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1
Buzunova, M. Yu. "Dielectric losses under heat treatment of dispersed media." Proceedings of Irkutsk State Technical University 24, no. 6 (2021): 1223–31. http://dx.doi.org/10.21285/1814-3520-2020-6-1223-1231.
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The purpose of the paper is to study the dependence of dielectric losses of mechanically activated grain crops on example of wheat under heat treatment on temperature and external electric field frequency as well as to examine the effect of particle size of fine grain samples on grain electrophysical characteristics and dielectric losses. Experimental samples of dispersed systems with particle sizes in the range from 50 to 1000 μm are prepared by the method of mechanical activation. The temperature dependence of the dielectric loss angle tangent is measured using the dielectric method over a wide frequency range. The dependence of the dielectric loss angle tangent tgδ of mechanically activated wheat samples with the different degrees of particle dispersion in a wide temperature range from 20°C to 250°C with a heating rate of 0.7 deg/min is studied. It is found out that the external electric field frequency varies in the range from 25 Hz to 106 Hz. Electric capacitance and conductivity are measured using an E7-20 immitance meter and a specially designed measuring cell. Dielectric characteristics are calculated. Experimental data are presented in the form of graphs and diagrams. We have determined the correlation of the tangent of the dielectric loss angle tgδ with the frequency of the external electric field and temperature, which is most characteristic for fine samples. The most finely dispersed samples with a particle size of less than 50 microns are shown to have high electrical activity. Increase in the dielectric permittivity and the tangent of the dielectric loss angle is most noticeable at the frequencies below 100 Hz. The study of dielectric characteristics allows to choose an effective energy-saving drying mode of the crop under study.
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Bezprozvannych, G. V., and M. V. Grynyshyna. "Effective parameters of dielectric absorption of polymeric insulation with semiconductor coatings of power high voltage cables." Electrical Engineering & Electromechanics, no. 3 (May 30, 2022): 39–45. http://dx.doi.org/10.20998/2074-272x.2022.3.06.
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Introduction. The presence of semiconductor shields leads to additional dielectric losses compared to polymer insulation without shields. Losses in cables in the presence of semiconductor coatings depend on the dielectric permittivity and resistivity of the composite polymeric material, which are frequency-dependent characteristics. Purpose. To determine in a wide range of frequencies, taking into account the variance of electrophysical characteristics and thickness of semiconductor shields effective electric capacitance and tangent of dielectric losses angle of high-voltage power cables with polymer insulation. Methodology. Serial-parallel nonlinear circuit replacement of semiconductor coatings and linear polymer insulation to determine in a wide range of frequency the effective parameters of the dielectric absorption of a three-layer composite system of high-voltage power cables of single core. Practical value. The obtained relations are the basis for the development of practical recommendations for substantiating the thickness and electrophysical parameters of semiconductor shields to reduce the impact on the effective tangent of the dielectric losses angle of a three-layer composite system of high-voltage power cables.
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G., V. Bezprozvannych, and V. Grynyshyna M. "Effective parameters of dielectric absorption of polymeric insulation with semiconductor coatings of power high voltage cables." Electrical Engineering & Electromechanics, no. 3 (May 30, 2022): 39–45. https://doi.org/10.20998/2074-272X.2022.3.06.
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<strong><em>Introduction</em></strong><em>. The presence of semiconductor shields leads to additional dielectric losses compared to polymer insulation without shields. Losses in cables in the presence of semiconductor coatings depend on the dielectric permittivity and resistivity of the composite polymeric material, which are frequency-dependent characteristics. <strong>Purpose.</strong> To determine in a wide range of frequencies, taking into account the variance of electrophysical characteristics and thickness of semiconductor shields effective electric capacitance and tangent of dielectric losses angle of high-voltage power cables with polymer insulation. <strong>Methodology. </strong>Serial-parallel nonlinear circuit replacement of semiconductor coatings and linear polymer insulation to determine in a wide range of frequency the effective parameters of the dielectric absorption of a three-layer composite system of high-voltage power cables of single core. <strong>Practical value.</strong> The obtained relations are the basis for the development of practical recommendations for substantiating the thickness and electrophysical parameters of semiconductor shields to reduce the impact on the effective tangent of the dielectric losses angle of a three-layer composite system of high-voltage power cables.</em>
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Machulyanskyy, A. V., D. D. Tatarchuk, O. V. Telychkyna, and T. L. Volkhova. "Dielectric Characteristics of Composite Materials based on carbon." Electronics and Communications 16, no. 2 (2011): 39–41. http://dx.doi.org/10.20535/2312-1807.2011.16.2.268398.
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Dependences of complex dielectric permitivity and tangent of dielectric losses angle are explored in the range of temperatures T = 280 - 360 К at the frequencies of 10 GHz and 30 GHz at different concentrations of dispersion phase of carbon in polymeric composite material. It is shown that polymeric composites possesses the least values of temperature coefficient of tangent of dielectric losses angle (nearly 10~5 К 1) with maintenance of carbon more than 20%
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Kostiukov, Ivan, Anatoliy Borysenko, Svitlana Lytvynenko, and Yana Ilchakova. "Diagnostics of power cable insulation by using the methods of dielectric spectroscopy: overview of physical basis and features of practical application." Bulletin of NTU "KhPI". Series: Problems of Electrical Machines and Apparatus Perfection. The Theory and Practice, no. 1 (11) (July 23, 2024): 79–84. http://dx.doi.org/10.20998/2079-3944.2024.1.15.
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The article provides an overview of the physical foundations and features of the application of diagnostic methods for the insulation of power cables using dielectric spectroscopy methods in the frequency and time domains. The relationship between the depolarization currents and the frequency spectrum of the complex dielectric constant is shown. An analysis of the factors determining the frequency dependence of the tangent angle of dielectric losses of paper and polyethylene insulation of power cables is given. The main types of reaction of dielectric materials with different levels of development of water channels at the level and frequency of the applied voltage are listed. According to the results of the analysis, it is shown that for high-voltage measurements, one of the factors that complicates the diagnosis of the insulation of power cables by analyzing the frequency dependences of the capacitance and the tangent of the dielectric loss angle is the distortion of the sinusoidal current through the dielectric due to the nonlinear dependence of the complex dielectric constant on the level of the applied voltage. A comparative analysis of dielectric spectroscopy methods in the frequency domain, involving high-voltage and low-voltage measurements of the complex dielectric constant, was carried out. The correlation between the tangent of the dielectric loss angle of paper insulation and its mechanical characteristics is shown
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Niftiyev, N. N., A. O. Dachdemirov, F. M. Mammadov, and M. B. Muradov. "Frequency dispersion of dielectric coefficients of MnGaInTe4 crystals." Semiconductor Physics, Quantum Electronics and Optoelectronics 27, no. 02 (2024): 189–93. http://dx.doi.org/10.15407/spqeo27.02.189.
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The frequency and temperature dependences of the tangent of dielectric loss angle as well as the real and imaginary part of the dielectric constant of MnGaInTe4 crystals are investigated in the frequency range of 102 to 106 Hz. The experimental values of the studied characteristics are determined. The real and imaginary parts of the permittivity are found to undergo significant dispersion, which has a relaxation nature. The main type of dielectric losses in MnGaInTe4 crystals in the frequency range of 102 to 106 Hz are the electrical conductivity losses. The conductivity is characterized by a zone-hopping mechanism. The activation energies of charge carriers are determined.
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Bezprozvannych, G. V., I. A. Kostiukov, and O. A. Pushkar. "Synthesis of constructive-technological decisions of regulation of working capacitance of cables of industrial networks." Electrical Engineering & Electromechanics, no. 1 (February 23, 2021): 44–49. http://dx.doi.org/10.20998/2074-272x.2021.1.07.
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Introduction. Over the past 10 years, the number of industrial networks has more than doubled. At the physical level, all industrial technology networks are based on twisted pair. Purpose. Synthesis of constructive-technological decisions of regulation of electric capacitance of the insulated conductor at a stage of manufacturing of twisted pair of cables of industrial networks. Methodology. The method of secondary charges to determine the capacitance of the insulated conductor by varying the thickness of the solid and foamed polyethylene insulation. Practical value. Effective regulation is provided on the basis of the obtained dependencies of the effective dielectric constant, the tangent of the dielectric loss angle and the capacitance of the insulated conductor on the degree of foaming and the thickness of the protective film of two-layer insulation. At a degree of porosity of 40 %, the dielectric constant decreases by 25 %, the tangent of the dielectric loss angle – by 33 %, the electrical capacitance of the insulated conductor – by 20 %.
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Buev, S. A. "Analysis of XLPE cable parameters subject to thermo aging." Vestnik MGTU 24, no. 4 (2021): 341–49. http://dx.doi.org/10.21443/1560-9278-2021-24-4-341-349.
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Modern marine vessels use electrically driven rudders; cruise liners, gas carriers, tankers are equipped with Azipod systems manufactured by the Swedish-Swiss company ABB. Gondola-type propellers make it possible to break ice when the vessel is moving astern, therefore such vessels are used for work on the Northern Sea Route, in particular, when working on the Yamal LNG project. The 22MW Azipod propulsion system rotates 360° and enables difficult maneuvering without the assistance of tugs. When operating such propellers, powerful diesel generators are installed on the ship. For the transmission of electricity, ship cables are used, which are subject to increased requirements that meet the standard of the International Electrotechnical Commission. Modern marine vessels are equipped with XLPE or EPDM insulated cable lines; industrial production of these cables is carried out in the Russian Federation. In the course of the study, a method for auditing the state of insulation has been considered based on an assessment of the change in the tangent of the angle of dielectric losses in the process of thermal aging of the cable of the PvBPng(A)-HF brand. Measurements of the tangent of the dielectric losses' angle have been carried out with a Tangens-2000 insulation parameter meter.
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G.V., Bezprozvannych, Kostiukov I.A., and Pushkar O.A. "Synthesis of constructive-technological decisions of regulation of working capacitance of cables of industrial networks." Electrical Engineering & Electromechanics, no. 1 (February 25, 2021): 44–49. https://doi.org/10.20998/2074-272X.2021.1.07.
