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.
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.
We investigate linear and nonlinear modes of parity-time (PT)-symmetric multicore fibers with a twist of peripheral cores with gain and loss around the lossless central core. We determine the ...spectral properties of such a light guiding system and demonstrate that the presence of the lossless central core combined with the fiber twist may significantly change the supermode structure, as well as the PT-symmetry breaking threshold of the multicore fiber with gain and loss. We also construct stationary nonlinear modes of the fiber and verify their stability.
•Determine the spectral properties of twisted multicore fibers with PT-symmetry.•Construct stationary nonlinear modes of the fiber and verify their stability.
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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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.
The space-based GAMMA-400 gamma-ray telescope will measure the fluxes of gamma rays in the energy range from ∼20 MeV to several TeV and cosmic-ray electrons and positrons in the energy range from ...several GeV to several TeV to investigate the origin of gamma-ray sources, sources and propagation of the Galactic cosmic rays and signatures of dark matter. The instrument consists of an anticoincidence system, a converter-tracker (thickness one radiation length, 1
X
0
), a time-of-flight system, an imaging calorimeter (2
X
0
) with tracker, a top shower scintillator detector, an electromagnetic calorimeter from CsI(Tl) crystals (16
X
0
) with four lateral scintillation detectors and a bottom shower scintillator detector. In this paper, the capability of the GAMMA-400 gamma-ray telescope for electron and positron measurements is analyzed. The bulk of cosmic rays are protons, whereas the contribution of the leptonic component to the total flux is ∼10
−3
at high energy. The special methods for Monte Carlo simulations are proposed to distinguish electrons and positrons from proton background in the GAMMA-400 gamma-ray telescope. The contribution to the proton rejection from each detector system of the instrument is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of up to ∼1 × 10
4
.
The potential of the planned GAMMA-400 gamma-ray telescope for detecting subhalos of mass between 10
6
M
⊙
and 10
9
M
⊙
in the Milky Way Galaxy that consist of annihilating dark matter in the form of ...weakly interacting massive particles (WIMPs) is studied. The inner structure of dark matter subhalos and their distribution in the Milky Way Galaxy are obtained on the basis of respective theoretical models. Our present analysis shows that the expected gamma-ray flux from subhalos depends strongly on the WIMP mass and on the subhalo concentration, but that it depends less strongly on the subhalo mass. Optimistically, a flux of 10 to 100 ph per year in the energy range above 100 MeV can be expected from the closest and most massive subhalos, which can therefore be thought to be detectable sources for GAMMA-400. Because of the smallness of fluxes, however, only via a joint analysis of future GAMMA-400 data and data from other telescopes would it become possible to resolve the inner structure of the subhalos. Also, the recent subhalo candidates 3FGL J2212.5+0703 and J1924.8–1034 are considered within our model. Our conclusion is that these sources hardly belong to the subhalo population.
•B-containing coatings have been formed on Mg alloy in one stage.•The full cross section of the interaction of neutrons with samples was determined.•B increases the full cross section of the ...interaction of samples with neutrons.
The work provides the results of the one-step formation of boron-containing coatings on an Mg–Mn–Ce alloy by plasma electrolytic oxidation. The results of studies of the composition, structure and morphology of heteroxide coatings are presented. It was established that the boron is contained in the coating mainly in the form of B or B2O3. The introduction of B changes the color of coatings, and also helps to increase their porosity. The method of determining the full cross section of the interaction of thermal neutrons with samples using the installation of neutron-activation analysis based on 252Cf was developed. It was shown that the introduction of boron into the formed coatings allows to increase the full cross section of the interaction of samples with thermal neutrons by 3.8 times. This effect opens the potential for the use of synthesized material in the field of nuclear technologies and aerospace industry.
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.
The GAMMA-400 currently developing space-based gamma-ray telescope is designed to measure the gamma-ray fluxes in the energy range from ∼20 MeV to several TeV in the highly elliptic orbit (without ...shadowing the telescope by the Earth) continuously for a long time. The physical characteristics of the GAMMA-400 gamma-ray telescope, especially the angular and energy resolutions (at 100-GeV gamma rays they are ∼0.01° and ∼1%, respectively), allow us to consider this space-based experiment as the next step in the development of extraterrestrial high-energy gamma-ray astronomy. In this paper, a method to improve the reconstruction accuracy of incident angle for low-energy gamma rays in the GAMMA-400 space-based gamma-ray telescope is presented. The special analysis of topology of pair-conversion events in thin layers of converter was performed. Applying the energy dependence of multiple Coulomb scattering for pair components, it is possible to estimate the energies for each particle, and to use these energies as weight in the angle reconstruction procedure. To identify the unique track in each projection the imaginary curvature method is applied. It allows us to obtain significantly better angular resolution in comparison with other methods applied in current space-based experiments. When using this method for 50-MeV gamma rays the GAMMA-400 gamma-ray telescope angular resolution is about 4°.
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