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231.
V. A. Lebedev V. I. Sal’nikov A. V. Bychkov Yu. P. Savochkin M. V. Kormilitsyn 《Russian Journal of Applied Chemistry》2008,81(11):1947-1952
Possibility of preferential dissolution of uranium or aluminum from U-Al alloys in salt electrolytes was examined by performing thermodynamic calculations and experimentally. 相似文献
232.
The recent results on the oscillatory behaviour during methane and ethane oxidation over metal catalysts, including nickel, cobalt and palladium have been reviewed. The application of thermogravimetric analysis in combination with on-line mass-spectrometry and visual observations of the catalyst surface during oscillations provided the definite proof that the origin of the oscillatory behaviour in all these systems was connected with the periodical oxidation–reduction of a catalyst. The variety of spatial patterns was detected over the Ni and especially over the Co foil. Emphasis has been done on the differences and similarities of the oscillatory behaviour in various reactions over different catalysts. 相似文献
233.
234.
O. P. Yushchenko V. F. Kurshetsov A. P. Filin S. A. Akimenko A. V. Artamonov A. M. Blik V. V. Brekhovskikh V. S. Burtovoy S. V. Donskov A. V. Inyakin A. M. Gorin G. V. Khaustov S. A. Kholodenko V. N. Kolosov A. S. Konstantinov V. M. Leontiev V. A. Lishin M. V. Medynsky Yu. V. Mikhailov V. F. Obraztsov V. A. Polyakov A. V. Popov V. I. Romanovsky V. I. Rykalin A. S. Sadovsky V. D. Samoilenko V. K. Semenov O. V. Stenyakin O. G. Tchikilev V. A. Uvarov V. A. Duk S. N. Filippov E. N. Guschin Yu. G. Kudenko A. A. Khudyakov V. I. Kravtsov A. Yu. Polyarush V. N. Bychkov G. D. Kekelidze V. M. Lysan B. Zh. Zalikhanov 《JETP Letters》2018,107(3):139-142
Recent results from OKA setup concerning form factor studies in Ke3 decay are presented. About 5.25 M events obtained for decays of 17.7 GeV/cK+ are selected for the analysis. The linear and quadratic slopes for the decay form factor f+(t) are measured: λ'+ = 2.95 ± 0.022 ± 0.018 × 10 -2 for the linear slope fit and λ+ = 2.611 ± 0.035 ± 0.028 × 10 -2, λ"+ = 1.91 ± 0.19 ± 0.14 × 10 -3 for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be M V = 891 ± 3 MeV; the parameter of the dispersive parametrization is measured to be Λ+ = 2.458 ± 0.018 × 10-2. 相似文献
235.
A method for determining the shear stress relaxation time and the heat release due to deformation of a material is developed based on the Kolsky technique using a split Hopkinson bar. The method was tested in experimental studies of the rheological and energy characteristics of AMg5 M aluminum alloy in the range of strain rates from 300 to 1500 s?1. The relationship between the relaxation time and the thermal and internal energies of AMg5 M alloy during its shock compression was determined. 相似文献
236.
V’yacheslav Akkerman Mikhail Ivanov Vitaly Bychkov 《Flow, Turbulence and Combustion》2009,82(3):317-337
Turbulence produced by the piston motion in spark-ignition engines is studied by 2D axisymmetric numerical simulations in
the cylindrical geometry as in the theoretical and experimental work by Breuer et al. (Flow Turbul Combust 74:145, 2005). The simulations are based on the Navier–Stokes gas-dynamic equations including viscosity, thermal conduction and non-slip
at the walls. Piston motion is taken into account as a boundary condition. The turbulent flow is investigated for a wide range
of the engine speed, 1,000–4,000 rpm, assuming both zero and non-zero initial turbulence. The turbulent rms-velocity and the
integral length scale are investigated in axial and radial directions. The rms-turbulent velocity is typically an order-of-magnitude
smaller than the piston speed. In the case of zero initial turbulence, the flow at the top-dead-center may be described as
a combination of two large-scale vortex rings of a size determined by the engine geometry. When initial turbulence is strong,
then the integral turbulent length demonstrates self-similar properties in a large range of crank angles. The results obtained
agree with the experimental observations of Breuer et al. (Flow Turbul Combust 74:145, 2005). 相似文献
237.
Acoustic measurements using synchrotron radiation have been performed on glassy GeSe2 up to pressures of 9.6 GPa. A minimum observed in the shear-wave velocity, associated anomalous behavior in Poisson's ratio, and discontinuities in elastic moduli at 4 GPa are indicative of a gradual structural transition in the glass. This is attributed to a network rigidity minimum originating from a competition between two densification mechanisms. At pressures up to 3 GPa, a conversion from edge- to corner-sharing tetrahedra results in a more flexible network. This is contrasted by a gradual increase in coordination number with pressure, which leads to an overall stiffening of the glass. 相似文献
238.
Physical mechanism of ultrafast flame acceleration 总被引:1,自引:0,他引:1
We explain the physical mechanism of ultrafast flame acceleration in obstructed channels used in modern experiments on detonation triggering. It is demonstrated that delayed burning between the obstacles creates a powerful jetflow, driving the acceleration. This mechanism is much stronger than the classical Shelkin scenario of flame acceleration due to nonslip at the channel walls. The mechanism under study is independent of the Reynolds number, with turbulence playing only a supplementary role. The flame front accelerates exponentially; the analytical formula for the growth rate is obtained. The theory is validated by extensive direct numerical simulations and comparison to previous experiments. 相似文献
239.
The reactions of oxidized and reduced 6 wt % NiO/-Al2O3 with H2, CH4, CO2, O2, and their mixtures are studied in flow and pulse regimes using a setup equipped with a differential scanning calorimeter DSC-111 and a system for chromatographic analysis. It is shown that treatment with hydrogen at 700° results in the partial reduction of NiO to Ni. Methane practically does not react with oxidized Ni/-Al2O3 but it does react actively with the reduced catalyst to form H2 and surface carbon. The latter is capable of reacting with lattice oxygen of Ni/-Al2O3 (slowly) and with adsorbed oxygen (rapidly). Carbon dioxide also reacts with surface carbon to form CO (rapidly) and with metallic Ni to yield CO and NiO (slowly). Thus, the main route of methane reforming with carbon dioxide on Ni/-Al2O3 is the dissociative adsorption of CH4 to form surface carbon and H2 and the reaction of this carbon with CO2 resulting in the formation of CO by the reverse Boudouard reaction. Side routes are the interaction of the products of methane chemisorption with catalyst oxygen and the dissociative adsorption of CO2 on metallic nickel. A competitive reaction of surface carbon with adsorbed oxygen results in a decrease in the CO2 conversion in methane reforming with carbon dioxide. Therefore, the presence of gaseous oxygen in the reacting mixture decelerates methane reforming (catalyst poisoning by oxygen). 相似文献
240.
Bychkov V 《Physical review letters》2002,89(16):168302
Resonance of a weakly turbulent flame in a high-frequency acoustic wave is obtained. Because of the resonance, an acoustic wave may increase noticeably the amplitude of flame wrinkles, and the respective increase in propagation velocity of the turbulent flame front becomes larger by a factor of 10-20. The effect of resonance is especially important for turbulent flames with realistic thermal expansion propagating in a closed burning chamber, which may account for considerable scattering of experimental results on turbulent flame velocity. 相似文献