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<strong><em>Introduction.</em></strong><em> Over the past 10 years, the number of industrial networks has more than doubled. At the physical level, all industrial technology networks are based on twisted pair. <strong>Purpose.</strong> Synthesis of constructive-technological decisions of regulation of electric capacitance of the insulated conductor at a stage of manufacturing of twisted pair of cables of industrial networks. <strong>Methodology.</strong> The method of secondary charges to determine the capacitance of the insulated conductor by varying the thickness of the solid and foamed polyethylene insulation. <strong>Practical value.</strong> Effective regulation is provided on the basis of the obtained dependencies of the effective dielectric constant, the tangent of the dielectric loss angle and the capacitance of the insulated conductor on the degree of foaming and the thickness of the protective film of two-layer insulation. At a degree of porosity of 40 %, the dielectric constant decreases by 25 %, the tangent of the dielectric loss angle – by 33 %, the electrical capacitance of the insulated conductor – by 20 %.</em>
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Torshkhoyeva, Z. S., B. I. Kunizhev, and А. M. Kharaev. "The Investigation of the effect of laser radiation on the dielectric properties of polymethylmethacrylate." E3S Web of Conferences 413 (2023): 02039. http://dx.doi.org/10.1051/e3sconf/202341302039.
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The problem of studying the interaction of laser radiation with polymer materials lies in the study of the effect of intense energy fluxes on matter. The effect of pulsed laser radiation on a high-molecular substance was studied from changes in the electrical parameters of the irradiated materials. Changes in ε’, tg δ depending on the frequency of the external field, the dose of laser irradiation, temperature and time were investigated by a highly sensitive physicochemical method -the method of dielectric losses. This article examined the impact of laser radiation on the dielectric properties of polymethylmethacrylate at frequency of 50 kHz within the temperature interval from 170 to 420 K. The authors showed that the processing of the samples with laser radiation leads to substantial changes in the dielectric constant and tangent of dielectric loss angle.
11
Bryksin, V. V., A. V. Goltsev And, and S. D. Khanin. "Relation between the tangent of the angle of dielectric losses and low drift mobility in dielectrics." Philosophical Magazine B 64, no. 1 (1991): 91–99. http://dx.doi.org/10.1080/13642819108207605.
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Cai, Longzhu. "UGCPW Structure-Based Embedded Resonator with High Quality Factor for Microwave Substrate Characterization." Electronics 10, no. 2 (2021): 113. http://dx.doi.org/10.3390/electronics10020113.
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In this paper, an ungrounded coplanar waveguide-based embedded resonator method for microwave substrate characterization was presented. The effective dielectric constant of the structure and the dielectric constant of microwave substrates can be calculated by the measured resonant frequency. The measured insertion losses at resonant frequencies and the 3 dB bandwidth can be used to determine the loaded and unloaded quality factors, including the dielectric quality factor which is related to dielectric loss tangent. The radiation loss and the extra length due to fringing effect caused by the open-end structure were taken into account to improve the extraction accuracy. The experimental unloaded quality factor of the proposed resonator at resonance order 1 reaches 211.3. The extracted dielectric constant and dielectric loss tangent of Taconic TLY at resonance order 1 are, respectively, 2.218 and 9.286×10−4, which are only 0.018 (relatively 0.82%) and 0.286×10−4 (relatively 3.18%) deviations from the datasheet values, respectively. The proposed resonator method is especially suitable for dielectric characterization of newly developed materials with the difficulty of realizing metal via holes, in which case substrate-integrated-waveguide (SIW) resonator methods are not applicable. When comparing with microstrip resonator methods, the proposed method is of higher quality factor, and it is more reliable and economical as well.
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Cai, Longzhu. "UGCPW Structure-Based Embedded Resonator with High Quality Factor for Microwave Substrate Characterization." Electronics 10, no. 2 (2021): 113. http://dx.doi.org/10.3390/electronics10020113.
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In this paper, an ungrounded coplanar waveguide-based embedded resonator method for microwave substrate characterization was presented. The effective dielectric constant of the structure and the dielectric constant of microwave substrates can be calculated by the measured resonant frequency. The measured insertion losses at resonant frequencies and the 3 dB bandwidth can be used to determine the loaded and unloaded quality factors, including the dielectric quality factor which is related to dielectric loss tangent. The radiation loss and the extra length due to fringing effect caused by the open-end structure were taken into account to improve the extraction accuracy. The experimental unloaded quality factor of the proposed resonator at resonance order 1 reaches 211.3. The extracted dielectric constant and dielectric loss tangent of Taconic TLY at resonance order 1 are, respectively, 2.218 and 9.286×10−4, which are only 0.018 (relatively 0.82%) and 0.286×10−4 (relatively 3.18%) deviations from the datasheet values, respectively. The proposed resonator method is especially suitable for dielectric characterization of newly developed materials with the difficulty of realizing metal via holes, in which case substrate-integrated-waveguide (SIW) resonator methods are not applicable. When comparing with microstrip resonator methods, the proposed method is of higher quality factor, and it is more reliable and economical as well.
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Sheveleva, M. G., L. V. Taranova, and S. G. Agaev. "Investigating the low-temperature properties of oil by the method of dielectric spectroscopy." Oil and Gas Studies, no. 3 (June 27, 2022): 96–109. http://dx.doi.org/10.31660/0445-0108-2022-3-96-109.
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The article is devoted to the possibility of using the dielectric spectroscopy method for assessing the low-temperature properties of oil. For 25 samples of oil in the fields of Tyumen region the physical and chemical characteristics have been determined, in the temperature range dielectric permittivity ℇ and the tangent angle of dielectric losses tg δ were obtained. The dielectric relaxation of oil was established. The calculated values of dielectric relaxation parameters made it possible to interpret this process as a glass transition process. The glass transition temperature tС and the region of structural solidification ∆t of oil have been determined. The dependences of tС and ∆t of oil on its physico-chemical characteristics have been established and investigated by methods of correlation and regression analysis. The glass transition temperature tС and the temperature range of structural solidification ∆t have been proposed to estimate the lowtemperature properties of oil. In the future, on the basis of data obtained, recommendations for application of dielectric spectroscopy method for forecasting and operational control of some (individual) characteristics of oil in the processes of its production, collection, preparation and transportation can be developed.
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Kalytka, V. A., A. D. Mekhtiev, P. Sh Madi, and A. V. Bashirov. "Quantum-mechanical model of dielectric losses in nanometer layers of solid dielectrics with hydrogen bonds at ultra-low temperatures." Journal of Physics: Conference Series 2140, no. 1 (2021): 012028. http://dx.doi.org/10.1088/1742-6596/2140/1/012028.
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Abstract Upon based the finite difference methods construct the solutions for Liouville quantum kinetic equation linearized by the external field, in complex with the stationary Schrodinger equation and the Poisson operator equation, for an ensemble of non-interacting hydrogen ions (protons) migrating in the field of a crystal lattice perturbed by a variable polarizing field. The influence of the phonon subsystem is not taken into account. The equilibrium (non-balanced) proton density matrix is calculated using quantum Boltzmann statistics. The temperature spectra of dielectric losses tangent angle for hydrogen bonded crystals (HBC) in a wide temperature range (50–550 K) are calculated. At the theoretical level detected the effects of nano-crystalline states (1–10 nm) during the polarization of HBC in the region of ultra-low temperatures (4–25 K).
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Bezprozvannych, G. V., Y. S. Moskvitin, I. O. Kostiukov, and O. M. Grechko. "Dielectric parameters of phase and belt paper impregnated insulation of power cables." Electrical Engineering & Electromechanics, no. 2 (March 2, 2025): 69–78. https://doi.org/10.20998/2074-272x.2025.2.09.
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Introduction. Medium voltage power cables with paper impregnated insulation remain an important component of power networks. The reliability and efficiency of such cables have been confirmed by their long service life also at nuclear power plants. Problem. It is not possible to directly determine the dielectric parameters of phase and belt paper insulation of power cables. Effective electrical diagnostic systems are required to assess the technical condition of such types of power cable insulation. The aim of the work is to substantiate the methodology for determining the dielectric properties of phase and belt paper impregnated insulation based on cumulative measurements of the electrical capacitance and the tangent of the dielectric loss angle of power cables of nuclear power plants and power networks. Methodology. The developed methodology is based on the solution of a system of linear algebraic equations of the sixth order for determining the dielectric properties of types of paper impregnated insulation of power three-core cables in a metal sheath. Scientific novelty. The differences in the structure of the probing electric field in phase and belt paper insulation depending on the inspection scheme of three-core power cables with sector cores in a metal sheath have been established. The shares of electric energy in the types of insulation under different probing electric field schemes have been determined, which allows determining the tangent of the dielectric loss angle of phase and belt paper insulation. Practical significance. The results of the practical implementation of the developed methodology for assessing the differences in the properties of phase and belt insulation of power cables of nuclear power plants and power network cables during spatial scanning of electrical insulation by frequency and voltage, respectively, are presented. References 41, figures 4, table 6.
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Zubkov, Sergei V., Ivan A. Parinov, and Alexander V. Nazarenko. "New Piezoceramic SrBi2Nb2-2xWxSnxO9: Crystal Structure, Microstructure and Dielectric Properties." Materials 17, no. 18 (2024): 4455. http://dx.doi.org/10.3390/ma17184455.
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By using the method of high-temperature solid-phase reaction, the new piezoceramic SrBi2Nb2-2xWxSnxO9 was obtained, where partial substitution of niobium (Nb) atoms with Sn4+ and W6+ atoms in the compound SrBi2Nb2O9 occurred in the octahedra of the perovskite layer (B-position). X-ray diffraction investigations showed that these compounds are single-phase SrBi2Nb2-2xWxSnxO9 (x = 0.1, 0.2) and two-phase SrBi2Nb2-2xWxSnxO9 (x = 0.3, 0.4), but all of them had the structure of Aurivillius-Smolensky phases (ASPs) with close parameters of orthorhombic unit cells. It corresponded to the space group A21am. The temperature dependences of the relative permittivity ε/ε0 and the tangent of the dielectric loss angle tan d were defined at various frequencies. It was found that doping SrBi2Nb2-2xWxSnxO9 (x = 0.1) improved the electrophysical properties of the compound: losses decreased, and the relative permittivity increased. This result was obtained for the first time. Moreover, a new result was obtained that indicated an improvement in the electrophysical properties of SrBi2Nb2O9 using the chemical element Sn (tin). This refutes the previously existing opinion about the impossibility to use Sn as a doping element.
