Experimental Substantiation of The Possibility of Hydrolytic Lignin Using in the Architectural Electromagnetic Shielding Systems

The article presents the research results of electromagnetic radiation reflection and transmission characteristics in the frequency range 0.7–17.0 GHz of the hydrolytic lignin, impregnated to saturation with the electrolyte water solution, at different temperatures of this material. The research is aimed at simultaneously solving of two problems: 1) search for new inexpensive materials for electromagnetic shielding; 2) experimental substantiation of a new promising method of hydrolysis lignin utilization. Based on the research results, it is possible to conclude the hydrolytic lignin is prospective for use for the manufacture of moisture-containing materials that attenuate electromagnetic radiation energy. Such materials could be used in the architectural electromagnetic shielding systems (including in the systems operating under conditions other than standard) in the form of filler for air gaps of walls and floors or filler for the building mixtures. In practice, such systems are used for protection radioelectronic equipment or people, located inside of the buildings, from the impact of external electromagnetic radiation

High-Frequency Electrodynamics of Slow-Moving Limited Media Taking into Account the Additional Specular Reflection

The paper presents the results of constructing the physical and mathematical model of highfrequency electromagnetic waves propagation in slowly moving media of finite dimensions, which takes into account the phenomena of specular reflection of these waves. The constructed model is based on eqations designed to determine the speed of electromagnetic waves propagation in slowly moving media of finite dimensions, as well as on equations designed to describe these waves. The feature of these equations lies in the fact that they take into account the Fresnel drag coefficient for electromagnetic waves propagation speed, while the speed of the media isn’t constant, it can depend on time and coordinates. An approach to these equations solving has been developed, as well as an approach to modeling the process of electromagnetic waves propagation in slowly moving media of finite dimensions, based on the use of a difference scheme, in which the motion of these media is taken into account using infinitesimal Lorentz transformations in a difference cell. It has been determined that the developed model and approaches can be used to solve problems associated with the construction of transmitting and receiving paths of radio communication systems and information transmission through moving plasma streams, gas clouds, macroscopic plasma clots, as well as in solving problems of aeroacoustics

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ВЗАИМОДЕЙСТВИЯ ЭЛЕКТРОМАГНИТНЫХ ВОЛН С МИКРОПОРИСТОЙ СТРУКТУРОЙ ПОГЛОТИТЕЛЯ

Сonsistent physics and mathematics model of electromagnetic waves propagation in heterogeneous medium using the generalized wave equation and the Dirichlet theorem is built. The data of numerical simulation of the electromagnetic interference interaction with a fibrous material having a double porosity. The results of numerical simulation show that the presence of micro- and macropores (medium with double porosity) of the fabric ensures maximum masking effect.Построена согласованная физико-математическая модель распространения электромагнитных волн в гетерогенной среде с использованием обобщенного волнового уравнения и теоремы Дирихле. Приведены данные численного моделирования взаимодействия электромагнитного излучения с волокнистым материалом, имеющим двойную пористость. Результаты численного моделирования показывают, что наличие микро- и макропор (среды с двойной пористостью) в ткани обеспечивает максимальный маскирующий эффект

Regularities of Nanofocusing of the Electromagnetic Field of a Fractal Rough Surface

A consistent physical and mathematical model of the propagation of electromagnetic waves in an inhomogeneous medium with strong discontinuities of the electromagnetic field at the interface of two media, which is a rough surface, was developed. Mathematical modeling of rough surfaces and their profiles was carried out using fractal geometry, which allows us to display the topology of the object as close as possible to reality. For real heterogeneous rough structures, we have developed a through-counting method that takes into account the continuity of the total current at the interfaces of adjacent media, the effect of induced surface charge and surface current. This approach lets one avoid the necessity to set surface impedances depending on the structure of the field being determined and on the material properties

К проблеме неизотермического влагопереноса в капиллярно-пористых средах

A mathematical model of moisture transfer in capillary-porous media is proposed. It is based on the equations of twophase filtration, isotherms of moisture sorption, thermodynamic equations of Kelvin and Klapeirone - Klausius . The numerical method of moisture transfer equations solving is developed on the basis of weighted residuals method. The results obtained can be used for simulation of heat and mass transfer in different technological processes, in building, food and chemical industry, and in agrophysics also.Предложена математическая модель тепловлагопереноса в капиллярно-пористых средах, базирующаяся на уравнениях двухфазной фильтрации, изотермах сорбции влаги, термодинамических уравнениях Кельвина и Клапейрона - Клаузиуса. Разработан численный метод решения уравнений тепловлагопереноса, базирующийся на методе взвешенных невязок. Полученные результаты могут быть использованы для моделирования тепломассопереноса в различных технологических процессах, в строительной, пищевой и химической промышленности, а также в агрофизике

