Accuracy Analysis of Transmission Phase-Shift Method for Material Characterization

Electromagnetic (EM) waves are used in the oil and gas industry to identify the geology of the formation and the type of the fluid saturating the medium. There is also an interest to use the electromagnetic waves as an enhanced oil recovery (EOR) method. However, interpretation of logging data generated through electromagnetic waves or determination of the electromagnetic wave propagation in a medium as an EOR method are not easy tasks. This study aims to identify the role of different geological settings with different types of fluid saturations in the response of electromagnetic wave propagation and absorption. To reach this objective multitude-systematic laboratory scale experiments were conducted on different reservoirs fluid and rock pairs. As reservoir mineralogy, different grain size of quartz, clay, or limestone is used to prepare the reservoir rocks at different porosity. Water is known as a good absorber for EM waves, thus, pore space were saturated at different water saturations and a bitumen sample (10,000 cP, 12° API) from Canada. Prepared samples were packed into in-house-built-Plexiglas core holder which allows measurements with EM waves. The response of EM waves propagation and absorption was measured by using a vector network analyzer at varying frequencies (500 MHz to 4 GHz) through dielectric properties (dielectric constant, loss tangent, and penetration depth). The results were used to obtain correlations between dielectric properties and physical properties (reservoir rock mineralogy, porosity, water saturation, and oil saturation) of the reservoir rock-fluid blends. Water saturation gives a perfect correlation with dielectric constant and loss tangent values of the saturated medium. Because dielectric constant and loss tangent parameters provide an idea on the absorption characteristics of EM wave in the medium, and because water is a strong EM wave absorber, as it was expected, with the increase in water saturation, the dielectric constant and loss tangent parameters of the medium are also increased; on the other hand, penetration depth was decreased. With the increase in quartz content in the medium, it has been observed that EM wave penetration is enhanced. As a result, several correlations were created in this study and they can be used to better interpret the reservoir mineralogy and fluid saturation as a response to EM wave logging. Moreover, these results can be used to estimate the effective area (penetration depth) of EM wave as an EOR method in different mediums.

Dielectric properties of foods are used to explain interactions of foods with electric fields. It determines the interaction of electromagnetic waves with matter and defines the charge density under an electric field. For engineering point of view, dielectric properties are the foremost important physical properties related to radio frequency and microwave heating, it is critical to possess knowledge of the dielectric properties of materials in products and process development and, within the modern design of dielectric heating system for the need of desired process. Dielectric properties are often categorized into two: dielectric constant and dielectric loss factor. Dielectric constant is the ability of a material to store microwave energy and dielectric loss factor is the ability of a material to dissipate microwave energy into heat. Dielectric properties of food materials are required for various applications in food industry like microwave (at 915 or 2450 MHz), radio wave (at 13.56, 27.12 or 40.68 MHz) and magnetic field processing. In this review, the dielectric properties of various food groups were listed such as; Cereal grains and oilseeds, Bakery product, Dairy products, Poultry products, Fruits and vegetables. Dielectric properties are utilized in fruit drying processes, protect food materials from insects that already present in dried fruits, pasteurization, sterilization, tempering of concentration of liquid foods such as fruit juices, identification, processing, quality monitoring of fats and oils and improvement during oil processing and storage. The dielectric studies of food materials are an important tool to identify the quality of food materials and to improve dielectric heating uniformity. Frequency, moisture content, phase change, storage time and temperature are main factors that influence the dielectric properties of food material.

This study for the first time reports the processing and properties of high‐density polyethylene (HDPE) reinforced with niobium pentoxide (Nb2O5) up to 40 wt%. In this work, Nb2O5 was chosen as reinforcement because of its advantageous properties such as good dielectric properties, high temperature stability and excellent biocompatible properties. Almost fully dense HDPE–Nb2O5 composites were prepared via hot pressing route. Both the hardness and dielectric properties of the HDPE increased significantly with the addition of Nb2O5. The hardness of HDPE increased from ∼37 to 60 MPa (i.e., by 62%) with the addition of 40 wt% Nb2O5. The dielectric constant and dissipation factor (dielectric loss) were found to increase with the increasing Nb2O5 content. We have achieved highest ever reported dielectric constant (ε') of 14.66 for HDPE–40 wt% Nb2O5 and the dielectric constant of HDPE is enhanced by 237% and shows the potential of Nb2O5 in improving the dielectric and hardness properties of HDPE. With increasing frequency there was slight decrease in the dielectric constant of HDPE–Nb2O5 composites, whereas not much change in the dielectric constant of pure HDPE. The dielectric constant (ε') of HDPE is 4.6 at 1 MHz, while the ε' value for the composite with 40 wt% Nb2O5 ceramic filler was found to be 13.2. The dielectric loss for the HDPE composites is higher than the neat polymer, particularly HDPE–40 wt% Nb2O5 composite measured with maximum dielectric loss (0.08) at 100 Hz. Nevertheless, the dielectric loss of HDPE materials significantly decreased with further increasing the frequency to 1 kHz and the dielectric loss even significantly lowered with increasing frequency to 1 MHz. The experimental values of dielectric constant show much better values than the calculated values based on theoretical models. The newly developed HDPE–Nb2O5 composites are showing much better dielectric properties than the reported literature values of HDPE materials. POLYM. COMPOS., 40:749–757, 2019. © 2018 Society of Plastics Engineers