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MEHRABOVA, Matanat, Kamal GULMAMMEDOV, and Sevinj SAFAROVA. "PHASE ANALYSIS AND ELECTRICAL PROPERTIES OF COMPOSITES BASED ON HIGH PRESSURE POLYETHYLENE WITH Na+-MONTMORILLONITE FILLER." Machine Science Journal 4, no. 2 (2024): 77–83. https://doi.org/10.61413/gmgo5334.
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One of the promising areas in polymer science is the development of methods for obtaining and studying polymer composites and nanocomposites. An important advantage of composites is their higher functionality and electrical stability compared to polymer analogues. The functioning of composite structures as an active element is associated, in particular, with charge formation phenomena. Therefore, in the development of new dielectric composites, researcher’s attention mainly focuses on their production and study of dielectric properties under effect of various factors (temperature, frequency). These studies can serve as a basis for selecting components of compositions for obtaining elements with predetermined parameters and assessing the possibility of their use as a dielectric. Analysis of literature data shows that fillers impart increased thermal and electrical conductivity, new magnetic properties to polymer materials, improve mechanical and electrical strength, etc. In the work presented the results of a study of surface microrelief and X-ray phase analysis of high pressure polyethylene with Na+ -montmorillonite filler (HPPE+x wt% Nа+ -MMT) composites, the results of the study on the temperature dependences of dielectric permittivity and the tangent of the dielectric loss angle. It was found that with an increase in the filler content, the degree of crystallinity of the composites decreases, dielectric permittivity increases, and dielectric losses decrease. The results of the X-ray phase analysis of the composites show that with an increase in the filler content of Na+MMT, the degree of crystallinity of the composites decreases from 50.5% (for 10 wt.%) to 62.1% (for 5 wt.%).
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Burdovitsin, V. A., A. V. Tyunkov, Y. G. Yushkov, and D. B. Zolotukhin. "Two-stage PVD method for protective coating formation." Journal of Physics: Conference Series 2064, no. 1 (2021): 012074. http://dx.doi.org/10.1088/1742-6596/2064/1/012074.
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Abstract The CVD methods are typically used for the formation of aluminum oxide coatings since aluminum oxide is a dielectric. The adhesion between the protective coating and the substrate material is normally improved by growing thin intermediate layers based on titanium oxides and nitrides. These intermediate layers are mainly formed using the PVD methods. In this paper, we propose a two-stage PVD method for forming a layered structure on the titanium substrate. The formation of intermediate layers was carried out by the magnetron method (first stage), and the main protective layer was deposited at the second stage using a fore-vacuum electron source. The dense beam plasma generated during the electron beam transport in a fore-vacuum gas medium compensates for the negative electrical charge accumulating on the surface of the aluminum oxide target and facilitates its effective evaporation. The electrical properties of the intermediate layers and the resulting layered coatings have been investigated, including the tangent of dielectric loss angle, the real and imaginary parts of the conductivity and the dielectric constant dependencies on frequency.
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Lavrov, I. V., V. V. Bardushkin, V. B. Yakovlev, and A. V. Bardushkin. "Simulation of dielectric characteristics of syntactic materials." Proceedings of Universities. Electronics 27, no. 1 (2022): 7–18. http://dx.doi.org/10.24151/1561-5405-2022-27-1-7-18.
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Syntactic materials (spheroplastics) having low density due to structural features, depending on the material of the microsphere walls can have a sufficiently high strength and low thermal conductivity, which makes them promising for use as heat insulation materials. By selecting the material of the microsphere walls and the concentration of the components of the spheroplastics, their dielectric characteristics can be significantly changed. In this work, the task of modeling the effective dielectric characteristics of a syntactic material with a polymer binder and filler in the form of hollow glass microspheres is considered, taking into account the presence of technological impurities in the material. A model for calculating the effective permittivity of a sample of a syntactic material was proposed, based on a model of a matrix composite with several types of inhomogeneous or homogeneous inclusions. To calculate, a generalized effective-field approximation for a heterogeneous medium with coated inclusions was used. Model calculations were carried out for syntactic foam with an organosilicon binder polydime-thylsiloxane and hollow microspheres with E-glass shell with some moisture presence in the material. Frequency dielectric characteristics of this material were obtained in the range of 102–1010 Hz. It has been shown that an increase in the volume fraction of hollow microspheres leads to a decrease in the dielectric constant and the tangent of the dielectric loss angle. It has also been shown that the calculated values are in satisfactory accordance with the experimental data obtained at an electromagnetic field frequency of 9.8 GHz.
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Shao, Yan, and Mingjie Zhang. "A Design Methodology for Low-Loss Interconnects Featuring Air Cavities and Periodically Nonuniform Widths." Applied Sciences 15, no. 5 (2025): 2799. https://doi.org/10.3390/app15052799.
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Power consumption in interconnects is a critical constraint on performance improvements in integrated circuits. This paper proposes a novel design methodology to minimize loss in interconnects and address this limitation. The approach incorporates air cavities within the substrate to lower the equivalent loss tangent, thereby reducing dielectric losses. Additionally, the inner conductor is engineered with a periodically nonuniform width to maintain stable effective characteristic impedance. To validate the effectiveness of the methodology, it is applied to both a substrate integrated coaxial line (SICL) and a stripline. Simulation results reveal a 9.76% reduction in loss for the SICL and a 19.40% reduction in loss for the stripline, demonstrating significant improvements with wide tolerance. Furthermore, this design methodology can be generalized to other interconnect types, offering the potential for additional power savings.
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Pavlov, A. V., A. M. Zhilkashinova, S. S. Gert, N. M. Magazov, Zh S. Turar, and A. B. Nabioldina. "Study of electrophysical properties of beryllium ceramics with the addition of microand nanoparticles of titanium dioxide." Bulletin of the Karaganda University. "Physics" Series 110, no. 2 (2023): 6–16. http://dx.doi.org/10.31489/2023ph2/6-16.
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In the present paper the research results of influence of nanoparticles TiO2 additions in the range 0,1 — 2,0 wt. % on electrophysical properties of oxide-beryllium ceramics (BeO + TiO2) made of micropowders are presented. The electrophysical characteristics of synthesized ceramics modified with 30 wt. % TiO2 microand nanoparticles in the electric current frequency range of 100 Hz — 100 MHz were studied by the total complex resistance method (impedance). It is known that the introduction of TiO2 addition to the BeOceramics after heat treatment in a reducing atmosphere is accompanied by a significant increase in electrical conductivity and the ability to absorb electromagnetic radiation in a wide range of frequencies. According to the results of the studies it was found that the addition of nanoparticles TiO2 into the (BeO + TiO2)-ceramics significantly reduces its static electrical resistance in comparison with the serial sample, and the specific conductivity of such ceramics significantly increases at high frequencies ~ 107 Hz. The addition of TiO2 nanoparticles significantly increases the dielectric losses of the sample sintered in the temperature range 1530 — 1550 °C. The values of real and imaginary parts of dielectric permittivity of such ceramics and the tangent of the angle of dielectric loss are two times higher compared to the serial sample — BT-30 (B — beryllium, T — titanium). The obtained results are unique in their kind, due to the experiment with a rare and strategically important material — beryllium oxide and the possibility of synthesizing new nanostructures based on it.
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Zagaynova, Alexandra, and Galina Serdyukova. "Modelling of changes in the internal insulation parameters of high-voltage bushing to analyze the reliability of control under operating voltage." Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency, no. 1 (4) (July 2, 2022): 23–27. http://dx.doi.org/10.20998/2224-0349.2022.01.12.
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The article considers the modelling of changes in the parameters of the internal insulation of high-voltage bushings for the analysis of the reliability of control under operating voltage. The data of the actually installed input at the substation were used to model the parameters of the internal insulation of the high-voltage input. To assess the relationship between the dielectric losses of the capacitor-type input insulation and its condition, a substitution scheme was used, in which the active power is equal to the power dissipated in the input insulation, and the current is shifted relative to the voltage by the same angle as in this input. The modelled parameters are the capacity of the internal insulation of the input, the active resistance of the input and the resistance that simulates a change in the parameters of the internal insulation. The numerical value of the capacitive current through the insulation of the high-voltage input, the numerical value of the active current, the numerical value of the resistance, and the numerical value of the power loss for this input are calculated. A simplified high-voltage input insulation scheme has been developed. Losses were calculated and evaluated when the tangent of the dielectric loss angle was changed by 2%. The replacement scheme for isolating the high-voltage input without taking into account the possibility of changing the parameters is given. A model was built that allows you to take into account the change in input parameters, to which an additional resistance is connected in parallel. A resistive divider circuit was chosen as the circuit simulating the parameters because it provides sufficient accuracy, stability, and power. The method that was used to simulate the change in the parameters of the internal insulation of the capacitor-type high-voltage inputs can be recommended as an aid to the analysis of the sensitivity of the control device under the operating voltage of the inputs of power transformers.
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Gainullina, Leysan. "Effect of Individual Sulfide on the Stability against Oxidation of Transformer Oil and Its Electrical Parameters." Problems of the Regional Energetics, no. 4(52) (November 2021): 23–30. http://dx.doi.org/10.52254/1857-0070.2021.4-52.03.
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This study is devoted to the improvement of the transformer oil quality, using a new inhibiting additive, since the extensively used inhibitory additive ionol is sensitive to organosulfur compounds of sulfur oils. From the earlier works, the organosulfur compounds are known to affect ambiguously the transformer oils characteristics. Therefore, it was of interest to study the individual sulfides as the inhibitory additives. The goal was achieved by the researches with the use of the model mixtures consisting of the selectively purified transformer oil (free from ionol) along with the individual sulfides, decylcyclohexylsulfide and decylfenylsulfide, at concentration of 0.5 %, Their effect on stability against oxidation of the selectively purified oil, on its electric strength and tangent of the dielectric losses’ angle was studied. The primary results obtained were, firstly, the rate slowing down of water formation in oil and of water-soluble acids formation in oil upon its oxidation in the presence of the individual sulfides, and, secondly, an increase in the electric strength and decrease in the dielectric losses compared to the transformer oil, containing ionol. It was established that decylcyclohexylsulfide inhibitory properties are stronger compared to those of decylfenylsulfide, which was testified by less quantities (by 1.8 times) of the water formed and of water-soluble acids (by 2.22 times). The introduction to oil of 0.5 % decylcyclohexylsulfide and decylfenylsulfide increased the oil electric strength, correspondingly, by 2.6 and by 5.5 times, upon water concentration in oil equal to 15·10-2 g/kg. The significance of the results obtained is in improving the transformer oil quality produced from the sulfur oils with the use of a novel additive.
