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Вид документа : Однотомное издание
Шифр издания :
Автор(ы) : Bobrov P. P., Mironov V. L., Kondratieva O.V., Repin A.V.
Заглавие : Frequency Dependence of Permittivity of Free and Bound Water in Soils for Different Textures
Место публикации : PIERS Online. - 2009. - Vol. 5, № 5. - P.426-430
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Maximova O. A., Lyashchenko S. A., Yakovlev I. A., Varnakov S. N.
Заглавие : Role of interfaces in the permittivity tensor of thin layers of a ferromagnetic metal
Место публикации : JETP Letters. - 2021. - Vol. 114, Is. 3. - P.163-165. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364021150066
Примечания : Cited References: 13. - This work was supported by the Russian Science Foundation, project no. 21-12-00226, http://rscf.ru/project/21-12-00226/
Аннотация: It is known from experimental studies that the components of the permittivity tensor ε depend on layer thicknesses of multilayer thin films, and for nanometer layers, it is necessary to additionally consider the interlayer interfaces. This study provides an answer to the question of what is the reason for the influence of these interfaces on film properties. It is shown that the contribution of interband matrix elements for ferromagnetic films with off-diagonal components of the permittivity tensor determines the ratio between the diagonal and off-diagonal components of the tensor ε at a ferromagnetic layer thickness of about 10 nm.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Leksikov An. A., Tyurnev V. V., Shabanov D. A.
Заглавие : Study of a composite consisting of metal nanoparticles in a dielectric matrix and multilayer bandpass filters based on it
Место публикации : Dokl. Phys. - 2021. - Vol. 66, Is. 3. - P.59-63. - ISSN 10283358, DOI 10.1134/S1028335821030010
Примечания : Cited References: 11. - This study was supported by the Ministry of Science and Higher Education of the Russian Federation within a State Assignment, project no. FEFE-2020-0013 “Development of the Theory of Self-Configuring Machine Learning Algorithms for Modeling and Predicting the Characteristics of Components of Complex Systems”
Аннотация: The frequency and concentration dependences of the effective complex permittivity of a composite consisting of silver nanoparticles in a polystyrene dielectric matrix have been investigated. It has been found that, with an increase in the volume concentration of particles in the composite to ~33%, the real part of its permittivity increases from 2.6 to ~103, while the loss tangent remains no higher than 10–2 up to a frequency of 1 THz. We show the possibility of designing bandpass filters based on composite layered structures, which can be tuned by selecting the particle concentration in the quarter-wavelength layers of the mirrors that ensure the optimal interaction of half-wavelength resonators with each other and the outer resonators with free space. The high contrast between the matrix and the composite permittivities makes it possible to create mirrors with a required reflectivity using a minimum number of layers.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Karavaysky A. Yu.
Заглавие : Shielded open-circuited probe for in-situ measurements of soil permittivity in Very high frequency (VHF) and Ultra high frequency (UHF) bands
Коллективы : SB RAS project [0287-2021-0034]
Место публикации : Trans. Inst. Meas. Control. - 2021. - Vol. 43, Is. 16. - P.3566-3572. - ISSN 0142-3312, DOI 10.1177/01423312211037791. - ISSN 1477-0369(eISSN)
Примечания : Cited References: 30. - The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the SB RAS project No. 0287-2021-0034
Предметные рубрики: DIELECTRIC CHARACTERIZATION
MOISTURE
Аннотация: In this paper, the shielded open-circuited probe operating in the wide frequency range from 75MHz to 2GHz is proposed. The probe is made of an SubMiniature version A (SMA) flange connector. The central rod of the SMA connector emerges from a coaxial transition in the flange and shielded by four rods. The robe design allows us to calculate of the probe reflection coefficient S11 used simple analytical transmission line model (TEM wave mode), the parameters of which were calibrated on a set of substances with a known frequency spectrum of permittivity. The refractive index (RI) and normalized attenuation coefficient (NAC) retrieval technique is based on solving the inverse problem of minimizing the residual norm between measured and calculated frequency spectra of reflection coefficient S11. After calibration, the root-mean-square error (determination coefficient) between the measured and calculated module and phase of the reflection coefficient S11 for the sets of calibration media air, distilled water, butanol, pure ice, water solution with NaCl of salinity of 8.9% do not exceed 0.26dB (0.995) and 0.03 rad (0.999), respectively, in the frequency range from 75MHz to 2GHz. The root-mean-square error (determination coefficient) between the measured RI and NAC spectra for four soil cover samples (variation of the clay fraction from 10.5 g/g to 47.6 g/g) using the proposed probe and a precision coaxial cell not exceeds 0.109 (0.993) and 0.057 (0.986), respectively, in the frequency range from 75 MHz to 2 GHz. As a result, it is experimentally shown that RI и NAC can be measured by the proposed non-precision probe with an error comparable to the precision coaxial cell.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Zeyliger, Anatoly
