4,269 research outputs found

    Determination of Residual Stresses in the Products with Floating

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    The paper presents the results of the application of the acoustic method for estimating residual stresses in products with surfacing (steel 15H2MFA with austenitic surfacing). The possibility of using this technique on real, particularly responsible constructions is analyzed, without affecting their performance. Keywords: ultrasonic testing, residual stresses, austenitic surfacing, 15H2MFA

    Measurement of light mesons at RHIC by the PHENIX experiment

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    The PHENIX experiment at RHIC has measured a variety of light neutral mesons (π0\pi^{0}, KS0_{S}^{0}, η\eta, ω\omega, η\eta^{\prime}, ϕ\phi) via multi-particle decay channels over a wide range of transverse momentum. A review of the recent results on the production rates of light mesons in p+p and their nuclear modification factors in d+Au, Cu+Cu and Au+Au collisions at different energies is presented.Comment: 5 pages, 4 figures, talk given at Hard Probes 2008 conference in La Toja, Spain. submitted to EPJ

    Fractal growth of rotating DLA-clusters

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    Terahertz control in a transmission electron microscope

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    Ultrafast electron microscopy provides a movie-like access to structural dynamics of materials in space and time, but fundamental atomic motions or electron dynamics are, so far, too quick to be resolved. Here we report the all-optical control, compression and characterization of electron pulses in a transmission electron microscope by the single optical cycles of laser-generated terahertz light. This concept provides isolated electron pulses and merges the spatial resolution of a transmission electron microscope with the temporal resolution that is offered by a single cycle of laser light. Central to these achievements is a perforated parallel-plate metallic waveguide in which transverse velocity mismatch and magnetic forces are mitigated by electrically constructive and magnetically destructive interferences of incoming and reflected terahertz half-cycles from a displaced waveguide termination. Measurements of spatial chirp via energy-filtered imaging reveal flat pulses with no transversal deflection or temporal aberrations at the specimen. We also report the all-optical control of multi-electron states and discover a substantial two-electron and three-electron anti-correlation in the time domain. These results open up the possibility to visualize atomic and electronic motions together with their quantum correlations on fundamental dimensions in space and time

    Cold Flow Model Study on Interconnected Fluidized Bed Reactors for Multi-generation Systems and Chemical Looping Processes

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    Interconnected fluidized bed reactors (DCFB) were implemented in multi-generation systems (pyrolysis FB reactor and CFB boiler), chemical looping combustion (CLC) systems (double metal oxides or carbonate oxide reactors) and three reactor chemical looping gasification processes. The presented data focus on the solids circulation rate and on pressure profiles of the DCFB depended on selected operating parameters such as fluidization gas flow rate, loop seal fluidization, and solids inventory. Most work was devoted to studying standpipe and valve operation

    The "Horizon-T" Experiment: Extensive Air Showers Detection

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    Horizon-T is an innovative detector system constructed to study Extensive Air Showers (EAS) in the energy range above 10^16 eV coming from a wide range of zenith angles (0 - 85 degrees). The system is located at Tien Shan high-altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level. It consists of eight charged particle detection points separated by the distance up to one kilometer as well as optical detector subsystem to view the Vavilov-Cerenkov light from the EAS. The time resolution of charged particles and Vavilov-Cerenkov light photons passage of the detector system is a few ns. This level of resolution allows conducting research of atmospheric development of individual EAS.Comment: Initial technical note for Horizon-T experiment, updated with recent detector upgrades, 11/2016. Updated 12/2017 with minor edits. Large upgrade will be in another articl

    Specific Features of Solid Fuels Combustion in Oxygen Atmosphere with Recirculation of CO2

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    Aspects of coal combustion have been experimentally studied under oxyfuel conditions, one of the promising technologies for carbon capture and storage (CCS). Here, the thermogravimetric analysis (TGA) method was chosen as an experimental technique. Coal pyrolysis tests performed under an O2/CO2 atmosphere were compared with a conventional O2/N2 environment in terms of reaction rate and total volatile yield. Combustion of the resulting chars in the corresponding atmospheres revealed somewhat different combustion rates with a less vigorous reaction in the O2/CO2 medium. The two manipulated factors – namely, the inherently different char reactivities due to the different atmospheres they were obtained in and the different atmospheres of the actual combustion process – were distinguished by performing another series of tests with chars pyrolysed under identical conditions using a standard routine. These chars also showed a weaker reaction in O2/CO2 atmosphere, which was attributed to the lower binary diffusion coefficient of the O2/CO2 pair. The activity of the char – CO2 gasification reaction in an O2/CO2 environment was also investigated and revealed some contribution of this reaction to the conversion process. This was particularly noticeable at temperatures above 750 °C and under an internal diffusional controlled regime (zone II), implying displacement of oxygen out of the char particle pore volume, which allowed free reaction of CO2 on the developed pore surface. Non-isothermal kinetic analysis of the intrinsic kinetics of the oxidation reaction in O2/CO2 revealed no particular difference compared to the O2/N2 medium, at least when the char-CO2 reaction was inhibited. The obtained data were used to develop a coal combustion model under O2/CO2 conditions, which was then incorporated as a combustion module into circulating fluidized bed (CFB) computation software
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