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Kalytka, Valery, Alexander Aliferov, Mikhail Korovkin, Ali Mehtiyev, and Perizat Madi. "Quantum properties of dielectric losses in nanometer layers of solid dielectrics at ultra-low temperatures." Proceedings of the Russian higher school Academy of sciences, no. 2 (July 21, 2021): 14–33. http://dx.doi.org/10.17212/1727-2769-2021-2-14-33.
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Using the methods of quasi-classical kinetic theory, continuum electrodynamics, and non-relativistic quantum theory, we construct and study the quantum kinetic equation of proton relaxation, which, together with the Poisson operator equation describes the mechanism of diffusion tunneling transport of hydrogen ions (protons) in the potential field of a crystal lattice perturbed by a polarizing field (quantum diffusion polarization) in crystals with hydrogen bonds. Using the apparatus of the density matrix (statistical matrix), by complete quantum-mechanical averaging of the polarization operator, studies are carried out of the experimental value of the polarization of the dielectric, as a function of the parameters of the external electric field (amplitude, frequency of electromotive force) and temperature. When calculating the equilibrium density matrix for an ensemble of basic relaxers (hydrogen ions), the proton-proton and proton-phonon interactions are not taken into account, and the Hamilton operator for the phonon subsystem is assumed to be a numerical constant for a given crystal under given experimental conditions (calculated by computer method as a parameter for comparing the theory with the experiment). The influence of the phonon subsystem on the kinetics of the relaxation process is reduced to a weak spatially homogeneous force field acting on protons moving in the field of the main forces of hydrogen bonds. The Hamilton of the proton subsystem is constructed for the model of an ideal proton gas in equilibrium with the ionic subsystem of the crystal lattice, and the equilibrium statistical operator of the proton subsystem is written using the Boltzmann quantum statistics. Theoretically, the size effects are found to be manifested in shifts of the low-temperature (50–100 K) maxima of the dielectric loss angle tangent towards ultra-low temperatures (4–25 K) with a decrease in the amplitudes of the maxima by 3-4 orders of magnitude, with a reduction in the thickness of the crystal layer from 1–10 microns to 1–10 nm. The effect of anomalous displacements of low-temperature maxima, which is explained by the abnormally high quantum transparency of the potential barrier for protons (0.8-0.9) in thin films of a crystal with hydrogen bonds (1-10 nm), causes, near the temperatures of the shifted maxima of dielectric losses (4–25 K), a quasi-ferroelectric state, which is also characterized by abnormally high values of the real component of the complete dielectric permittivity (2.5–3.5millions).
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Kharalgin, S. V., and M. I. Voytovich. "Investigation of the dielectric characteristics of materials manufactured using additive technologies." Russian Technological Journal 9, no. 2 (2021): 57–65. http://dx.doi.org/10.32362/2500-316x-2021-9-2-57-65.
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Based on the existing methods of measuring the dielectric characteristics of materials, the most optimal method for performing calculations in the electrodynamic computer-aided design system is selected by the finite integration method. Based on the calculated values of the scattering matrix, the permittivity and the tangent of the dielectric loss angle of the printed polymer samples are calculated according to a given algorithm. When evaluating the accuracy of the calculation of the dielectric characteristics, validation was performed for a sample with the specified characteristics. For a sample printed using the technology of fused filament fabrication, the influence of the filling parameters on the dielectric characteristics of the printed model in the X-band of wavelengths was estimated. The description of the model implemented in the computer-aided design system is given. By processing the simulation results, approximating dependences for the permittivity and losses on the degree of filling with the dielectric are obtained. It follows from the calculated angular diagrams that the decrease in the degree of filling of the dielectric directly affects the degree of anisotropy of the polymer obtained during printing in the plane of the extruded layers. This also increases the depth of the extremes observed at angles of 0°, 90° and 180°. The presence of these extremes is directly related to the fact that the force lines of the main wave type in the waveguide are located perpendicular to the wide wall and in a situation where the volumes of air gaps between the cylinders are parallel to the force lines of tension, there is a general decrease in the dielectric constant. For a printed sample consisting of two layers of crossed cylinders, the air volumes are parallel to the lines of force with a period of ninety degrees, which is confirmed by the results obtained. An increase in the depth of the extremes with a decrease in the degree of filling is associated with a corresponding increase in the air space between the cylinders in the layer of the printed polymer.
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Yurasov, Yu I., and A. V. Nazarenko. "Parameter of dielectric loss distribution in the new model for complex conductivity based on Havriliak–Negami formula." Journal of Advanced Dielectrics 10, no. 01n02 (2020): 2060006. http://dx.doi.org/10.1142/s2010135x20600061.
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This paper is focused on the comparison of the results of various approximation models describing the frequency dependences of the dielectric constant [Formula: see text] and [Formula: see text], the tangent of the loss angle tg[Formula: see text] and the electrical conductivity [Formula: see text] and [Formula: see text] of nonlinear dielectrics. The classic ferroelectric material of the PZT system with [Formula: see text] was chosen as the object of study. Based on the analysis of temperature-frequency dependences of the “empirical” parameters [Formula: see text] and [Formula: see text], a regularity has been revealed that allows them to be calculated. A new relationship has been established through the parameter [Formula: see text], which allows to relate the temperature and frequency dependences of the complex electrical conductivity as [Formula: see text] and as [Formula: see text] in the Havriliak–Negami approximation models and in the new model for the description of the complex electrical conductivity [Formula: see text]. It is shown that [Formula: see text] is a parameter of the temperature-frequency distribution of dielectric losses. Using the obtained expressions, a new theoretical description of experimental spectra having a relaxation character was proposed. It has been proven that the use of the new model makes it possible to accurately describe the set of studied spectra, including the high and low frequencies, in the frequency range from [Formula: see text] to 108[Formula: see text]Hz.
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Mikheev, D. A., Ye A. Danilov, O. A. Savitsky, et al. "Polymeric-comcomposite piezofilms for active elements of sound-transparent conformal sonar arrays." Transactions of the Krylov State Research Centre S-I, no. 2 (2021): 17–26. http://dx.doi.org/10.24937/2542-2324-2021-2-s-i-17-26.
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This paper describes manufacturing technology and main dielectric and electrophysical properties of a new polymeric composite piezomaterial, highlighting its advantages over conventional piezoceramics. The study also suggests a manufacturing technology for active elements of a long conformal emitter/receiver array. Polymeric composite piezomaterial discussed in this paper was based on polyvinyldenfluoride (PVDF) and piezoceramics of lead zirconate-titanate system (CTS). Its main properties given in this study are: frequency curves for dielectric (tangent of dielectric loss angle, relative dielectric constant, quality factor) ane electromechanic (tension piezomodulus, acoustic impedance) properties. Performance parameters of the active element given in this paper are: directional patterns at different frequencies, effective piezomodulus and frequency-piezosensitivity curve. The paper shows that this composite material is equal to conventional PVDF films in terms of its dielectric properties and compliance but offers better electromechanical parameters. Piezoconverter designs suggested in this study feature uniform frequencysensitivity diagram for both transmission and reception over the whole frequency band under investigation, as well as insensitivity to flow noise. New composite materials newly introduced to hydroacoustics also make these designs of receiving array elements insensitive to parasytic vibration of hull structures. The paper shows the advantages of the developed composite piezofilm as compared to conventional hydroacoustic piezoceramics. Piezofilms, including composite ones, are as sensitive as ceramics but more compact, less heavy and feature much greater specific area of reception. A promising approach would be to further increase piezomoduli of film-based materials keeping their acoustic impedance low, which would result in greater operational efficiency of receiving sonar arrays.
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Igor, Nazarenko, Didenko Oleksandr, Loboda Aleksandr, Kushlyk Ruslan, and Chervinsky Leonid. "ELECTRICAL PROPERTIES OF "WATER IN CASTOR OIL" EMULSION." Eastern-European Journal of Enterprise Technologies 4, no. 6 (106) (2020): 38–44. https://doi.org/10.15587/1729-4061.2020.210312.
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The results of the research into the electrical properties of the "water in castor oil" emulsion, which make it possible to substantiate the technology of castor oil purification from plant impurities and water in an electric field, were presented. The experimental studies of the electrical properties of the "water in castor oil" emulsion revealed the dependences of specific resistance to direct and alternating currents and dielectric loss angle tangent on the temperature and water content. It was proved that the active component of specific resistance to the suspension "water in castor oil" on AC is smaller than resistance to DC. That is why, at the temperature of 80 °C and water content of 2 %, heat release on AC is 10 % higher than the heat release on DC. According to this, it is advisable to perform the process of castor oil purification from plant impurities and water residues on AC. This makes it possible to obtain additional heat release and thereby compensate for heat losses for the vaporization of flotation bubbles, which leads to the stable process of flotation purification. A comparison of the magnitudes of polarization losses and losses of end-to-end electrical conductivity for pure oil indicates their identical order. The addition of water leads to an increase in polarization losses due to the structural and dipole polarization of water as a polar fluid. Due to this, from the theoretical point of view, it can be argued about additional local heat release on finely dispersed water drops in the quantity, which can ensure the compensation for the heat needed for vaporization. According to this, vaporization does not require indirect heating of the electrode area from an external source at the expense of thermal conductivity. The obtained results of the experimental research make it possible to substantiate the technological and structural parameters of the electro-technological complex of castor oil purification in the electric field of the cylindrical system of electrodes
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Tan, Weixian, Yadong Wang, Pingping Huang, et al. "A Method for Predicting Landslides Based on Micro-Deformation Monitoring Radar Data." Remote Sensing 15, no. 3 (2023): 826. http://dx.doi.org/10.3390/rs15030826.