Effect of water and chloride contents and carbonation on the electromagnetic characterization of concretes on the GPR frequency band through designs of experiment

Grain size effect on the dielectric and non-ohmic properties of CaCu3Ti4O12 ceramics prepared by the sol-gel process

Ferroelectric/metal composites have been characterized for their electric field dependence of the dielectric and ferroelectric properties. The composites show an interesting change of dielectric properties with increasing metal concentration. A relatively high dielectric constant, up to four times as high as that of monolithic lead zirconate titanate (PZT), is observed in the investigated composition range. The dielectric properties are clearly electric field dependent. The tunability of the composite, defined as the difference between the dielectric constant with no applied voltage and the dielectric constant with an applied voltage, divided by the dielectric constant with no applied voltage, was found to be ∼17, whilst for the monolithic PZT ceramics it is about 3 only. This offers perspectives for application of these composites in lighting electronics and voltage controllers. Ferroelectric hysteresis measurements on these composites revealed a square-shaped hysteresis loop with remnant polarization comparable with single PZT ceramics, while the coercive field was much lower than that of pure PZT ceramics. This might be interesting for application of these composites as a ferroelectric memory material with decreased switching voltage.

Computer modeling of the dielectric properties of the cucurbit [7]uril (CB[7]) cavity  based on the Onsager-Liptay model was carried out by analyzing the solvatochromic shift of the absorption spectrum of 1- (3ammoniumpropyl) -4 - [(E) -2- (3,4-dimethoxyphenyl) ethynyl]pyridinium upon the formation of the inclusion complex with CB[7] in a water solution. The CB[7] cavity was considered as a polar environment into which the dye chromophore is placed. Positions of the maxima of the dye absorption spectra were measured experimentally in the following solvents: methanol, ethanol, i-propanol, n-butanol and water with known dielectric and optical properties. These values were used for parametrization of the Onsager-Liptay equation. Quantum-chemical calculations were used to determine molecular structures, dipole moments of the ground and excited states, and polarizability of the dye.  Theoretical value of the effective dielectric permittivity of the cavity is in good agreement with the literature data derived by another method. Also, we investigated the preferential solvation effect of pyridinium-N-phenolate betaine (organic dye) taken as a molecular probe in two binary solvents (water-BuOH and water-BuNH2) in concentration range 0-100%. The spectral solvatochromic shift in the dye's solvation shell and the environment's dielectric permittivity were linked using the aforementioned Onsager-Liptay model. It was demonstrated that the second component of the binary solvent in water solution greatly depletes the dye's solvation shell. Both the water-BuOH and water-BuNH2 solvents exhibit this property. The water-BuNH2 solvent scenario exhibits a higher absolute spectral shift than the second case. However, in the case of water-BuOH, the relative depletion is greater. Thus, we propose a new method for investigation the dielectric constant both in bulk liquids and in very small liquid volumes. The method's unique potential lies in the creation of nanoprobe devices that may be used to test the dielectric constant of small objects and nano-regions and to adjust the instantaneous solvent concentration in evaporating sessile droplets of binary solvent in various zones of the droplet.

With the development of electronic components towards miniaturization and integration, permittivity, permeability, loss tangent and other microwave parameters have become the characteristics of new microwave materials. The relative complex permittivity and relative magnetic permeability of solid materials are the most important for microwave electrical elements, componentsor antennas design. In this paper we introduce the method of measuring relative complex permittivity and relative magnetic permeability of solid materials at 30MHz∼50GHz frequencies using air coaxial line and waveguide. The paper describes how to make phase compensation to solve the issue brought by the calibration of the network analyzer and how to re-calculate the S parameters using phase compensation technology.