Заглавие : Application of Sentinel-1B polarimetric observations to soil moisture retrieval using neural networks: Case study for bare Siberian chernozem soil
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-29-05261 mk]; Ministry of Science and Higher Education of the Russian Federation [0287-2021-0034]
Место публикации : Remote Sens. - 2021. - Vol. 13, Is. 17. - Ст.3480. - ISSN 2072-4292(eISSN), DOI 10.3390/rs13173480
Примечания : Cited References: 21. - This work was supported by the Russian Foundation for Basic Research (grant No. 19-29-05261 mk). The field experiment and EC-5 Decagon sensor calibration in laboratory conditions were carried out with the support of Ministry of Science and Higher Education of the Russian Federation, project No. 0287-2021-0034 (basic state assignment)
Предметные рубрики: SURFACE
MODEL
PARAMETERS
ROUGHNESS
INVERSION
DUBOIS
IEM
OH
Аннотация: Sentinel-1 is currently the only synthetic-aperture radar, which radar measurements of the earth’s surface to be carried out, regardless of weather conditions, with high resolution up to 5–40 m and high periodicity from several to 12 days. Sentinel-1 creates a technological platform for the development of new globally remote sensing algorithms of soil moisture, not only for hydrological and climatic model applications, but also on a single field scale for individual farms in precision farming systems used. In this paper, the potential of soil moisture remote sensing using polarimetric Sentinel-1B backscattering observations was studied. As a test site, the fallow agricultural field with bare soil near the Minino village (56.0865°N, 92.6772°E), Krasnoyarsk region, the Russian Federation, was chosen. The relationship between the cross-polarized ratio, reflectivity, and the soil surface roughness established Oh used as a basis for developing the algorithm of soil moisture retrieval with neural networks (NNs) computational model. Two NNs is used as a universal regression technique to establish the relationship between scattering anisotropy, entropy and backscattering coefficients measured by the Sentinel-1B on the one hand and reflectivity on the other. Finally, the soil moisture was found from the soil reflectivity in solving the inverse problem using the Mironov dielectric model. During the field campaign from 21 May to 25 August 2020, it was shown that the proposed approach allows us to predict soil moisture values in the layer thickness of 0.00–0.05 m with the root-mean-square error and determination coefficient not worse than 3% and 0.726, respectively. The validity of the proposed approach needs additional verification on a wider dataset using soils of different textures, a wide range of variations in soil surface roughness, and moisture.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Fokina V. D., Bovina A. F., Bogdanov E. V., Pogoreltsev E. I., Laptash N. M.
Заглавие : Disorder and phase transitions in oxyfluoride (NH4)(3)Ta(O-2)(2)F-4
Место публикации : J. Fluor. Chem. - 2011. - Vol. 132, Is. 10. - P.713-718. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2011.05.012
Примечания : Cited Reference Count: 19. - Гранты: This work was supported by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation (NSh-4645.2010.2).Финансирующая организация: Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation [NSh-4645.2010.2]
Предметные рубрики: HEAT-CAPACITY
COMPLEXES
RB2KTIOF5
FLUORIDES
CRYOLITE
Ключевые слова (''Своб.индексиров.''): cubic oxyfluorides--structural disorder--phase transitions--entropy--permittivity--pressure effect--cubic oxyfluorides--entropy--permittivity--phase transitions--pressure effect--structural disorder
Аннотация: Calorimetric, X-ray, dielectric and DTA under pressure measurements have been performed on oxyfluoride (NH4)(3)Ta(O-2)(2)F-4. The succession of nonferroelectric phase transitions was found associated with the order-disorder processes. The comparative analysis tantalate with related niobate has revealed the important role of the central atom in the physical properties behavior, mechanism of structural distortions and barocaloric effect in oxyfluorides with the eight-coordinated anionic polyhedra. (C) 2011 Elsevier By. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sorokin A. V., Podoprigora V. G., Makarov D. S., Kharlamov D. V., Baltice V. V.