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Mine slope landslides seriously threaten the safety of people’s lives and property in mining areas. Landslide prediction is an effective way to reduce losses due to such disasters. In recent years, micro-deformation monitoring radar has been widely used in mine slope landslide monitoring. However, traditional landslide prediction methods are not able to make full use of the diversified monitoring data from these radars. This paper proposes a landslide time prediction method based on the time series monitoring data of micro-deformation monitoring radar. Specifically, deformation displacement, coherence and deformation volume, and the parametric degree of deformation (DOD) are calculated and combined with the use of the tangent angle method. Finally, the effectiveness of the method is verified by using measured data of a landslide in a mining area. The experimental results show that our proposed method can be used to identify the characteristics of an imminent sliding slope and landslide in advance, providing monitoring personnel with more reliable landslide prediction results.
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Yusuf, Muhammad A., and Mutari Hajara Ali. "DESIGN AND SIMULATION OF A HIGH-GAIN DUAL-BAND MICROSTRIP PATCH ANTENNA ARRAY FOR 26/28 GHz 5G APPLICATIONS." FUDMA JOURNAL OF SCIENCES 9, no. 3 (2025): 1–6. https://doi.org/10.33003/fjs-2025-0903-2653.
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This paper presents a high-gain dual-band microstrip patch antenna array design and simulation for 26/28 GHz 5G applications. The 26 and 28 GHz bands are particularly notable among the existing bands for millimeter-wave applications due to their wide bandwidth and lower absorption rates. The antenna is developed in the CST simulation environment on a Rogers RT5880 substrate with a thickness of 0.508 mm, a relative dielectric permittivity of 2.2, and a loss tangent of 0.0009. The Rogers RT substrate is chosen for its low dielectric loss, controlled dielectric constant, environmental stability, ease of fabrication, and high reliability, making it ideal for high-frequency and high-performance applications. The transmission line model method is used to calculate the antenna dimensions designed to resonate at 26/28 GHz. To achieve high gain and wide bandwidth, arraying and slotting techniques are applied to rectangular patch antennas, as these methods significantly enhance gain, bandwidth, directivity, and radiation pattern control, making them suitable for advanced communication applications. The proposed 1×2 patch antenna array, with dimensions of 33.4 × 21.6 × 0.508 mm³, is designed using a tapered feedline. The antenna array resonates at 26.27 GHz and 28.0 GHz, achieving return losses of -16.55 dB and -31.78 dB, bandwidths of 0.58 GHz and 1.54 GHz, VSWR values of 1.35 and 1.05, gains of 9.12 dB and 12.43 dB, and directivities of 9.77 dBi and 13.05 dBi, respectively. The antenna exhibits higher gain and directivity compared to existing array designs in the literature. This cost-effective and compact antenna array is...
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Bogachkov, I. V. "Determination of Electromagnetic Parameters of Liquid Substances in the Microwave Range." T-Comm 18, no. 6 (2024): 55–60. https://doi.org/10.36724/2072-8735-2024-18-6-55-60.
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The experimental researches of the electrodynamic properties of liquids in the microwave range is described in this work. The calculation formulas within the framework of a single-wave model and the results of trial experiments are presented. Currently, the study of the use of electromagnetic waves in the microwave range (from 0.3 GHz to 30 GHz – UHF (ultra-high frequencies) and SHF (super-high frequencies)) for heating various substances with suitable electrodynamic properties is continuing. Liquid substances are of particular interest in this field. Microwave radiation treatment can be used to solve the problems of disinfection of water, milk, and so on. Microwave heating can be used in the oil industry. An experimental measuring device was assembled to determine the electrodynamic properties of liquid substances. To measure the electrodynamic parameters of substances, a hollow segment of a coaxial line was constructed, which has a disassembly structure and can be completely filled with the test substance before measurements. The dimensions of the coaxial segment are chosen so that, in the absence of filling, its characteristic resistance (impedance) would be 50 ohms, which corresponds to the characteristic resistance (impedance) of the connecting segments of the coaxial lines, and at the same time higher types of waves would be absent in the transmission line. After calibration the measuring object was connected to the system. The frequency characteristics of the VSWR (voltage standing wave ratio) and attenuation were measured using a measuring system. In the absence of filling, the segment is coordinated with the cables of the measuring system, therefore, the reflected wave will be practical ly absent, and the signal attenuation will be determined by losses in the conductors and contact connections of the segment. When filling the line segment with the liquid substance under testing, both the VSWR and the attenuation will change. From this information, it is possible to determine the electrodynamic characteristics of the filling: the tangent of the dielectric loss angle and the complex relative permittivity. To obtain quantitative characteristics, it is convenient to use the D-matrix Keywords: microwave heating, liquid dielectric media, reflection factor, loss coefficient, microwave range, method of D-matrixes method. A scheme of the measuring installation, devices and their connections for experimental research is presented. In the range from 2 GHz to 18 GHz, experimental studies of two segments in waveguide and coaxial designs without filling with dielectrics, as well as with water filling, were carried out. The paper presents the frequency dependences of VSWR, reflection coefficient, attenuation averaged for two-line segments without filling. These data allow us to identify the systematic error of the experiment, which will allow us to correct the result for the filled segment. The analysis shows that in the unfilled segment, losses in contact connections prevail over losses in conductors. The frequency dependences of the reflection coefficient, the relative absorption power in the dielectric and the tangent of the dielectric loss angle for the experiment with water are presented. The results obtained are consistent with those published. Thus, using the considered technique, it is possible to determine the electromagnetic parameters of various liquid substances in the microwave range. Currently, the study of the use of electromagnetic waves in the microwave range (UHF (ultra-high frequencies) – 0.3-3 GHz, SHF (super-high frequencies) – 3-30 GHz) for heating various substances with suitable electro dynamic properties is continuing. Liquid substances are of particular interest in this field. Microwave radiation treatment can be used to solve the problems of disinfection of water, milk, and so on. Microwave heating can be used in the oil industry (reducing the viscosity of oily materials when pumping through pipes, melting asphalt paraffin plugs and polluting deposits in the pipes of oil wells, and so on). Most often, to determine the electrodynamic parameters of sub stances, a method of measuring characteristics is used when the sub stances under study are located inside a volumetric resonator. Despite the good accuracy, the disadvantage of this approach is obvious - it is impossible to adjust the measurement frequency parameters in a sufficiently wide operating range during experimental studies.
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Bonnefoy, Léa E., Antoine Lucas, Alexander G. Hayes, et al. "Composition, Roughness, and Topography from Radar Backscatter at Selk Crater, the Dragonfly Landing Site." Planetary Science Journal 3, no. 8 (2022): 201. http://dx.doi.org/10.3847/psj/ac8428.
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Abstract The Selk crater region is the future landing site of NASA’s Dragonfly mission to Titan. The region was imaged by the Cassini RADAR at incidence angles from 5° to 72° and at various polarization angles. Using this data set, we mapped six terrain units and assembled a backscatter curve for each, providing normalized backscatter cross section (σ 0) as a function of incidence angle. By fitting these backscatter curves with a sum of a quasi-specular and diffuse terms and evaluating three alternative formulations of the first and two for the second, we extracted the best-fit surface effective dielectric constant, rms slope, and scattering albedo. Although the parameters’ absolute values are model dependent, relative values between terrains indicate real variations in surface properties. The results are consistent with the impact exposing and fracturing a low-loss tangent material such as the water-ice bedrock, which is likely also present in the hummocky terrains and to a lesser degree in the plains and interdune regions. The dunes and dark terrains are composed of smooth, uniform material with low dielectric constant (1.5–2.3 median values for all models) compatible with organic sand. A diffuse single-scattering model enabled independent derivation of the dielectric constant from high-incidence observations, leading to low values (<2) over all terrains, indicating a depolarizing (sub)surface. Finally, radarclinometry revealed lateral variations in rim height, which remains below 300 m along the SARTopo profile but reaches up to 600 m at other locations, hinting at a rim less eroded than previously thought.
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Yang, Shasha, Anjie Jin, Wen Nie, Cong Liu, and Yu Li. "Research on SSA-LSTM-Based Slope Monitoring and Early Warning Model." Sustainability 14, no. 16 (2022): 10246. http://dx.doi.org/10.3390/su141610246.
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For geological disasters such as landslides, active prevention and early avoidance are the main measures to avoid major losses. Therefore, landslide early warning is an effective means to prevent the occurrence of landslide disasters. In this paper, based on geological survey and monitoring data, a landslide monitoring and early warning model based on SSA-LSTM is established for the landslide in Yaoshan Village, Xiping Town, Anxi County, Fujian Province, China. In the early warning model, the hyper parameters of the LSTM neural network are optimized using the SSA algorithm in order to achieve high-accuracy displacement prediction of the LSTM displacement prediction model, and are compared with the unoptimized LSTM, and the results show that the prediction effect of the optimized SSA-LSTM model is significantly improved. Since landslide monitoring and early warning is a long-term work, the model trained by the traditional offline learning method will inevitably have distortion of the prediction effect as the monitoring time becomes longer, so the online migration learning method is used to update the displacement prediction model and combine with the tangent angle model to quantify the warning level. The monitoring and early warning model put forth in this research can be used as a guide for landslide disaster early warning.
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Jetti, Chandrasekhar Rao, Tathababu Addepalli, Sreenivasa Rao Devireddy, et al. "Design and Analysis of Modified U-Shaped Four Element MIMO Antenna for Dual-Band 5G Millimeter Wave Applications." Micromachines 14, no. 8 (2023): 1545. http://dx.doi.org/10.3390/mi14081545.
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A novel compact-slotted four element multiple input multiple output (MIMO) planar monopole antenna is proposed for 5G mmWave N257/N258 and N262 band applications. The antenna, with dimensions of 12 mm × 11.6 mm × 0.508 mm (1.036λo ×1.001λo×0.043λo where λo is computed at lowest cutoff frequency), is fabricated on a Rogers RT/duroid 5880 (tm) substrate with a relative permittivity of 2.2 and a dielectric loss tangent of 0.0009. The suggested antenna consists of four U-shaped radiating elements (patches) on top of the dielectric material and a slotted ground on the bottom. The radiating elements are fed by a 50-ohm microstrip line feed. To improve the impedance performance of the MIMO antenna, a rectangular strip of 1.3 mm × 0.2 mm and a couple of rectangular slots are added to each radiating element. The first operating band at 27.1 GHz, ranging from 25.9 GHz to 27.8 GHz, is achieved by using slotted U-shaped radiating elements. The second operating band at 48.7 GHz, ranging from 47.1 GHz to 49.9 GHz, is obtained by etching hexagonal slots on the ground. The antenna design achieves an isolation of >27 dB through the orthogonal positioning of radiating elements and slots on the ground. The designed antenna operates at 27 GHz (N257/N258) and 48.7 GHz (N262) bands, exhibiting stable radiation patterns, a peak gain of >5.95 dBi, radiation efficiency of >90%, an envelope correlation coefficient of <10−6, a total active reflection coefficient of ≤−10 dB, channel capacity losses of <0.03 bits/s/Hz, and a mean effective gain of ≤−3 dB. The simulated and measured results of the antenna show good agreement, making it well-suited for 5G mmWave communication applications.