ABSTRACTFabrication of hybrid composite of nickel oxide (NiO) combined with oil palm empty fruit bunch (OPEFB) reinforced with polycaprolactone (PCL) has been done by using thermal Haake blending machine, which ensured mixture homogeneity. All hybrid composites' characterizations were carried out using X‐ray diffraction (XRD), Fourier transform infrared spectrometry, differential thermogravimetry, thermogravimetric analysis, and scanning electron microscopy. The results showed that the XRD profile patterns of the composites clearly changed as the filler loading amount was increased. Fourier transform infrared spectra illustrated a slight change in the frequencies and positions of the peaks after adding NiO, indicating that some interactions occurred between C=O and O–H or among the fiber, NiO, and PCL. The microwave electromagnetic properties, such as reflection loss (dB), relative complex permittivity (εr =–j), and permeability (−j) were calculated at various microwave frequencies in the X‐band (8–12 GHz) range. It was observed that the thermal stability, magnetic, and dielectric properties of NiO:OPEFB:PCL composites were modified significantly with NiO addition. This enables the new hybrid composites to be used as engineering materials in the microwave applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46998.

This paper presents an experimental and analytical study of irreversible change in piezoelectric wafer active sensor (PWAS) electromechanical (E/M) impedance and admittance signature under high temperature exposure. After elevated to high temperatures, change in the material properties of PWAS can be quantified through irreversible changes in its E/M impedance and admittance signature. For the experimental study, circular PWAS transducers were exposed to temperatures between 50 °C and 250 °C at 50 °C intervals. E/M impedance and admittance data were obtained before and after each heating cycle. Irreversible temperature sensitivity of PWAS resonance and anti-resonance frequency was estimated as 0.0246 kHz °C−1 and 0.0327 kHz °C−1 respectively. PWAS transducer material properties relevant to impedance or admittance signature such as dielectric constant, dielectric loss factor, mechanical loss factor, and in plane piezoelectric constant were determined experimentally at room temperature before and after the elevated temperature tests. The in-plane piezoelectric coefficient was measured by using optical-fiber strain transducer system. It was found that the dielectric constant and in-plane piezoelectric coefficient increased linearly with temperature. Dielectric loss also increases with temperature but remains within 0.2% of initial room temperature value. Change in dielectric properties and piezoelectric constant may be explained by depinning of domains or by domain wall motion. The piezoelectric material degradation was investigated microstructurally and crystallographically by using scanning electron microscope and x-ray diffraction method respectively. There were no noticeable changes in microstructure, crystal structure, unit cell dimension, or symmetry. The degraded PWAS material properties were determined by matching impedance and admittance spectrums from experimental results with a closed form circular PWAS analytical model. Analytical results showed that impedance and admittance strongly depend on elastic coefficient, dielectric constant, mechanical loss factor, dielectric loss tangent and in plane piezoelectric constant. These properties were found to be susceptible to change after high temperature exposure.

It has been established that in order to study thermo- and electrophysical phenomena in wet steam turbines, studies of the wet steam flow volume charge effect on its dielectric and thermophysical properties have recently been carried out at A. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine. According to their results, it was established that the most representative electrophysical parameter, which allows to evaluate changes in the thermophysical properties of steam, which occur under the action of its own volume charge, is its dielectric constant. It is assumed that the value of the dielectric constant of an electrified steam can be significantly different from the value for a neutral steam, and a mathematical assessment of its possible change is made. It has been confirmed that the influence of electrophysical phenomena caused by the wet steam flow electrification is significant, but is not taken into account in the existing physical and mathematical thermodynamic models of the steam expansion process. It is proved that in order to clarify the main thermodynamic parameters and calculated characteristics of the electrified wet steam flow, it is necessary to determine how its dielectric constant changes. On the basis of the analysis, the relevance of experimental determination of the dielectric constant of a wet steam flow with a volume charge in order to obtain the dependence of its change on the temperature and pressure of the flow, as well as the density of the volume charge, is substantiated. To perform the research, a gas dynamic laboratory plant, which allows to obtain a wet steam flow with a volume charge, was used. The internal space of the flow part of a real wet steam turbine has a significant size and allows the formation of a flow with a volume charge of a complex spatial configuration and structure. It is emphasized that in the flow part of the plant of a small volume, in contrast to the turbine flow part, significant technical difficulties arise when organizing the conditions for the occurrence of a wet steam flow with a volume charge. Taking this into account, at the first stage, it was decided to conduct a study of a steam flow with a volume charge flowing into the atmosphere in a laboratory room with a sufficient volume to form its spatial structure. To estimate the value of its dielectric constant, the inductive method (L-method) of determining dielectric properties, in which the substance under study is introduced into the inductive solenoid cell, was chosen. Experiments were conducted and, according to the obtained data, it is possible to make a preliminary assessment of the change in dielectric constant in the presence of a volume electric charge in the steam flow