Заглавие : Orientational ordering of tree elements in the dielectric permittivity model of a forest stand
Место публикации : Russ. Phys. J. - 2020. - Vol. 63, Is. 2. - P.238-243. - ISSN 1064-8887, DOI 10.1007/s11182-020-02026-2. - ISSN 1573-9228(eISSN)
Примечания : Cited References: 8
Аннотация: The dielectric characteristics of trees are studied for a dielectric permittivity model of a forest stand of L1 band signals of navigation satellites. The contribution of the orientational ordering of tree elements and of the wood anisotropy to the effective wood dielectric permittivity epsilon has been estimated. The crown layer has the height-depend anisotropy increment epsilon and the orientational ordering of branch tensor elements. The anisotropy gradients in the layer of trunks are determined by the height-dependent wood volume of a single tree and the tree height distribution in a large forest.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bobrov P.P., Mironov V.L., Kondratyeva O.V., Repin A.V.
Заглавие : The Effect of Clay and Organic Mat ter Content on the Dielectric Permittivity of Soils and Grounds at the Frequency Range From 10 Mhz to 1 Ghz
Место публикации : Proceedings IGARSS. - 2010. - С. 4433-4435
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Dudnik A. I., Bogdanova A.V.
Заглавие : Influence of Temperature and Humidity on Resistance and Permittivity of Composite Films of WO3 and B2O3 with Fullerene
Коллективы : International Conference and Seminar on Micro/Nanotechnologies and Electron Devices
Место публикации : 11th Annual International Conference and Seminar on Micro/Nanotechnologies and Electron Devices, EDM'2010: proceedings: IEEE, 2010. - С. 106-108. - (978-1-4244-6626-9). - DOI 10.1109/EDM.2010.5568647
Аннотация: The paper represents dependences of electrical resistance on irradiance and temperature for composite fullerene-WO3 films. It has been shown that the structure film-contacts is more sensitive to external influence when the film is placed between contacts. Dependencies of fullerene doped B2O3 films permittivity on temperature and humidity are given. Introduction of fullerenes results in approximately linear temperature dependence of permittivity
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Mironov V. L., Fomin S. V., Kosolapova L. G., Epikhin A. M.
Заглавие : The Web Site for Retreaving the Microwave Complex Permittivity Spectra of Moist Soils
Коллективы : Progress In Electromagnetics Research Symposium
Серия: PIERS 2011 Suzhou - Progress in Electromagnetics Research Symposium, Proceedings
Место публикации : Proc. PIER. - 2011. - С. 581-584
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fomin S. V., Muzalevskiy K. V.
Заглавие : A dielectric model for frozen mineral soils at a frequency of 435 MHz
Место публикации : Remote Sens. Lett. - 2021. - Vol. 12, Is. 9. - P.944-950. - ISSN 2150704X (ISSN), DOI 10.1080/2150704X.2021.1947537
Примечания : Cited References: 16. - This work was supported by the state assignment of the Ministry of Science and Higher Education of the Russian Federation [project No. 0287-2021-0034]
Аннотация: A single frequency refractive mixing dielectric model at 435 MHz for frozen mineral soils is proposed. The model was created based on the laboratory dielectric measurements of three soil samples in the ranges of soil moisture from 0.01cm3 cm−3 to 0.42cm3 cm−3, temperature from– 30°C to– 1°C, clay content (by weight) from 9.1% to 41.3%. Coefficient of determination R2 and root mean square error (RMSE) predicted by the model and measured values for real () and imaginary () part of the complex relative permittivity (CRP) are = 0.988 (= 0.323) and = 0.987 (= 0.100). Compared to well-known spectroscopic models, this model is simpler in practical engineering use. The input parameters of the model are the volumetric soil moisture, temperature and the content of the clay fraction. The output parameters are the real and imaginary parts of the CRP. The created model may be used to develop new remote sensing retrieval algorithms of temperature, the content of unfrozen water and ice in the root zone of frozen soils for northern regions.ε 'ε ''R2ε 'RMSEε 'R2ε ''RMSEε ''
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mironov V. L., Kosolapova L. G., Fomin S. V., Savin I. V.