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G.N. Mammadova. "Optical Properties of Tlinse2<Au> Single Crystals." Journal of Electrical Systems 20, no. 7s (2024): 2237–43. http://dx.doi.org/10.52783/jes.3959.
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This paper presents the results of studying the surface microrelief in 2D and 3D models and analyzing the spectroscopy of a three-junction TlInSe2<Au> crystal. Analysis of the results obtained showed that with a change in the composition of the TlInSe2<Au> crystal, sharp changes occur in the microrelief of its surface. An X-ray optical diffraction analysis of the TlInSe2<Au> crystal was experimentally carried out. Based on ellipsometric data, optical functions were determined - the real and imaginary parts of the dielectric permittivity of crystals, the coefficients of optical absorption and reflection, the dependence of energy losses and electric field power on the effective density, the spectral dependences of the real (σr) and imaginary (σi) parts, optical electrical conductivity were experimentally studied. The fluorescence spectra of the ternary compound TlInSe2<Au> were isolated and analyzed when excited by light with a wavelength of 532 nm. X-ray studies of TlInSe2<Au> showed that this phase crystallizes into tetragonal systems. Ellipsometric measurements showed that the real (ε1) and imaginary (ε2) parts of the dielectric constant are components of the dielectric constant tensor of the uniaxial joints under consideration and do not depend on the angle. Analysis of the dependence of the real and imaginary parts of the refractive index of the TlInSe2<Au> crystal on photon energy showed that the nature of the change in the real and imaginary parts of the dielectric constant does not differ significantly. When analyzing the spectral dependences of the real (σr) and imaginary (σi) parts of the optical electrical conductivity, it was noticed that the real part of the optical electrical conductivity increases exponentially in the energy range 0.894-3.505 eV. In the energy range of 0.654-2.91 eV, the imaginary part of the optical electrical conductivity increases linearly, reaches a maximum value, and decreases at an energy of 2.91 eV. At 3.6 eV, an inversion of the imaginary part of the optical electrical conductivity of the TlInSe2<Au> compound is observed. From the graphs of the effective power density versus electric field energy losses, it is known that the effective power density increases significantly in the energy range of 0.805–3.52 eV. The fluorescence spectrum of the ternary compound TlInSe2<Au> upon excitation with light with a wavelength of 532 nm has been studied and it has been established that this phase has luminescent properties.
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Kadyrakunov, K. B., V. E. Nikulin, А. K. Nurmagambetova, A. E. Aizhanova, and R. T. Nurgalieva. "Investigation of snow characteristics in the microwave range for avalanche forecasting." BULLETIN of the L.N. Gumilyov Eurasian National University. Technical Science and Technology Series 147, no. 2 (2024): 137–53. http://dx.doi.org/10.32523/2616-7263-2024-147-2-137-153.
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It should be noted that avalanches of accumulated snow masses are typically triggered by climatic factors, including abrupt weather changes (such as variations in atmospheric pressure and air humidity), precipitation, and heavy snowfall. The volume of snow in an avalanche can reach several million cubic meters. However, even avalanches with a volume of about 5 m³ can be life-threatening. To reduce and prevent these negative factors, it is necessary to predict and prevent the occurrence of avalanches at an earlier stage. This task is solved by regular monitoring of snow and weather conditions on the proposed area of mountain slopes. In order to achieve this objective, a variety of methods and techniques based on different physical and technical principles are currently used. One of the most promising directions is the use of radio waves of ultra-high frequency (UHF) range. The present study is devoted to the examination of the possibility of UHF methods for the remote measurement of snow parameters. Two experimental installations for measurement of various snow parameters in the microwave radio wave range have been constructed for avalanche forecasting. Predictors of avalanches are chosen based on physical considerations and methods of mathematical statistics. The objective of our research is to create an installation to study the characteristics of mountain snow in the avalanche-hazardous areas of the Shimbulak ski resort. The main parameters of electric snow that influence the process of transmission, propagation and reflection of radio waves are considered. As a result of the changes, the dipole moment increases, which causes the separation band of the alternating influence of water to expand and move to the low-frequency region. The results of experimental studies of radio-wave attenuation in snow used to calculate the absorption coefficient of microwave radiation in snow are presented. Dielectric permeability and tangent of the angle of snow losses have been measured using the waveguide method.
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Kalytka, Valeriy, Ali Mekhtiyev, Yelena Neshina, et al. "Quasi-Classical Models of Nonlinear Relaxation Polarization and Conductivity in Electric, Optoelectric, and Fiber Optic Elements Based on Materials with Ionic–Molecular Chemical Bonds." Applied Sciences 14, no. 24 (2024): 11830. https://doi.org/10.3390/app142411830.
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A generalized scientific review with elements of additions and clarifications has been carried out on the methods of theoretical research on the electrophysical properties of crystals with ionic–molecular chemical bonds (CIMBs). The main theoretical tools adopted are the methods of quasi-classical kinetic theory as applied to ionic subsystems relaxing in layered dielectrics (natural silicates, crystal hydrates, various types of ceramics, and perovskites) in an electric field. A universal (applicable for any CIMBs class crystals) nonlinear quasi-classical kinetic equation of theoretical and practical importance has been constructed. This equation describes, in complex with the Poisson equation, the mechanism of ion-relaxation polarization and conductivity in a wide range of polarizing field parameters (0.1–1000 MV/m) and temperatures (1–1550 K). The physical model is based on a system of non-interacting ions (due to the low concentration in the crystal) moving in a one-dimensional, spatially periodic crystalline potential field, perturbed by an external electric field. The energy spectrum of ions is assumed to be continuous. Elements of quantum mechanical theory in a quasi-classical model are used to mathematically describe the influence of tunnel transitions of hydrogen ions (protons) during the interaction of proton and anion subsystems in hydrogen-bonded crystals (HBC) on the polarization of the dielectric in the region of nitrogen (50–100 K) and helium (1–10 K) temperatures. The mathematical model is based on the solution of a system of nonlinear Fokker-Planck and Poisson equations, solved by perturbation theory methods (via expanding solutions into infinite power series in a small dimensionless parameter). Theoretical frequency and temperature spectra of the dielectric loss tangent were constructed and analyzed, the molecular parameters of relaxers were calculated, and the physical nature of the maxima of the experimental temperature spectra of dielectric losses for a number of HBC crystals was discovered. The low-temperature maximum, which is caused by the quantum tunneling of protons and is absent in the experimental spectra, was theoretically calculated and investigated. The most effective areas of scientific and technical application of the theoretical results obtained were identified. The application of the equations and recurrent formulas of the constructed model to the study of nonlinear optical effects in elements of laser technologies and nonlinear radio wave effects in elements of microwave signal control systems is of the greatest interest.
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Zaporotskova, Irina, Vladislav Kalinichenko, Lev Kozhitov, Pavel Zaporotskov, and Tatyana Kislova. "On the Influence of Carbon Nanotubes on the Physical and Mechanical Properties of Polypropylene." NBI Technologies, no. 2 (October 2021): 27–36. http://dx.doi.org/10.15688/nbit.jvolsu.2021.2.5.
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One of the most interesting and promising materials of our time is carbon nanotubes. Most applications of nanotubes are associated with the possibility of combining them with other materials in the form of alloys, mixtures, composites or hybrid materials. In particular, the idea of including carbon nanotubes as a filler in various polymer-based matrices (for example, traditional polymers such as thermoplastics, thermosetting materials or elastomers, as well as conjugated polymers) for the formation of polymer/carbon nanotube nanocomposites has revolutionized materials science and engineering. The introduction of carbon nanotubes into the composite structure affects the structure and properties of the polymer binder, as well as the composite material as a whole. Currently, there are no experimental developments on the basis of which the introduction, distribution and stabilization of the dispersion of carbon nanotubes in polymer composites would be implemented in industrial technology. The development of the most effective methods for introducing carbon nanotubes into polymer materials and determining their effect on the physical and mechanical properties of polymers is an urgent and priority task. It is possible that these methods will be able to find application in the industrial production of polymer composite materials intended for use and operation in various extreme conditions (whether it is high temperatures, erosion, high force exposure or highly acidic/highly alkaline environments). The main physical and mechanical properties of polypropylene samples saturated with carbon nanotubes taken at different concentrations (0; 0.01; 0.05 and 0.1 wt. %), who found that the addition of CNT in large quantities negatively affects the tensile and bending strength limits, which may be associated with an increase in the degree of heterogeneity of the structure and the appearance of large agglomerates, which will be points of stress concentration. With an increase in the mass fraction of carbon nanotubes in the polymer nanocomposite, the tangent of the dielectric loss angle increases, which leads to better conductivity of the sample containing a larger number of nanotubes. This may be due to the fact that nanotubes become conductors of electric current in the volume of the polymer matrix.
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Lopez-Munoz, Gerardo, Dominik Grochala, Anna Paleczek, et al. "Lithography-Free Metaplasmonic Sensors Developed by TWD/GLAD Technique." ECS Meeting Abstracts MA2024-01, no. 49 (2024): 2705. http://dx.doi.org/10.1149/ma2024-01492705mtgabs.
