from inhomogeneities at interfaces introduced by the filler.

scholarly journals Investigation on Electrical Properties of Solid Polymer Sheets (HDPE AND LDPE) at Audio Frequency Range

2021 ◽  
Keyword(s):  
Relaxation Time ◽  
Electrical Properties ◽  
Dissipation Factor ◽  
Solid Polymer ◽  
Electrical Modulus ◽  
Audio Frequency ◽  
Frequency Range ◽  
Polymer Sheets ◽  
Dielectric Cell ◽  
Audio Frequency Range

Two different groups of solid polymer sheets: low density polyethylene (LDPE) sample of thickness 0.006 cm and 0.007 cm along with high density polyethylene (HDPE) sample of the thickness of 0.009 cm, 0.010 cm were taken in this work. The measurement of electrical properties such as dielectric constant, ε' and dielectric loss, ε'' for LDPE and HDPE polymer sheets have been measured using a dielectric cell. The dielectric cell has been fabricated which consists of two circular parallel plates of pure stainless steel each of 5 cm diameter and 2 mm thickness. An impedance bridge (GRA 650A) was used for measurement of capacitance, C, and dissipation factor, D in the audio frequency (AF) range, 100 Hz to 10 kHz. Different samples were loaded in between the two plates of the cell and the capacitance as well as the dissipation factor were estimated from the dial readings of the bridge. Effect of frequency variation on ε', ε'', relaxation time, τ , dissipation factor, tanδ and ac conductivity, σ were also discussed at audio frequency range. The complex permittivity, ε*, related to free dipole oscillating in an alternating field and loss tangent, tanδ were calculated. The frequency-dependent conductivity, dielectric behavior, and electrical modulus, both real (M') and imaginary (M") parts of LDPE and HDPE have been studied in this work. The values of the real part of the electrical modulus (M') did not equal to zero at low frequencies and it is expected that the electrode polarization may develop in both sheets. These findings reveal an increased coupling among the local dipolar motions in a short-range order localized motion. The analysis of real (ε') and imaginary (ε'') parts of dielectric permittivity and that electrical modulus real (M') and imaginary (M") parts signify poly dispersive nature of relaxation time as observed in Cole-Cole plots.

Thermal, mechanical, and dielectric properties of epoxy resin modified using carboxyl-terminated polybutadiene liquid rubber

2016 ◽  
Vol 49 (4) ◽  
pp. 281-297 ◽  
Author(s):  
Lina Dong ◽  
Wenying Zhou ◽  
Xuezhen Sui ◽  
Zijun Wang ◽  
Peng Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Dissipation Factor ◽  
Wide Frequency Range ◽  
Carboxyl Groups ◽  
Frequency Range ◽  
Two Phase ◽  
Liquid Rubber ◽  
The Impact ◽  
Thermal Stability Of

Epoxy (Ep) resin modified with carboxyl-terminated polybutadiene (CTPB) liquid rubber was investigated in this study. Fourier transform infrared verified the chemical reactions between oxirane ring of Ep and carboxyl groups of CTPB using benzyldimethylamine as a catalyst. The decrease of the thermal stability could be due to the lower thermal stability of CTPB compared with that of pure Ep. The mechanical results showed that CTPB-modified Ep was superior to that of the pure Ep, and the best overall mechanical properties were normally achieved with 20 phr of CTPB content. The impact strength of the system containing 20 phr CTPB increased by 193% due to the two-phase nature of the system. The dielectric constant and dissipation factor of the modified Ep obviously declined with the CTPB content compared with pure Ep, for instance, the dissipation factor remained less than 0.02 in wide frequency range.

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