Заглавие : Experimental analysis and empirical model of the complex permittivity of five organic soils at 1.4 GHz in the temperature range from −30 °C to 25 °C
Место публикации : IEEE Trans. Geosci. Remote Sensing. - 2019. - Vol. 51, Is. 6. - P.3778 - 3787. - ISSN 0196-2892, DOI 10.1109/TGRS.2018.2887117
Примечания : Cited References: 26. - This work was supported by the Russian Foundation for Basic Research under Grant 16-05-00572.
Аннотация: The dielectric measurements were made for five organic soils taken from the tundra territories of Alaska, Yamal, and Taimyr, with the content of organic matter varying from 35% to 80%. The measurements were carried out in the temperature range from −30 °C to 25 °C, frequencies from 0.45 to 16 GHz and soil moisture from close to zero to the field moisture capacity. The refractive mixing model was applied to fit the measurements of the soil’s complex refractive index (CRI) as a function of soil moisture, with the values of temperature being fixed. As a result, a respective dielectric model was developed. The amounts of bound and transient water in the thawed and frozen soils were introduced as parameters of the developed model and derived as a function of temperature and content of soil organic matter. The other parameters which concern the CRIs of soil solids as well as bound, transient, and liquid soil water or ice components were derived as a function of temperature. The errors of the proposed model estimated in terms of the values of normalized root-mean-sqaure error for the real and imaginary parts of the soil complex relative permittivity appeared to be 6%–7% and 23%, respectively. The proposed dielectric model can be applied in active and passive remote sensing, in particular, for the SMOS, SMAP, and Aquarius missions after testing in ground-based experiments.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnik A. I., Vnukova N. G., Drokin N. A., Bondarev V. S., Shestakov N. P., Tomashevich Y. V., Churilov G. N.
Заглавие : Electrophysical properties of hydroxylated endohedral metallofullerene with gadolinium
Место публикации : J. Phys. Chem. Solids. - 2019. - Vol. 135. - Ст.109094. - ISSN 00223697 (ISSN) , DOI 10.1016/j.jpcs.2019.109094
Примечания : Cited References: 35. - The reported study was funded by RFBR according to the research project No 18-29-19003.
Аннотация: The paper presents the results of experimental measurements of constitutive and electrophysical properties in hydroxylated endohedral metallofullerene with gadolinium sample. We extracted endohedral metallofullerene from carbon condensate, synthesized in high-frequency arc discharge plasma. Later hydroxyl groups were added. Via methods of infrared and x-ray photoelectronic spectroscopy, it was established that the molecules of hydroxylated endohedral metallofullerene have the Gd@C82Ox(OH)y, x + y=(40–42) composition. The method of measuring the electrical impedance in the frequency range from 100 Hz to 100 MHz shows that the resulting hydroxylated fullerene is an ion conductor. The measured frequency dependences of the dielectric permittivity and conductivity of hydroxylated fullerene are explained based on the assumption of an inhomogeneous distribution of electric charges in the material volume. Dielectric-hysteresis loops in the frequency range of 25 Hz–1 MHz and temperature range of 80–300 K, and volt-ampere characteristics were measured. The obtained results imply the appearance of residual polarization induced by the electric field in hydroxylated fullerene. However, the constant dipole moment is absent. © 2019
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Музалевский, Константин Викторович
Заглавие : Особенности радиотеплового излучения мёрзлых тундровых почв в L-диапазоне частот
Место публикации : Журн. радиоэлектрон.: электронный журнал. - 2018. - № 12. - Ст.13. - ISSN 1684-1719, DOI 10.30898/1684-1719.2018.12.13
Примечания : Библиогр.: 30
Ключевые слова (''Своб.индексиров.''): радиометрия--арктика--радиояркостная температура--деятельный слой--диэлектрическая проницаемость--органические почвы--температура почв--влажность почв--radiometry--arctic--radio-brightness temperature--active layer--permittivity--organic soils--soil temperature--soil moisture
Аннотация: В данной работе на основе модифицированной когерентной модели радиотеплового излучения, обобщенной диэлектрической модели почв с высоким содержанием органического вещества изучаются особенности радиотеплового излучения диэлектрически неоднородных неизотермичных тундровых мёрзлых почв на частоте 1,4 ГГц в зависимости от их плотности, влажности и вертикального распределения температуры в поверхностной части деятельного слоя. Показано, что предельная глубина зондирования поверхностной части деятельного слоя тундровых мёрзлых почв зависит от формы профилей температуры, полной объемной влажности и плотности сухого сложения почвы. Исследованы преимущества поляриметрических угловых наблюдений радиояркостной температуры для целей измерения глубинного распределения температуры в поверхностной части деятельного слоя почвы. Дана оценка возможных погрешностей измерения распределения температуры в поверхностной части деятельного слоя почвы.In