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Nowadays, plasmonic sensors are the most widely used and commercialized label-free optical biosensors and have become a widespread tool for studying chemical/biochemical interactions. Label-free, real-time, and direct measurements are the major benefits of the plasmonic sensors, including high-throughput surface bio-functionalization strategies without amplification or pretreatment of the sample [1]. The working principle of plasmonic sensing has been extensively described and reviewed over the decades [2], however, the possibility to develop cheap, effective, and clinically-accepted biosensors has recently become available due to the development of nanotechnology. Briefly, these nanostructures can be localized or can be arranged on 2D arrays of plasmonic metasurfaces, and can be fabricated by single-layer metallic films and a combination of metallic and dielectric films. The most popular plasmonic metals are gold and silver due to their high conductivity and low dielectric losses. Generally, top-down nanofabrication methods based on laser/e-beam lithography have been used, including nanostencil lithography based on shadow-masked nano-pattering and nanoimprint lithography [3]. Although such technologies have a high potential to achieve scalable and cost-effective nanofabrication at the wafer scale, these processes maintain the following main challenge: a master nano-mold/pattern is required to transfer metasurfaces with an associated high cost. Therefore, other technologies are the subject of research that overcomes this limitation and still offer an outstanding quality of metallic films, such as TDW (thermal dewetting) and GLAD (glancing angle deposition) (Fig.1). These techniques do not require master nano-mold/patterns; consequently, they can achieve lithography-free large-scale plasmonic metasurfaces [4]. TDW and GLAD usually generate quasi-ordered plasmonic metasurfaces compared to conventional lithographic methods. In this paper, the experimental results of the optical sensing properties of the sensors developed by the utilization of the combination of these two technologies in a single system are presented. The TWD/GLAD magnetron sputtering system has been designed and manufactured based on the Kurt J. Lesker MAG-Torus magnetrons, supplied with DC/RF power sources and an ECR manipulator that enables deposition at various angles with maximal 20 rpm rotation speed and heating option up to 850oC. The system is controlled by the software that enables deposition of the samples with the same parameters which pave the way for fabrication of the sensors on the industrial scale. The optical-sensing system was built based on an ST-VIS-50 spectrometer (Ocean Optics) and Tungsten Halogen Source (360-2000 nm, 2800 K, Ocean Optics) and optical table from Thorlabs. The obtained reflectance measurement has shown that the utilization of the GLAD technique decreases the reflectance peak in comparison with samples deposited without GLAD (flat samples). At the same time, angles in the range of 82-86oC seem to be preferable for nanostructure fabrication. Additionally, the utilization of the TWD technique, i.e. deposition at lower temperatures in the range of 60-100oC (depending on the substrate) and then annealed at higher temperatures such as 250oC and 300oC in a vacuum and under argon flow in the deposition chamber led to increased normalized response. However, the experiments have shown that the optimal annealing time is between 30-45 min depending on the SPR multi-structure, for example for Ag (6nm), Ti (2nm), and Au (2nm) the 30min at 250oC seems to be the best set. For such compositions, the surface sensitivity (nm/nm) and bulk sensitivity (nm/RIU) are more or less the same - 0.9 and 300, respectively. The obtained results are very promising for developing cheap, rapid, and very effective biosensors for various applications. Therefore, the obtained results seem to be very interesting for the ECS conference audience, for example, the developed Ag/Ti/Au multi-structures can be applied in novel organ-on-a-chip platforms for LADMET (liberations, absorption, distribution, metabolism, excretion, and toxicology) analysis [5]. Fig. 1. Schematic diagram representation of lithography free methods for developing quasi-ordered metamaterials from left to right: Thermal dewetting and glancing angle deposition. The insert shows the chiral plasmonic nanospirals fabrication by glanced angle deposition [4]. References: [1] LC Oliveira et al., Springer, 2019. ISBN: 9783030174859 [2] VG Kravets et al., Chem. Rev. 2018, 118, 12, 5912–5951. doi.org/10.1021/acs.chemrev.8b00243 [3] M. Zandieh et al., Analytical Biochemistry. 2018, 548, 96-101. doi.org/10.1016/j.ab.2018.02.023 [4] GA López-Muñoz et al., Front. Sens. 2022, 3:945525. doi: 10.3389/fsens.2022.945525 [5] J. Ramon, A. Rydosz, Human Organs-on-a-chip, 2023. ISBN: 9780443153846 The work was financially supported by the National Science Centre, Poland Sonata-BIS project no 2022/46/E/ST7/00008. Figure 1
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Pylypchuk, Oleksandr S., Serhii E. Ivanchenko, Mykola Y. Yelisieiev, et al. "Behavior of the dielectric and pyroelectric responses of ferroelectric fine‐grained ceramics." Journal of the American Ceramic Society, January 28, 2025. https://doi.org/10.1111/jace.20391.
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AbstractWe demonstrated the correlations between the specific temperature behavior of the colossal dielectric permittivity, unusual electro‐transport characteristics, and frequency dependences of the pyroelectric response of the fine‐grained ceramics prepared by the spark plasma sintering of the ferroelectric BaTiO3 nanoparticles. The temperature dependences of the electro‐resistivity indicate the frequency‐dependent transition in the electro‐transport mechanisms between the lower and higher conductivity states accompanied by the maximum in temperature dependence of the loss angle tangent. The pyroelectric thermal wave probing revealed the existence of the spatially inhomogeneous counter‐polarized ferroelectric states at the opposite surfaces of the ceramic sample. We described the temperature behavior of the colossal dielectric response and losses using the core−shell model for ceramic grains, effective medium approximation, and Maxwell−Wagner approach.
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Karpov, Artem, Maksim Kustov, Oleg Kulakov, Oleksii Basmanov, and Yuliia Mykhailovska. "Interaction of an electromagnetic wave with the surface of a real explosive substance." Problems of Emergency Situations, December 2024, 57–71. https://doi.org/10.52363/2524-0226-2024-40-5.
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To develop the theoretical basis for the effective detection and neutralization of explosive substances using electromagnetic radiation. The problem of detecting explosives is extremely relevant in the modern world. The development of new methods based on the physical principles of the interaction of electromagnetic radiation with matter is a promising area of research. An electrodynamic model of the interaction of an electromagnetic wave with the surface of a VR has been developed. The model takes into account an arbitrary angle of incidence of the wave and two main polarizations – TM and TE. Maxwell’s equations with the corresponding boundary conditions at the interface between two media (air – explosive substance) were used to solve the electrodynamics problems. Different types of explosive substances with different dielectric properties were considered as objects of study. To solve the problem, numerical modeling based on the finite difference method was used. The modeling allowed us to calculate the energy coefficients of reflection, refraction, and absorption of electromagnetic radiation by the explosives. It was found that the efficiency of interaction of an electromagnetic wave with a radiation source significantly depends on the angle of its incidence. The optimal incidence angle for most of the studied radiation sources is in the range of 60 to 75 degrees. For the VRs with low dielectric losses, the influence of the dielectric loss tangent on the imaginary part of the refractive angle is insignificant. This indicates that for such materials the main mechanism of interaction is the reflection of an electromagnetic wave. It has been shown that the energy refractive index has a local extreme (maximum) in the range of incident angles from 65 to 85 degrees. The energy reflection coefficient for a plane electromagnetic wave with vertical polarization increases with the increase of the real part of the relative permittivity according to a law close to the logarithmic law for incident angles less than 60 degrees.
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HASHIMOV, Arif, Allahverdi ORUJOV, and Mehti JAMALOV. "ANALYSIS OF STRUCTURAL CHANGES AND DIELECTRIC PROPERTIES UNDER THERMAL AGING OF CROSS-LINKED POLYETHYLENE USED AS POWER CABLES INSULATION." Energy sustainability: risks and decision making 1, no. 2 (2023). http://dx.doi.org/10.61413/ivln4952.
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Cross-linked polyethylene polymer insulation is widely used as a raw material for insulation of cables. Polyethylene with added peroxide and silane is mostly used. Here, the mechanism of the change of the dielectric loss angle tangent was studied in the case of applying different voltages (in the range of 2-12 kV) to polyethylene samples with added silane and peroxide subjected to heat aging. Combined, i.e., the effect of both thermal aging and applied voltage on the tangent of the dielectric loss angle was investigated during measurements in the frequency range of 50-400 Hz. In the obtained results, it was observed that the value of the dielectric loss angle exceeds the effect of voltage, and the reasons for this increase are mentioned in the article. When we increase the aging period, peaks in the dielectric losses also appeared in the last periods. Also, in the article, the structural change of the insulation was studied by means of Fourier transform infrared spectra (FTIR).
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Wang, Yi, Yuanjun Liu, Chao Yang, and Xiaoming Zhao. "Effect of the cobalt ferrite and carbon fiber powder doping ratio on the electromagnetic properties of coated polyaniline-based polyester–cotton fabric." Textile Research Journal, December 1, 2021, 004051752110608. http://dx.doi.org/10.1177/00405175211060885.
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In this project, firstly, polyaniline-based polyester–cotton fabric was prepared by in situ polymerization using polyester–cotton fabric as the base fabric, aniline as the monomer, ammonium persulfate as the oxidizer, and camphor sulfonic acid as the dopant. Secondly, cobalt ferrite/carbon fiber powder-coated polyaniline-based polyester–cotton fabric was prepared by the textile coating process using polyaniline-based polyester–cotton fabric as the base fabric, PU2540-type polyurethane as the adhesive, and cobalt ferrite and carbon fiber powder as functional particles. Finally, the effect of the cobalt ferrite and carbon fiber powder doping ratio on the shielding effectiveness, reflection loss, dielectric constant real part, imaginary part, and loss angle tangent of cobalt ferrite/carbon fiber powder-coated polyaniline-based polyester–cotton fabric was studied by using the controlled variable method with emphasis on the cobalt ferrite/carbon fiber powder doping ratio. The results show that in the frequency range of 0.01–3.0 GHz, when the doping ratio of cobalt ferrite to carbon fiber powder is 0:3, the reflection loss of cobalt ferrite/carbon fiber powder-coated polyaniline-based polyester–cotton fabric reaches the minimum value at 1.49 GHz, the minimum reflection loss is –21.4 dB, and the effective absorption band is 1.25–1.94 GHz. In the test band, the shielding efficiency, reflection loss, the real part and imaginary part of the dielectric constant, and the loss angle tangent of the carbon fiber powder-coated polyaniline-based polyester–cotton fabric are larger than those of cobalt ferrite-coated polyaniline-based polyester–cotton fabric. The smaller the doping ratio of cobalt ferrite to carbon fiber powder, the larger value of the shielding efficiency, reflection loss, the real part and imaginary part of the dielectric constant, and loss angle tangent of the cobalt ferrite/carbon fiber powder-coated polyaniline-based polyester–cotton fabric.
