Suitability of variance shift keying for real conditions

This paper investigates the possibility of real-life using the brand new type of digital modulation, which implies the transmission of white Gaussian noise whose variance changes in time. That modulation has been entitled as variance shift keying. The signals obtained on its basis have a high level of transmission security, and they even cannot be detected by standard means of matched filtering. However, the paper suggests the decision on how to process these signals at the receiver site. It is proposed to use a specially developed optimal receiver, whose restoration quality appears to be better in comparison with the conventional cumulative receiver. The digital simulation of propagation in frequency selective media has shown the signal with variance shift keying is possible to be used in real conditions since its distribution of instantaneous amplitudes remains Gaussian. © 2018 Academic Mind.The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0006. The research was executed by the grant of the Ministry of education and science of the Russian Federation (project № 8.2538.2017/4.6)

Effects of using metamaterial in waveguide design

Исследовано понятие метаматериала, описывается его суть, приведены свойства и причины их возникновения. Представлены различные варианты исполнения метаматериалов, дана методика расчета их резонансной частоты. Вводятся понятия отрицательной групповой скорости, левой среды, прямой и обратной волн. Исследованы эффекты применения метаматериалов в конструкциях волноводов различного рода и форм поперечного сечения. Проанализировано влияние ориентации включений относительно падающей волны на характеристики направляющей структуры. Сделан вывод о возможности использования волновода, заполненного метаматериалом, в основе конструкции антенны вытекающих волн.A concept of metamaterials is investigated, its essence is described, properties and its causes are shown. Different versions of metamaterials are presented, and calculation method of resonant frequency is given. The concepts of negative group velocity, left-handed media, forward and backward wave are introduced. Effects of using metamaterials in design of the various waveguides with the different cross section form are investigated. An influence of inclusions orientation relative to an incident wave on the guided structure performances is analyzed. The conclusion about possibility of using metamaterial loaded waveguide as a leaky-wave antenna base is made

Construction optimization of fire sheet of exhaust boilers

В работе представлены результаты натурного эксперимента и численных расчетов по оценке влияния качества сварного соединения на температурный режим огневого листа, используемого в качестве поверхностей нагрева в котлах утилизаторах. Разработанная и верифицированная по результатам эксперимента модель позволяет рассчитать температурное поле при любых размерах и сочетаниях материалов элементов конструкции. Проведено сравнение полученных максимальных температур в огневом листе и в экранах из стандартных плавниковых труб при аналогичных граничных условиях.The work presents results of experiment and numerical simulations of a weld quality influence on fire sheet temperature regime, which used as a heating surface in exhaust boilers. The model designed and verified by the results of experiments allows to calculate the temperature field of fire sheet of any sizes and combinations of construction elements materials. A comparison of the maximum temperature in the firing sheet and heating surfaces of standard fin tubes under similar boundary conditions presented

Restoration of Static JPEG Images and RGB Video Frames by Means of Nonlinear Filtering in Conditions of Gaussian and Non-Gaussian Noise

The use of nonlinear Markov process filtering makes it possible to restore both video stream frames and static photos at the stage of preprocessing. The present paper reflects the results of research in comparison of these types image filtering quality by means of special algorithm when Gaussian or non-Gaussian noises acting. Examples of filter operation at different values of signal-to-noise ratio are presented. A comparative analysis has been performed, and the best filtered kind of noise has been defined. It has been shown the quality of developed algorithm is much better than quality of adaptive one for RGB signal filtering at the same a priori information about the signal. Also, an advantage over median filter takes a place when both fluctuation and pulse noise filtering. ©2017. American Geophysical Union. All Rights Reserved

Thermo-chemical treatment of iron based composite electroplates

A scheme of renovating and hardening the parts with the use of composite electrochemical coatings is described. The powders of CrB 2 and Al 2O 3 serve as a dispersed phase in the electrodeposited coating from electrolytes containing FeCl 2 and FeSO 4. Chemical-and-thermal treatment (CTT) of parts was carried out at 210°C via sulfonitriding. Comparative tests of modified coatings and St45 for wear resistance in contact with 12KhN4A steel as a counterbody and for corrosion showed the improved characteristics after CTT

The effect of electrolyte composition on structure and properties of composite electrochemical coatings with copper matrix

A problem of wear resistance and hardness improvement is considered for copper coatings. Copper plating electrolyte is modified with addition of amine complexing agents and TiO 2 dispersed phase. Role of electrolyte composition and dispersed phase nature in structure forming and properties of composite electrochemical coatings Cu-TiO 2 is investigated. Diffraction layer-by-layer investigation of the composite coatings shows uniform distribution of dispersed phase in the deposit bulk and surface. The wear resistance of coatings is increased by 30-35%