this paper, a coherent model of thermal microwave emission is proposed, which allows, with an error not worse than 0.51 K and a Pearson coefficient of 0.999, to describe the brightness temperature of a non-isothermal active layer with a layered dielectric constant structure. At a frequency of 1.4 GHz the features of radio-thermal emission of the active tundra topsoil with a high content of organic matter were researched depending on the bulk dry density, moisture content and profile of soil temperature. The proposed coherent model of radiothermal emission and a generalized dielectric model of tundra soil with a high content of organic matter were used in this research. It has been established that the magnitude of the polarization index at fixed values of soil density and moisture is determined only by the surface temperature of the topsoil and does not depend on the kind of temperature profile. The effective temperature of the soil carries the basic information about the heterogeneous structure of the active layer. It is shown that the possibility of identifying various soil temperature profiles, as well as measuring the temperature distribution in the surface part of the active layer of tundra soil can be carried out on the basis of polarimetric angular-dependencies of the radio-brightness temperature with an error of about 3K. At the same time, polarimetric angular-dependencies of brightness temperature also make it possible to determine the sign of the gradient of temperature profiles in the active topsoil. The accuracy of measuring of the soil temperature is limited by the accuracy of radio-brightness temperature observation, the uncertainty of soil moisture and density in the footprint area. If the volumetric soil moisture is known with an error of 0.04 cm3/cm3 or the soil density - with an error of 0.1 g/cm3, then the error in temperature retrieval increases by factors of 2 and 1.5, respectively, in the soil moisture range of 0.2-0.4 cm3/cm3 and 0.4-0.6 cm3/cm3. It is shown that for characteri stic temperature gradients of 0.4-1ºС/cm in the active topsoil thickness of 10 cm the thickness of the tundra soil layer forming the thermal radiation decreases by factor of 2.5 from 10cm to 4 cm at increasing of surface soil temperature from -30ºС ÷ -20º С to -10º С ÷-5º С in the case of given values of soil density and moisture of 0.15 g/cm3 and 0.42 cm3/cm3, respectively. For all the temperature profiles considered, the thickness of the emission layer linearly decreases by factor of 1.5 with an increasing of soil moisture content by factor of 3 from 0.2 cm3/cm3 to 0.6 cm3/cm3, and with an increasing of soil density more than 10 times from 0.05 cm3/cm3 to 0.8 cm3/cm3, the thickness of the emission layer decreases by factor of 3. In the future, the authors plan to investigate issues related to the formation of radio-thermal emission from the active layer of frozen soils, taking into account the density and moisture profiles in the organic and mineral horizon of the tundra active topsoil.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Маркевич И. А., Селютин Г. Е., Дрокин, Николай Александрович, Беляев, Борис Афанасьевич
Заглавие : Синтез и электрофизические свойства композитов на основе сверхвысокомолекулярного полиэтилена и углеродных нанотрубок
Место публикации : Журн. СФУ. Техн. и технол. - 2018. - Т. 11, № 2. - С. 190-197. - ISSN 1999-494X, DOI 10.17516/1999-494X-0022; J. Sib. Fed. Univ. Eng. Technol.
Примечания : Библиогр.: 8. - Работа выполнена при поддержке Фонда содействия развитию малых форм предприятий в научно-технической сфере в рамках договора № 9594ГУ/2015 от 01.02.2016.
Ключевые слова (''Своб.индексиров.''): композиты--сверхвысокомолекулярный полиэтилен--углеродные нанотрубки--диэлектрическая проницаемость--проводимость--composites--ultrahigh-molecular-weight polyethylene--carbon nanotubes--dielectric permittivity--conductivity
Аннотация: Получены композиты на основе сверхвысокомолекулярного полиэтилена и углеродных нанотрубок методом смешивания компонентов в ксилоле при определенных температурах. Комплексные проводимости и диэлектрические проницаемости образцов материалов измерены в диапазоне частот от 100 Гц до 1 ГГц. Установлены условия синтеза как электропроводящих, так и диэлектрических композитов. При этом величина проводимости зависит не только от концентрации углеродных нанотрубок, но и от структуры их распределения в полимерной матрице, которая, в свою очередь, зависит от температурных условий получения композита.Composites based on ultrahigh-molecular-weight polyethylene and carbon nanotubes were obtained by mixing the components in xylene at certain temperatures. The complex conductivities and permittivities of the material samples were measured in the frequency range from 100 Hz to 1 GHz. The conditions for the synthesis of both electrically conducting and dielectric composites were established. The conductivity depends not only on the concentration of carbon nanotubes, but also on the structure of their distribution in the polymer matrix, which in turn depends on the temperature conditions for obtaining the composite.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Tyurnev V. V.