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Belov, Yu G., V. V. Biryukov, and I. A. Egorov. "Nondestructive method of measurement of laminated plates dielectric parameters." Antennas, 2021. http://dx.doi.org/10.18127/j03209601-202102-11.
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The methods for measuring the parameters of dielectric materials of foil plates have been considered. It has been shown that for “non-destructive measurements” (i.e., without removing the metal foil from the dielectric plate), a method based on the excitation of electromagnetic oscillations in a rectangular plate considered as a resonator can be used. Based on the results of measurements of their resonant frequencies and Q-factors, the relative permittivity and the tangent of the dielectric loss angle of the material can be determined. The calculated relations obtained by the authors of the article in one of the early works using the electrodynamic model of a resonator with “magnetic walls” at the ends have been presented. The Q-factor of the resonator has been calculated by the perturbation method, taking into account the losses in the plate dielectric and metallization layers. The results of measurements for four samples from different dielectrics in the frequency range 200...1000 MHz have been presented. The experimental method has been described, in particular, the method of identifying the type of oscillation, the procedure for processing the measurement results. Due to the high sensitivity of the vector analyzer, measurements have been made with a possible small connection of the resonator (metallized plate) with the measuring circuit. This made it possible to minimize the influence of the coupling elements on the measured Qfactor of the oscillations and to consider this Q-factor close to its own. The presented results are in good agreement with the reference data for the materials. The conducted studies have shown the possibility of using a resonator model with “magnetic walls” at the ends for the analysis of electromagnetic oscillations in a foil dielectric plate and, accordingly, using the relations obtained in this case to determine the parameters of the dielectric plate. The conditions for using this model are the small thickness of the plate in comparison with its transverse dimensions and relatively low operating frequencies. The method, which is based on the calculated ratios of the electrodynamic model of the resonator with “magnetic” walls at the ends, provides a sufficiently high accuracy of determining the relative permittivity of the plate material, which led to the use of it (the method) in practice to control the parameters of foil dielectric plates intended for the manufacture of microwave and UHF-band microcircuits. The studies, the results of which have been presented in this paper, allow us to conclude that this method can also be recommended for determining the tangent of the dielectric loss angle of the plate material.
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Cho, Hanlyun, Younghwan Yang, Dasol Lee, Sunae So, and Junsuk Rho. "Experimental demonstration of broadband negative refraction at visible frequencies by critical layer thickness analysis in a vertical hyperbolic metamaterial." Nanophotonics, September 22, 2021. http://dx.doi.org/10.1515/nanoph-2021-0337.
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Abstract This work presents a vertical hyperbolic metamaterial (vHMM) consisting of a vertically stacked metal-dielectric multilayer that operates in the visible spectrum. The vHMM is designed by exploiting the relation between negative refraction and effective permittivity along the perpendicular direction of the layers (ε ⊥). When a vHMM has a high loss tangent defined by tan δ ⊥ ≡ Im(ε ⊥)/Re(ε ⊥), even a vHMM composed of relatively thick layers can generate negative refraction. A fabricable vHMM composed of gold and copolymer resist (EL8) which exhibits negative refraction at the wavelengths between 450 and 550 nm is designed using critical layer thickness analysis. The largest negative refraction is observed at the wavelength of 500 nm, where the angle of refraction reaches −1.03°. The corresponding loss tangent and equivalent refractive index are 1.08 and −0.47, respectively. However, negative refraction is not observed at the wavelengths longer than 550 nm due to low tan δ ⊥. We uncover that the tan δ ⊥ of a vHMM is the dominant condition for generating negative refraction rather than the ratio of layer thickness to wavelength.
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Luo, Hui, Lingxin Kong, Sihai Lv, et al. "Enhanced Microwave Absorption of Multi‐Interface Core–Shell FeSiAl@MnOx@C Composites by Morphology Engineering." Small, February 10, 2025. https://doi.org/10.1002/smll.202411727.
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AbstractThe rational manipulation of interfacial properties, composition, and morphology of materials has emerged as an effective strategy for enhancing their microwave absorption performance. The crystal phase composition, microstructure, and electromagnetic properties can be regulated by varying the thermal treatment temperature. The synergistic integration of heterogeneous interfaces, magnetic materials, microstructures, and defect engineering helps optimize impedance matching and enhance polarization and magnetic losses. Herein, multi‐interface core–shell FeSiAl@MnOx@C composites with various morphologies demonstrated superior microwave absorption performance. A minimum reflection loss of −56.3 dB is achieved at an absorber thickness of 1.41 mm, and effective absorption bandwidth of 5.0 GHz is obtained at a thickness of 1.59 mm. The radar cross‐section reduction value reached 19.448 at an incidence angle of 0°. The excellent microwave absorption performance is due to the synergistic effect of the significant magnetic and dielectric losses and improved impedance matching. This study establishes a foundation for designing next‐generation high‐performance microwave‐absorbing materials with high magnetic losses.
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Zvezdina, M. Yu, A. M. Shaposhnikova, and Yu A. Shokova. "Effect of climatic factors on energy loss of millimeter range electromagnetic wave in passing through a precipitation layer on the mirror antenna reflector." Radioengineering, 2021. http://dx.doi.org/10.18127/j00338486-202107-14.
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Problem statement. Communication systems transition to the millimeter wavelength range, as well as known theoretical studies on higher electromagnetic energy losses in precipitation in this range compared with the centimeter range have necessitated a scientific justification of an antenna protection method against climatic factors. This makes the chosen research topic relevant. Objective. Analysis of the climatic factors effect on the electromagnetic energy losses in the precipitation layer on the reflector of the millimeter wave range mirror antenna. Results. It is shown that the estimation of electromagnetic energy losses in the precipitation layer on the metal reflector of the mirror antenna should be carried out with the use of the basic statements of meteorological electromagnetism, which unites the statements of electrodynamics and statistical meteorology. Thus, to estimate the electromagnetic energy losses in the precipitation layer on the metal reflector of the millimeter wavelength reflector antenna, the model of the flat multi-layer dielectric coating on the metal screen can be used, which allows to relate the reflection factor to the layer parameters: the electrical parameters of the precipitation (value of the relative permittivity and the tangent angle of dielectric losses) and the layer thickness. Analysis of the known methods of finding the electrical parameters of meteorological precipitation showed that, firstly, it is difficult to measure the imaginary component of the relative permittivity of rain, ice, and snow in the millimeter frequency range. Secondly, there is no approved calculation methodology for the electrical parameters of snow, and the known models depend on random factors - the specific density of snow at the time of measurement and the electrical parameters of the ice and water that make up the snow and their concentrations. Third, finding the electrical characteristics of any type of precipitation characteristic of a given location of the mirror antenna depends on the air temperature. To justify the thickness of precipitation layer on the antenna reflector, the following statistical data are also necessary: the intensity of rain in a given location with a given probability, the daily rate of snow layer and the thickness of ice, which can form in a given climatic region on the metal elements of the mirror structure, including the reflector. Obtained results of electromagnetic energy losses in precipitation layer for different cases of meteorological conditions for millimeter band and their comparison with data for centimeter wavelength range have shown that the greatest losses (from 12-13 dB to 92 dB) in millimeter wavelength range, especially at frequencies above 60 GHz are caused by snow precipitation. In the centimeter wavelength range the maximum losses (up to 10 dB) can be observed in rain.
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Bossavit, Erwan, Huichen Zhang, Nicolas Ledos, et al. "Shaping the Infrared luminescence of Colloidal Nanocrystals Using a Dielectric Microcavity." Advanced Functional Materials, April 10, 2024. http://dx.doi.org/10.1002/adfm.202403532.
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AbstractAs they have gained maturity, colloidal nanocrystals (NCs) have also expand the spectral range over of which they could be used for photonic and optoelectronic applications. In particular, the infrared use of NCs has become of utmost interest to develop cost‐effective alternatives to current technologies. It is then critical not to let the material dictate the light–matter interaction, which is why the coupling of NCs to photonic cavities has been proposed. For infrared NCs, this approach has first been devoted to the control of absorption with in mind the increase of the signal magnitude for detectors. A Lot of efforts have been focused on the use of metallic metasurfaces. However, these generate significant optical losses and yield low quality factor. Here, this study rather focus on the coupling of infrared NCs to a dielectric mirror cavity. HgTe/CdS core‐shell NCs are used and integrated into a cavity made of aperiodic dielectric mirrors. The effect of the substrate is systematically study on spectral linewidth, carrier dynamic, and emission directivity. The cavity is shown to narrow the PL by a factor 10, while focusing the emission over a 12° angle. Monitoring the power dependence of the emission, this study shows that the cavity leads to 250 K increase in the effective electronic temperature.
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Wang, Yi, Yuanjun Liu, Zhenheng Cao, and Xiaoming Zhao. "Effect of doping ratio and amount of polyaniline, cobalt ferrite, and carbon fiber powder on the electromagnetic properties of coated polyester-cotton fabrics." Textile Research Journal, April 26, 2022, 004051752210957. http://dx.doi.org/10.1177/00405175221095738.
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In this project, polyaniline powder was firstly prepared by in situ polymerization using aniline as the monomer, ammonium persulfate as the oxidant, and camphor sulfonic acid as the dopant. Next, polyester-cotton fabrics were used as the base fabrics, polyaniline, cobalt ferrite, and carbon fiber powder as the functional particles, and PU-2540 type polyurethane as the base, and single-layer coated polyester-cotton fabrics were prepared by the textile coating process. Finally, the effects of the polyaniline, cobalt ferrite, and carbon fiber powder doping ratio and functional particle content on the shielding effectiveness, reflection loss, real and imaginary parts of the dielectric constant, and loss angle tangent of single-layer coated polyester-cotton fabrics were focused on using the controlled variable method. The results show that in the frequency range of 0.01–3 GHz, when the doping ratio of polyaniline, cobalt ferrite, and carbon fiber powder is 1:0:3, and when the content of functional particles is 40%, the minimum reflection loss of single-layer coated polyester-cotton fabrics is –22.1 dB at 1.6 GHz, and the effective absorption bandwidth is 1.14 GHz.