СНИЖЕНИЕ КОЭФФИЦИЕНТА ОТРАЖЕНИЯ МНОГОСЛОЙНОЙ КОНСТРУКЦИИ ЭКРАНА ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ НА ОСНОВЕ ВЛАГОСОДЕРЖАЩИХ МАТЕРИАЛОВ

The theoretical and experimental justification for creating a multilayer EMR shield based on moisture-containing materials is presented, the reflection coefficient of the electromagnetic wave for which is reduced from -1.5 to -6 dB in the range 8…12 GHz is given. The obtained result is achieved due to a stepwise change in the electromagnetic characteristics by increasing the concentration of the filler.Приведено теоретические и экспериментальное обоснование создания многослойного экрана ЭМИ на основе влагосодержащих материалов, коэффициент отражения электромагнитной волны для которого снижен с -1,5 до -6 дБ в диапазоне 8…12 ГГц. Полученный результат достигнут за счет ступенчатого изменения электромагнитных характеристик путем увеличения концентрации наполнителя

Oб измерении электрического сопротивления жидких электролитов аккумуляторных батарей

Operational control of parameters of electrolytes (first of all–of specific electric conductivity), is an important electrochemical technology. The methods of measurement of electric conductivity of electrolytes is a subject of permanent discussions because of complexity of physical-and-chemical processes accompanying ion transport and of electrolyte polarization near surfaces of electrodes and of electrochemical processes on the electrodes surfaces. Actual highand low-frequency conductometric methods require relatively expensive equipment and are not free of methodological flaws. In this paper a new method of electric resistance of liquid electrolytes is described and substantiated. It is based on automatic performance of a series of measurements of electrolyte resistance at DC, data processing and extrapolation of an appropriate dependence to threshold voltage at measurement cell plates. The character of functions approximating resistance-applied voltage dependence and method of resistance determination are substantiated. The measurements of specific resistance of some electrolytes were performed. The advantages of the proposed method and measuring device are their simplicity, cheapness, reliability and, consequently, wider possibility to utilize it at technological lines and processes, even at such sites of production processes where such a control was impractical earlier. The method can be widely used for express-diagnostics of electrolytes in such areas as electrochemical energy storage, medicine, agriculture, chemical industry, food production.. Важным элементом электрохимических технологий является оперативный контроль параметров используемых электролитов и прежде всего удельной электропроводности. Методы измерения электропроводности электролитов вызывают вопросы ввиду сложности физико-химических процессов переноса ионов, поляризации электролита вблизи поверхности электродов и электрохимических процессов на их поверхности. Применяемые высоко и низкочастотные методы кондуктометрии требуют достаточно дорогого оборудования и не лишены методологических недостатков. В статье обоснован новый метод измерения сопротивления электролитов, основанный на автоматическом выполнении серии измерений проводимости при постоянном токе, обработке данных и экстраполяции измерений к пороговому напряжению на обкладках измерительной ячейки. Обоснованы характер функций и методика определения электрического сопротивления электролита на основе данных измерений сопротивления ячейки при разных напряжениях на ней. Проведены измерения удельного сопротивления некоторых электролитов. Преимуществами предлагаемого метода и реализующего его прибора являются простота, дешевизна и, следовательно, возможность использования на таких участках производства, где ранее подобный контроль был бы нецелесообразен. Метод может найти широкое применение для экспресс-диагностики электролитов в таких сферах, как электрохимические накопители энергии, медицина, сельское хозяйство, химическая промышленность, производство продовольственных товаров

Numerical modeling of the ELECTROMAGNETIC WAVES interaction with microporous structure absorber

Сonsistent physics and mathematics model of electromagnetic waves propagation in heterogeneous medium using the generalized wave equation and the Dirichlet theorem is built. The data of numerical simulation of the electromagnetic interference interaction with a fibrous material having a double porosity. The results of numerical simulation show that the presence of micro- and macropores (medium with double porosity) of the fabric ensures maximum masking effect