Заглавие : Electrodynamic calculation of effective electromagnetic parameters of a dielectric medium with metallic nanoparticles of a given size
Место публикации : J. Exp. Theor. Phys. - 2018. - Vol. 127, Is. 4. - P.608-619. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776118100114
Примечания : Cited References: 31. - This work was supported by the Ministry of Education and Science of the Russian Federation (contract no. 14.575.21.0142; unique identifier of the project is RFMEFI57517X0142).
Ключевые слова (''Своб.индексиров.''): electromagnetic fields--magnetic susceptibility--metals--nanoparticles--natural frequencies--permittivity
Аннотация: The frequency dependence of the effective complex permittivity and effective complex permeability of a heterostructure based on a dielectric medium containing metallic nanoparticles of spherical shape is calculated by an original method. In contrast to the Bruggeman [21] and the Maxwell Garnett [17] approaches, which use the quasi-static approximation in calculations, a nonuniform distribution of electromagnetic fields inside metallic particles is calculated, which allows the analysis of the electromagnetic parameters of the heterostructure not only as a function of frequency but also as a function of the nanoparticle size. It is shown that the plasmon resonant frequency decreases with increasing both the size and the concentration of particles in the heterostructure. It is also shown that a dielectric medium containing nonmagnetic metallic nanoparticles exhibits diamagnetic properties. In this case, the position of the maximum on the frequency dependence of the imaginary part of the magnetic susceptibility coincides with the relaxation frequency of charge carriers. The calculated spectra of the real and imaginary components of the permittivity of the heterostructure with a size of metallic particles less than 10 nm are in good agreement with Bruggeman calculations; however, the agreement with Maxwell Garnett calculations is observed only at nanoparticle concentrations lower than 10–6.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V.
Заглавие : A new method for remote sensing of moisture profiles in the arable layer at three frequencies; experimental case study
Место публикации : Int. J. Remote Sens. - 2021. - Vol. 42, Is. 7. - P.2377-2390. - ISSN 01431161 (ISSN), DOI 10.1080/01431161.2020.1851795
Примечания : Cited References: 35. - This work was supported by the Russian Foundation for Basic Research (grant No. 18-05-00405) in part of the sensing depth investigation and retrieving soil moisture. The method of the formation of radio impulses was created in part of SB RAS project No. 0356-2019-0004
Аннотация: In this paper, the possibilities of remote sensing of moisture profiles in the arable layer were theoretically and experimentally studied based on the nadir measurements of reflection coefficients at three frequencies of 1.26 GHz, 796 MHz and 641 MHz. The reflection coefficients were measured by the impulse method during natural cycles of evaporation and moistening of an arable layer at the agricultural field being under steam, located at 56°05ʹN, 92°40ʹ E in the area of the Minino village, Krasnoyarsk region, the Russian Federation. The soil moisture profiles were retrieved in the course of solving the inverse problem, in which the reflection coefficients at different frequencies acted as an informative sign. The root-mean-square error and the determination coefficient (R 2) between retrieved and measured moisture values in the topsoil thickness of 0.15 m were 3.3% and 0.79, respectively. In the course of theoretical calculations, it was shown that in practice, it is impossible to predict the sensing depth of the arable layer without preliminary information on the form of moisture profile. Moreover, the sensing depth depends not only on the form of soil moisture profile but also on frequency. In this regard, it is impossible to correlate the effective soil moisture, retrieved from single-frequency measurements of the reflection coefficient in the approximation of homogeneous topsoil, with the specific thickness of topsoil. The study shows the promise of developing multi-frequency radar systems for remote sensing of soil moisture profiles in the arable layer, the potential of which can be realized on lightweight unmanned area vehicle (UAV) platforms.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maximova O. A., Ovchinnikov S. G., Lyashchenko S. A.
