Fast EMC Diagnostics of Complex On-Board Radio Systems with Use of Experimentally Refined Worst-Case and Conditionally Worst-Case Models of "Transmitter-to-Receiver" Interactions

An improved computationally efficient technique for EMC diagnostics of radio equipment of complex on-board radio-electronic systems is presented. The first improvement is based on the use of worst-case and conditionally worst-case mathematical models to describe unwanted electromagnetic (EM) interactions between transmitters and receivers of the system, which allows to detect all potentially dangerous interactions rapidly and avoid second-type errors when assessing the danger of these interactions. The second improvement concerns the iterative refinement of worst-case and conditionally worst-case models of potentially dangerous interactions (including models of transmitter radiation spectra, receivers susceptibility characteristics, amplitude-frequency characteristics of decoupling antenna filters and EM spurious couplings between antennas of on-board system) by the use of both numerical simulation methods and measurements to improve the accuracy of EMC diagnostics. The third improvement is associated with the use of an extremely effective technique of discrete nonlinear behavior simulation of radio receivers’ operation in a severe EM environment formed by a set of powerful EM radiations from radio transmitters of the analyzed on-board system and a variety of external EM fields generated by various radio systems of different services

Experimental Estimation of Shielding Effectiveness of Composite Materials by Use of Ultra Wideband Electromagnetic Pulses

A wide set of shielding materials is used for protection of electronic systems and their critical components against the impact of Ultra Wideband Electromagnetic Pulses (UWB EMP). Widely known protection solutions are materials with polymer metalized films, the needle-punched and felt fabrics with conductive fillers, materials with ferromagnetic fillers, fabrics impregnated by electrolyte solutions such as regular water, NaCl and CaCl 2 water solutions. In this paper, a technique for express in-situ measurement of UWB EMP shielding effectiveness of composite materials is developed. The shielding effectiveness of materials with complex structure is tested in framework of the developed technique by the use of Test System providing the generation of EMP with duration of 242±24 ps (at half of maximum) and rise time of 139±14 ps. The obtained value of shielding effectiveness for the EMP with the noted parameters is 15.5 dB for four layers of the needlepunched material with carbon additives impregnated by electrolyte solution, 13.9 dB for the two layers of felt fabric material with a layer of polymer metalized film, and about 12.5 dB for material with the metalized films

Защитные покрытия Ленгмюра–Блоджетт на основе высших жирных кислот

The morphology and tribotechnical properties of Langmuir–Blodgett (LB) monolayers and multilayers of some fatty acids, such as nervonic (NA), cerotic (CA) and montanic acids (OCA), was investigated. It was established that the wear resistance of silicon surface coated by LB monolayer of OCA is greater by 11 and 1.3 times in comparison with the LB monomolecular films of NA and CA, respectively. The multilayer of OCA, formed by 140 layers, increases the stability of steel surface by 35 times.Исследованы морфология и трибологические свойства моно- и мультислойных пленок Ленгмюра– Блоджетт (ЛБ) на основе нервоновой (НК), церотиновой (ЦК) и монтановой кислот (МК). Установлено, что ЛБ монослой МК на поверхности кремния в 11 и 1,3 раза стабильнее мономолекулярных ЛБ пленок НК и ЦК соответственно. Мультислойное покрытие МК, состоящее из 140 слоев, в 35 раз увеличивает износоустойчивость стальной поверхности

Comparative analysis of the Allam cycle and the cycle of compressorless combined cycle gas turbine unit

Nowadays, alternative thermodynamic cycles are actively studied. They allow to remove CO2, formed as a result of fuel combustion, from a cycle without significant energy costs. Calculations have shown that such cycles may meet or exceed the most advanced power plants in terms of heat efficiency. The Allam cycle is recognized as one of the best alternative cycles for the production of electricity. Nevertheless, a cycle of compressorless combined cycle gas turbine (CCGT) unit is seemed more promising for cogeneration of electricity and heat. A comparative analysis of the thermal efficiency of these two cycles was performed. Particular attention was paid to ensuring equal conditions for comparison. The cycle of compressorless CCGT unit was as close as possible to the Allam cycle due to the choice of parameters. The processes, in which the difference remained, were analysed. Thereafter, an analysis of how close the parameters, adopted for comparison, to optimal for the compressorless CCGT unit cycle was made. This analysis showed that these two cycles are quite close only for the production of electricity. The Allam cycle has some superiority but not indisputable. However, if cogeneration of electricity and heat is considered, the thermal efficiency of the cycle of compressorless CCGT unit will be significantly higher. Since it allows to independently regulate a number of parameters, on which the electric power, the ratio of electric and thermal power, the temperature of a working fluid at the turbine inlet depend. Thus, the optimal parameters of the thermodynamic cycle can be obtained in a wide range of operating modes of the unit with different ratios of thermal and eclectic powers. Therefore, the compressorless CCGT unit can significantly surpass the best steam turbine and combined cycle gas turbine plants in district heating system in terms of thermal efficiency. © The Authors, published by EDP Sciences, 2020

Potential advantages of using compressorless combined cycles in power engineering

Attention of humanity is being increasingly focused on prevention of anthropogenic emissions of greenhouse gases, including CO2 [1]. One of the main contributions to CO2 emissions is associated with the production of electric and thermal energy. Despite great efforts, aimed at developing renewable energy technologies, fossil fuels will dominate in this area of human activity for a very long time. Therefore, the capture of CO2, formed during the combustion of fossil fuels, is of particular importance. If air is used as a fuel oxidizer, the combustion products consist of more than 70% nitrogen. It is very difficult and expensive to separate carbon dioxide from this nitrogen. Promising solutions for carbon capture are associated with air separation and fuel combustion in pure oxygen. Recently, considerable attention has been paid to such cycles [2-4]. The gases temperature of a combustor chamber exit is regulated by the supply of CO2 and H2O to a combustion zone. In this case, a spent working fluid is almost entirely composed of a mixture of carbon dioxide and water vapor, which is easily divided into water and pure carbon dioxide. One of the options for such solutions involves a pressure increase for all components of the working fluid before injection them into a combustion chamber in a liquid phase by pumping equipment [5]. Thermodynamic cycles, in which a pressure of the working fluid is increased in the liquid phase by pumping equipment (without a compressor), can be called compressorless. © The Authors, published by EDP Sciences, 2020