In the present work BaFe12O19 nano-hexaferrite had been synthesized by sol-gel method and then characterized for its structural, electric, dielectric and magnetic properties. X-ray diffraction studies confirmed the hexagonal structure of the prepared nanohexaferrite with no secondary phase and the particle size was found to be of the order of 49 nm. Further, the morphology of the sample has been studied by using transmission electron microscopy (TEM). A high value of the DC resistivity (5.5 × 10 6 Ω cm), has been obtained at room temperature. The dielectric properties such as dielectric constant (e'), dielectric loss tangent (tan δ) and ac electrical conductivity (σac) are investigated as a function of frequency. The dielectric constant and loss tangent are found to be decreasing with the increase in frequency while ac electrical conductivity is observed to be increasing with the increase in frequency. The dielectric properties have been explained on the basis of Maxwell-Wagner's two-layer model and hopping of the charge. The magnetic properties such as initial permeability (µi) and relative loss factor (RLF) have been investigated as a function of frequency in the range 75 kHz to 30 MHz .Fairly constant value of initial permeability and low values of RLF of the order of 10 -4 over a wide frequency range are the cardinal achievements of the present work. The room temperature M-H study shows that present nanohexaferrite has high value of coercivity (2151.3 Oe) and high saturation magnetization (32.5 emu/gm), which make present nanohexaferrite very suitable for magnetic applications. The M-T study shows that prepared nano-hexaferrite has high Tc (746 K). Copyright © 2014 VBRI press.

Tuning of dielectric and magnetic performance of graphene oxide via defect regulation by metal oxide nanoparticle for high temperature device

A modified level-set method (MLSM) is proposed to simultaneously reconstruct the shape and electrical properties of 2-D objects. As a numerical technique, the formal level-set method (LSM) can retrieve the shape and position of objects, using synthetic/measurement data. In general, the constitutive parameters of an object (e.g., its relative complex permittivity) are among the a priori information needed for the LSM. For MLSM, an evolution strategy is proposed to simultaneously calculate both the shape and complex permittivity of a 2-D object. The initial guesses in respect of the complex permittivity and shape of the target object converge on their real values as the cost function is minimized. The cost function is regularized with two penalty terms. To prevent sudden change in the shape of the object, a curvature-based regularization is used. Also, Laplacian regularizer is used to reduce fluctuations in the object’s constitutive parameters during the process. Using different synthetic data sets, the capabilities of MLSM in microwave imaging and parameter estimation are evaluated. It is found that, using MLSM, it is possible to completely separate two adjacent objects, separated by a distance of one-fifteenth of a wavelength. The proposed method can retrieve targets of different relative permittivities, with less than 10% error. One interesting feature of this method is its high fidelity in retrieving the immersed one-tenth-wavelength targets in highly contrasting (up to as high as 8:1) domains. In the case of targets with little contrast (10%), the proposed method, with more iterations, can converge on a value, which is 57% more than the actual value. These features are valuable in distinguishing malignant tissue from normal tissue.

ABSTRACTNanoporous or mesoporous structures and hence a decrease in dielectric constant can always be induced with the introduction of air into polymeric materials. It is therefore achievable to prepare ultra‐large‐scale integrated circuit (ULSIC) on ultralow dielectric constant (i.e., low‐k) materials. The research on nano/mesoporous polymer based low‐k materials, including the past decade advances, the introduction of principles and methods of nano/mesopores, characterization, commonly used raw materials, typical products, and corresponding dielectric properties, is extensively reviewed and summarized in this paper. The nano/mesopores can be introduced into the polymers by more than five methods such as reprecipitation, sol–gel, thermolysis, supercritical foaming, and electrochemical etch. The pore size, morphologies, porosities, and film thicknesses of the products can be controlled by raw materials and processing conditions in these methods. The low‐k dielectric materials based on nano/mesoporous polymers have great potential application in ULSIC in light of their special dielectric, optical, thermal, and mechanical properties. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21358; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21358