Заглавие : Analytical calculation of dielectric permittivity tensor from magneto-optical ellipsometry measurements
Коллективы : Government of the Russian Federation [075-15-2019-1886]
Место публикации : J. Phys. A: IOP PUBLISHING LTD, 2021. - Vol. 54, Is. 29. - Ст.295201. - ISSN 1751-8113, DOI 10.1088/1751-8121/abfe72. - ISSN 1751-8121(eISSN)
Примечания : Cited References: 24. - This study was supported by the Government of the Russian Federation (Agreement No. 075-15-2019-1886)
Предметные рубрики: FILMS
Аннотация: Magneto-optical ellipsometry combines ellipsometry and magneto-optical Kerr effect measurements which are two powerful techniques. The main difficulty is usually in data processing as a number of parameters should be extracted from measured ellipsometric (ψ, Δ) and magneto-ellipsometric (δψ, δΔ) parameters. Standard procedure of solving magneto-ellipsometry equations involves numerical calculations. In this paper we show that it is possible to find out all elements of dielectric permittivity tensor without numerical calculation methods. It means that the inverse problem of magneto-optical ellipsometry can be solved analytically in the case of expansion of magneto-ellipsometric parameters δψ and δΔ with respect to two small parameters. We present a full set of mathematical expressions that enable us to calculate complex refraction index and complex magneto-optical parameter of a sample from magneto-optical ellipsometry measurements, thereby obtaining diagonal and off-diagonal complex elements of dielectric permittivity tensor. This analytical approach can be used in case of the contribution from magnetism into reflection coefficients being small.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Markevich I. A., Selyutin G. E., Drokin N. A., Selyutin A. G.
Заглавие : Electrical and mechanical properties of the high-permittivity ultra-high-molecular-weight polyethylene-based composite modified by carbon nanotubes
Место публикации : Tech. Phys. - 2020. - Vol. 65, Is. 7. - P.1106-1113. - ISSN 10637842 (ISSN), DOI 10.1134/S1063784220070129
Примечания : Cited References: 39
Аннотация: A composite based on ultra-high-molecular-weight polyethylene (UHMWPE) added with 1 wt % of multiwalled carbon nanotubes (MWCNTs) with a high permittivity (ε = 4.5) and a low dielectric loss (tanδ = 10–2) in the frequency range from 100 Hz to 100 MHz has been synthesized, and its main mechanical characteristics have been studied. The material has a low (22 MPa) breaking strength, a high (700%) tensile elongation, and an abrasion resistance higher than that of pure UHMWPE by 37%. It is shown using the X-ray diffraction and differential scanning calorimetry data that the changes in the mechanical properties of the composite are related to the changes in the polymer matrix structure under the action of the high-intensity ultrasonic radiation used for embedding MWCNTs into the polymer.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lepeshev A. A., Pavlov A. V., Drokin N. A., Malkin A. I., Kiiko V. S., Knyazev N. S.
Заглавие : Features of the Preparation and Study of Electrophysical Characteristics (BeO+TiO2)-Ceramics by Impedance Spectroscopy
Место публикации : Refract. Ind. Ceram. - 2019. - Vol. 60, Is. 3. - P.309-317. - ISSN 1083-4877, DOI 10.1007/s11148-019-00359-1. - ISSN 1573-9139 (eISSN)
Примечания : Cited References: 26
Аннотация: An electrically conducting two-component BeO-ceramic with the addition of micro- and nano-crystalline TiO2 powder is prepared that can be used as a material for scattered microwave radiation absorption in high-power electronic devices. The nature of the occurrence of electrical conductivity and absorption of the microwave field in (BeO + TiO2)-ceramics is not completely established. Impedance spectroscopy is used for the first time to investigate the electrical and dielectric characteristics of this ceramic in the frequency range from 100 Hz to 100 MHz in relation to presence of micro- and nano-sized TiO2 phase within the BeO ceramic composition. It is established that the static resistance of ceramics with addition of a TiO2 nanopowder is significantly reduced compared with the resistance of original ceramic with TiO2 micropowder. It is shown that real and imaginary components of the dielectric constant of the ceramic studied increase to abnormally large values with a reduction in frequency of the effective electric field, and in the high frequency range f ≥ 108 Hz the process of dielectric relaxation commences leading to an increase in dielectric loss angle. Dielectric properties of ceramic samples are determined under blocking conditions for through conduction. The effect of TiO2 micropowder additions on dielectric polarization processes with frequency increasing up to 12 × 109 Hz is considered.
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