Non-resonant wave front reversal of spin waves used for microwave signal processing

It is demonstrated that non-resonant wave front reversal (WFR) of spin-wave pulses caused by pulsed parametric pumping can be effectively used for microwave signal processing. When the frequency band of signal amplification by pumping is narrower than the spectral width of the signal, the non-resonant WFR can be used for the analysis of the signal spectrum. In the opposite case the non-resonant WFR can be used for active (with amplification) filtering of the input signal.Comment: 4 pages, 3 figure

Design methodology for immersive educational resources

Based on the analysis of sources on the problem of research, the article defines types of electronic educational resources (EER), general requirements for them, focuses on didactic and methodological requirements and existing holistic systems of psychological and pedagogical requirements for EER, presents the main types of parameters that can be used to evaluate the quality of EER, analyzes the typical structure of EER and characterizes its components. The analysis of approaches to defining the concepts of ``immersiveness'', ``immersive educational environment'', ``immersive approach in education'', ``immersive educational resources'' (IER) was carried out, on the basis of which the relationship between the virtual environment and immersive learning environment was determined, the pedagogical aspects of learning in immersive environments were considered, the classification of IER was made. The main components of IER design and implementation are analyzed, and the essence of IER design and IER design methodology is determined.In the main part of the proposed general model of the methodology of IOR design and analyzed the goals, subjects of methods, stages, and content of training, forms of organization of the educational process, methods, teaching tools, and predicted results of the methodology.In the conclusion the elements of the methodology of IЕR design are presented, in particular, a complex IЕR in the form of a distance learning course, examples of designing prototypes of immersive teaching materials, etc. are considered.Based on the analysis of sources on the problem of research, the article defines types of electronic educational resources (EER), general requirements for them, focuses on didactic and methodological requirements and existing holistic systems of psychological and pedagogical requirements for EER, presents the main types of parameters that can be used to evaluate the quality of EER, analyzes the typical structure of EER and characterizes its components. The analysis of approaches to defining the concepts of ``immersiveness'', ``immersive educational environment'', ``immersive approach in education'', ``immersive educational resources'' (IER) was carried out, on the basis of which the relationship between the virtual environment and immersive learning environment was determined, the pedagogical aspects of learning in immersive environments were considered, the classification of IER was made. The main components of IER design and implementation are analyzed, and the essence of IER design and IER design methodology is determined.In the main part of the proposed general model of the methodology of IOR design and analyzed the goals, subjects of methods, stages, and content of training, forms of organization of the educational process, methods, teaching tools, and predicted results of the methodology.In the conclusion the elements of the methodology of IЕR design are presented, in particular, a complex IЕR in the form of a distance learning course, examples of designing prototypes of immersive teaching materials, etc. are considered

Magnetostatic correlator of microwave signals with the internal wave front reversal

A new technique of the correlation processing of data based on the nonlinear interaction of signals of backward volume magnetostatic waves in yttrium-iron garnet thin films and a corresponding laboratory mock-up of the correlation receiver operating in the 6 cm wavelength range have been presented in this paper. It was proposed to use additional pumping pulse for obtaining a time-reversed signal pulse. The resultant correlation signal occurred during the nonlinear interaction of the delayed signal wave and the pumping-reversed wave. The specificity of the passage of broadband signals through the resonance system of waveguide of spin waves was taken into account. It has been found out that the resonance properties of the correlator affect the efficiency of the desired signal separation from the noise level. The resultant signal-to-noise ratio for the output signal was enhanced by more than 20 dB

Результати натурного випробування на міцність стрілочного переводу типу Р65 марки 1/9 проекту 65109Ж-01

The results of full-scale test of the strength of the switch type R65, mark 1/9 of the design 65109Zh-01 are presented.Изложены результаты натурного испытания на прочность стрелочного перевода типа Р65 марки 1/9 проекта 65109Ж-01.Наведено результати натурного випробування на міцність стрілочного переводу типу Р65 марки 1/9 проекту 65109Ж-01

RESULTS OF FIELD STUDIES ON THE STRENGTH SWITCH TYPE R65 BRAND 1/9 PROJECT 65109 W-01

The results of full-scale test of the strength of the switch type R65, mark 1/9 of the design 65109Zh-01 are presented

Дослідження Li-Al феритів методами ядерного магнітного резонансу, UV спектроскопії і мессбауерівської спектроскопії

У роботі представлені результати досліджень літієвих феритів, заміщених іонами алюмінію методами ядерного магнітного резонансу (NMR), мессбауерівської спектроскопії та за допомогою вібраційного магнетометра зразків при кімнатній температурі. Результуючий магнітний момент системи залежить як від вмісту заміщуючого елементу, так і від селективного входження в А чи В підгратку. Катіони AL3+ і Li+ переважно займають октаедричні (В) позиції, тоді як Fe3+ розподілений по обох позиціях. Впровадження Al3+ в Впозиції понижує інтенсивність IFNMR амплітуди ехо. Більше того, збільшення вмісту алюмінію зменшує значення магнітного надобмінного поля і спричиняє швидке зростання парамагнітної компоненти (дублет на мессбауерівських спектрах). Зменшення намагніченості насичення призводить до зменшення інтенсивності сигналу. Наші результати показали, що NMR і мессбауерівська спектроскопія є доповняльними методиками для опису магнітних властивостей Li-Al феритів в широкому околі частот. Дослідження деградації метилену синього у водному середовищі показали, що синтезований ферит здатний витупати як фотокаталізатор, що працює у видимому діапазоні освітлення. Показано, що оптична ширина забороненої зони і коефіцієнт деградації знаходяться в оберненій залежності.The paper presents the study of lithium ferrites substituted by aluminum ions by the methods of nuclear magnetic resonance (NMR), Mössbauer spectroscopy, and using a vibrating magnetometer of samples at room temperature. The resulting magnetic moment of the system depends both on the content of the substituting element and on the selective injection into the A or B sublattice. Al3+ and Li+ cations occupy octahedral (B) sites, while Fe3+ is distributed in both ones. Implementation of Al3+ in the B-position reduces the intensity of the IFNMR echo amplitude. Moreover, an increase in the aluminum content reduces the value of the magnetic superexchange field and causes rapid growth of the paramagnetic component (doublet in Mössbauer spectra). A decrease in saturation magnetization leads to a decrease in signal intensity. Our results showed that NMR and Mössbauer spectroscopy are complementary techniques for describing the magnetic properties of Li-Al ferrites in a wide range of frequencies. Studies of the degradation of methylene blue in an aqueous medium have shown that the synthesized ferrite can act as a photocatalyst operating in the visible light range. It is shown that the optical band gap and the degradation coefficient are inversely related

Structure, Optical and Electric Properties of Opal-Bismuth Silicate Nanocomposites

Synthetic opals composed of 300 nm silica spheres are impregnated with a Bi₁₂SiO₂₀ melt at 1190 K. Structure and properties of the as-prepared samples are studied by employing the scanning electron microscopy, X-ray diffraction, and optical spectroscopy and direct current conductivity techniques. The nanocomposites are found to be multi-phase systems composed of Bi₁₂SiO₂₀, Bi₄Si₃O₁₂ and SiO₂ crystallites with an average linear size not less than 20 nm. Formation of Bi₄Si₃O₁₂ crystallites becomes possible as a result of changing in the Bi₂O₃-SiO₂ molar ratio due to the melting of silica spheres. The Raman intensity redistribution observed by surface scanning may be caused by both composition inhomogeneity and concentration of the exciting radiation field at composite defects. The "red" shift of photoluminescence band is observed. Activation energy of direct current conductivity is estimated as 1.1 eV