The causes of acoustic noise occurring during braking of electric vehicles, in particular, in the metro, were analyzed. The spectrum of such noise was measured, and it is shown that high-frequency ...discrete tones are excited by braking resistors, applied for electrodynamic braking of electric vehicles. Three proposed mechanisms of electromechanical interaction in a Fecral plate, which is a braking resistor element, were considered: the Ampère force and linear and nonlinear magnetostriction. It was shown that predominant odd harmonics indicate the presence of a significant piezomagnetic effect and the inverse effect of linear magnetostriction in the Fecral alloy. A phenomenological approach was used to calculate the piezomagnetic tensor elements for Fecral. Calculations by the finite element method showed that asymmetric cuts introduced into the plate may significantly decrease intensity of acoustic vibrations excited by the braking resistor.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
As a consequence of the development of deep oil refining in the Russian Federation, an urgent search is underway for rational uses for petroleum coke in the power industry. For operating pulverized ...coal boilers of thermal power plants (TPPs), petroleum coke is an extremely undesirable fuel due to its low reactivity and high vanadium and sulfur content, which makes it very difficult to ensure regulatory emissions and prevent intense corrosion of heating surfaces. Based on accumulated experimental and analytical work, it is recommended to use combined-cycle plants with integrated hearth gasification of coke. In the article, a number of comparative characteristics of the hearth gasification of petroleum coke are presented. The possibility of rapidly implementing pilot integrated gasification combined cycle (IGCC) units for petroleum coke gasification is considered as a means of permitting the effective modernization of obsolete coal-fired power plants in the Russian Federation. Considerations are expressed about the nature of priority work in the Russian Federation on the decarbonization of energy industries, which is currently being aggressively promoted in Western countries.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A modulated pseudo-Hermitian optical dimer is investigated. The parameter ranges are determined where the eigenmodes of the dimer conserve their power. It is shown that such a dimer has several ...exceptional points, and it is found that the dimer modes can conserve their average power over the period even if each of its segments is in the PT-broken phase. On the other hand, even if each segment is in the PT symmetric phase, the average power over the period is not conserved for the dimer. Thisspecial feature is determined by the relationship between the dimer length and the beat period of the signal in the individual segments of the dimer.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Integrated gasification combined-cycle (IGCC) units, which use solid fuels (coal, petroleum coke, etc.) for combined-cycle power generation, have been under development for approximately half a ...century. At present, the countries of the Asian region show the greatest interest in this type of power plants. Two large IGCC power units entered into commercial operation at Nakoso and Hirono thermal power plants (TPPs) in Japan; in addition, the Osaki CoolGen project is advancing greatly. The People’s Republic of China and the Republic of Korea are also improving their IGCC projects. Development of more efficient technologies for generator gas cleaning and application of the next generation of gas-turbine units (GTUs) at new IGCC units have cut down harmful emissions and increased the efficiency up to 48%. The 21st century has brought increased interest in IGCC units due to the ability of their equipment to capture CO
2
. Besides the above-mentioned advantages, IGCC units also have disadvantages, the biggest of which is their high cost. That is why, despite many IGCC projects to be deployed in the 2000s, most of these projects were subsequently canceled, and the plants built in the 1990s are being gradually decommissioned. The promising direction for future application of IGCC units is the production of hydrogen for fuel cells with simultaneous CO
2
capture. The polygeneration technology already used at some facilities, which enable the generation and delivery to the consumer of not only electricity but also gasification by-products, will also render support to the solution of the economic problems of IGCC units.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The method of plasma electrolytic oxidation (PEO) for modifying surface of magnesium alloys is increasingly being used in many areas of industry and medicine. In this paper, the influence of the ...parameters of PEO process on the formation of coatings in potentiodynamic modes was investigated. The morphology and corrosion properties of PEO coatings were studied by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffractometry, and electrochemical techniques. It was shown that in the potentiodynamic mode, properties of coatings can be controlled by the maximum formation current density. The influence of a surface area of treated sample on the PEO process and coatings' properties was studied.
It was shown that an increase in voltage limit increases the formation current density of PEO process, which leads to an increase in the thickness and porosity of the coatings. It was found that the rate of voltage's change did not affect the change in the formation current densities; however, it significantly affected the thickness of the formed layer. It was established that a large coating's thickness and a small number of pores are not an indicator of high corrosion resistance, the pores size is more significant. The results of this study allow to adjust various surface properties by modifying coating formation mode.
•The PEO process proceeds in 5 stages of the growth of the oxide layer.•The current density does not depend on the rate of voltage change during oxidation.•Optimizing the PEO mode, a controlled change in morphology and properties is achieved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Bu
4
NI/
t-
BuOOH oxidative system is widely used in organic synthesis, but mechanistic principles underlying its reactivity are only partially explored. In this work, drawing on the example of ...the oxidative C–O coupling reaction between compounds with a carbonyl group and (or) a benzyl moiety with
N
-hydroxyphthalimide, it has been discovered that the coupling with the CH-acidic fragment of the carbonyl group proceeds
via
ionic mechanism, and the coupling with the benzyl fragment proceeds
via
radical mechanism. When dimethylacetamide is used as a solvent, the ionic process with the participation of the carbonyl group prevails, while in MeCN the radical process involving the benzyl moiety is realized along with the ionic process. For the oxidative C–O coupling with participation of the benzyl moiety without affecting the α-CH fragment of the carbonyl group, it is advisable to use PhI(OAc)
2
, Ce(NH
4
)
2
(NO
2
)
6
, or
t‑
BuOO
t-
Bu as oxidants for which only radical pathway is characteristic.
—
A prototype of the electromagnetic calorimeter for the GAMMA-400 γ-ray telescope has been calibrated at the Pakhra S-25R electron synchrotron of the Lebedev Physical Institute. The measured energy ...resolution of the GAMMA-400 calorimeter is consistent with the results of the Monte Carlo simulation. The applicability of the Pakhra S-25R accelerator for calibrating detectors in various experiments has been confirmed.
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The results of the participation of the All-Russia Thermal Engineering Institute in the implementation of systems for plasma-assisted startup of and flame stabilization in the boiler of the Cherepet’ ...TPP are discussed.
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The impact of high-frequency (1.2 MHz) ultrasound with a power density of 0.33 W cm(-2) on microcapsule nanocomposite shells with embedded zinc oxide nanoparticles was investigated by exploring ...modeling simulations and direct visualization. For the first time the sonication effect has been monitored in situ on individual microcapsules upon exposure of their aqueous suspension to ultrasound. The stress distribution on the microcapsule shell for the impact of ultrasound with high (1.2 MHz) and low (20 kHz) frequency at two fixed intensities (0.33 and 30 W cm(-2)) has been modeled. As shown in silico and experimentally the nanocomposite microcapsules were destroyed more effectively by the action of high-frequency (1.2 MHz) ultrasound in comparison to the low frequency (20 kHz) one with the same power density.
The future space-based GAMMA-400
-ray telescope will operate onboard the Russian astrophysical observatory in a highly elliptic orbit during 7 years. Observing
-ray sources from Galactic plane,
-ray ...bursts,
-ray diffuse emission,
rays from the Sun, and
rays from dark matter particles will be performed uninterruptedly for a long time (
100 days) in point-source mode in contrast to scanning mode for Fermi-LAT and other space- and ground-based instruments. GAMMA-400 will measure
rays in the energy range from
20 MeV to several TeV units, have the unprecedented angular (
at
GeV) and energy (
at
GeV) resolutions better than for Fermi-LAT, as well as ground-based
-ray facilities, by a factor of 5–10, and perfectly separate
rays from cosmic-ray background.
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