Development and research of data transmission system using M-sequence

В исследовании синтезируется система передачи данных высокой помехозащищенности. Разработаны передающее и приемное устройства, реализующие метод расширения спектра, осуществляющие кодирование и декодирование передаваемого сообщения М-последовательностью. Схемы синтезированы в среде SysGen, эксперимент проведен на ПЛИС фирмы XILINX семейства Kintex7. Получение данных передатчиком осуществлялось с помощью стандарта «UART» со скоростью передачи 1,5 Мб/с. Эксперимент установил, что работоспособность системы ограничивается отношением мощности сигнала и помехи равной -14 дБ.A data transmission system with high noise immunity is synthesized. Transmitting and receiving devices, implementing the spread spectrum and carrying out transmitted message encoding and decoding by m‑sequence, are designed. Schemes are synthesized by using the SysGen software. The experiment is performed with Kintex7 PLD developed by XILINX. The system is based on the use of the standard «UART» with a rate of 1.5 Mbit/s. The experiment found that the system performance is limited by the signal-to-noise ratio equaled to -14 dB

Ascent of volatile-rich felsic magma in dykes:a numerical model applied to deep-sourced porphyry intrusions

Dyke propagation is a mechanism for more rapid ascent of felsic magmas through the crust than is possible via diapirs or percolative flow. As it ascends, the magma undergoes complex physical and chemical transformations induced by decompression and cooling. These processes dramatically change the magma density and viscosity, which in turn affect magma ascent rate and the depth at which the dyke arrests. We present a mathematical model of dyke propagation for silicic magmas taking into account the presence of multiple volatile species (H2O and CO2), bubble growth, heat advection and loss, crystallization and latent heat release. We consider conditions for dykes associated with porphyry ore deposits, which may represent an end-member in rapid ascent of felsic magmas from depth. In particular, we simulate the propagation of dykes launched from a deep (900 MPa), volatile-saturated magma source, testing the effects of the magma H2O/CO2 content, temperature and mass on its ascent rate and final emplacement depth. The model predicts short ascent times (hours to days), with a large increase in viscosity at shallow depth, leading to stagnation and solidification of the dyke. Higher initial water content, higher temperature and larger mass of the magma in the dyke promote faster propagation and shallower arrest. Volatile loss from ascending magma remains limited until the stagnation depth, providing a potential mechanism for transfer of deep volatiles to hypabyssal blind intrusions associated with porphyry ore deposits. Our findings are applicable to the problem of silicic magma ascent through the crust more generally

Comparative study of an activity of rat spinal ganglion cells and PC12 cells on the surfaces modified with bioadhesive polymers

We studied the adsorption of bioadhesive polymers (polyornithine, gelatin, laminin) on polystyrene surface by the use of dynamic light scattering. The contribution of biopolymers to resulting zeta potential of the modified surface was assessed. PC12 cells do not exhibit selective adhesion in the presence of foetal bovine serum. Polystyrene with adsorbed polyornithine promotes primary adhesion of PC12 cells cultured in serum-free medium with nerve growth factor. Subsequently adsorbed laminin induces spreading and differentiation of the cells into neuronal direction. Primary neurons isolated from rat spinal ganglion adhere preferentially on the polyornithine-modified surface. On the polyornithine-laminin surface neurons intensively form neuritis that correlates with proliferation of glial cells positive for S100 protein. The results show that PC12 cells and primary neurons exhibit similar response to surface material with the latter cells being more sensitive to this factor. Isolated cell culture can be used to study the relationship between neurite outgrowth and Schwann cells proliferation on different biomaterials

Phase transition and anomalous electronic behavior in layered dichalcogenide CuS (covellite) probed by NQR

Nuclear quadrupole resonance (NQR) on copper nuclei has been applied for studies of the electronic properties of quasi-two-dimensional low-temperature superconductor CuS (covellite) in the temperature region between 1.47 and 290 K. Two NQR signals corresponding to two non-equivalent sites of copper in the structure, Cu(1) and Cu(2), has been found. The temperature dependences of copper quadrupole frequencies, line-widths and spin-lattice relaxation rates, which so far had never been investigated so precisely for this material, altogether demonstrate the structural phase transition near 55 K, which accompanies transformations of electronic spectrum not typical for simple metals. The analysis of NQR results and their comparison with literature data show that the valence of copper ions at both sites is intermediate in character between monovalent and divalent states with the dominant of the former. It has been found that there is a strong hybridization of Cu(1) and Cu(2) conduction bands at low temperatures, indicating that the charge delocalization between these ions takes place even in 2D regime. Based on our data, the occurrence of energy gap, charge fluctuations and charge-density waves, as well as the nature of phase transition in CuS are discussed. It is concluded that some physical properties of CuS are similar to those of high-temperature superconductors (HTSC) in normal state.Comment: to be publishe