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1.
V.?F.?Kopiev V.?V.?PalchikovskiyEmail author I.?V.?Belyaev Yu.?V.?Bersenev S.?Yu.?Makashov I.?V.?Khramtsov I.?A.?Korin E.?V.?Sorokin O.?Yu.?Kustov 《Acoustical Physics》2017,63(1):113-124
The acoustic parameters of a new anechoic chamber constructed at Perm National Research Polytechnic University (PNRPU) are presented. This chamber is designed to be used, among other things, for measuring noise from aerodynamic sources. Sound-absorbing wedges lining the walls of the chamber were studied in an interferometer with normal wave incidence. The results are compared to the characteristics of sound-absorbing wedges of existing anechoic facilities. Metrological examination of the acoustic parameters of the PNRPU anechoic chamber demonstrates that free field conditions are established in it, which will make it possible to conduct quantitative acoustic experiments. 相似文献
2.
V. F. Kopiev I. V. Khramtsov M. Yu. Zaytsev E. S. Cherenkova O. Yu. Kustov V. V. Palchikovskiy 《Acoustical Physics》2018,64(4):503-510
A technique for studying the aeroacoustic parameters of vortex rings with various diameters in an anechoic chamber is developed. The motion trajectories of vortex rings produced by a piston generator with nozzles with various exit diameters are studied. Spectral analysis of the noise of vortex rings for various distances from nozzles with various diameters is carried out. For the first time, the dependences of the fundamental radiation frequency on the time of a ring’s motion are obtained in dimensionless form. The data on noise from turbulent vortex rings confirm the conclusion that sound from rings with different diameters and velocities is emitted by the same mechanism. 相似文献
3.
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5.
D. G. Khramtsov 《Algebra and Logic》1995,34(5):311-337
We prove that there exists an algorithm which solves a conjugacy problem for finite subgroups in automorphism and outer automorphism groups of a free group of finite rank. Of independent interest is the construction of an algorithm of decomposing an arbitrary free-by-finite group into a fundamental group of a finite graph of finite groups, with the number of steps evaluated explicitly. In passing, we solve the conjugacy problem for finite subgroups in almost free groups. As a consequence, an algorithm is obtained computing generating sets for a group of fixed points in an arbitrary finite automorphism group of a free group of finite rank.Translated fromAlgebra i Logika, Vol. 34, No. 5, pp. 558–606, September-October, 1995.Supported by the RFFR grant No. 93-011-1508 and by the ISF (International Science Foundation) grant RPC000. 相似文献
6.
D. A. Komarov I. A. Slepneva V. V. Glupov V. V. Khramtsov 《Applied magnetic resonance》2005,28(3-4):411-419
The generation of reactive oxygen species during oxidation of DOPA (3-(3,4-dihydroxyphenyl-DL-alanine) in haemolymph of insects has been studied by electron paramagnetic resonance with spin traps 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide and 1-hydroxy-3-carboxy-pyrrolidine. The data support the formation of DOPA-derived highly reactive intermediates during melanization in haemolymph of insects. The formation of superoxide has not been detected apparently due to reaction of DOPA with superoxide. The rate constant of the latter reaction was estimated ask≈5·105 M?1.c?1. The formation of DOPA-semiquinone in haemolymph has been measured using spin stabilization ofo-semiquinones by Mg2+. The comparative studies in haemolymph of intact insects and insects infected by fungal infection suggest an important role of DOPA-semiquinone production in the immune status of insects. 相似文献
7.
L. Ya. Levitan M. R. Noeva G. I. Khramtsov A. V. Sharko M. I. Fedorov E. P. Zinoréva V. N. Shashaurov L. I. Nutrikina V. I. Vashchuk A. N. Balyaev S. E. Ermatov N. A. Sidorov U. Ziyakhanov V. N. Morenko B. Kurmangaliev E. P. Fesenko L. V. Iogansen O. B. Evdokimov G. E. Shchevelev A. P. Yalovets L. L. Moiseenko V. V. Odintsov G. A. Ivashina V. B. Bolotin V. V. Malov O. B. Butusov L. V. Iogansen L. S. Gutyrya V. A. Komashko Yu. V. Titenko A. I. Anukhin V. I. Popov 《Russian Physics Journal》1977,20(5):695-699
8.
D. G. Khramtsov 《Algebra and Logic》1991,30(5):389-409
Translated from Algebra i Logika, Vol. 30, No. 5, pp. 595–623, September–October, 1991. 相似文献
9.
Yu. I. Glazachev V. V. Khramtsov T. A. Berezina L. B. Volodarsky 《Applied magnetic resonance》1998,15(3-4):407-415
EPR spectral sensitivity of the three biradicals of imidazoline and imidazolidine types to the local concentration of protons (pH) in aqueous solutions has been studied. Significant increase ing-factor (Δg ≈ 0.0002) and decrease in hyperfine interaction constant (ΔaN = 0.8?1.2 G) upon the protonation of atom N-3 of the radical heterocycle were observed. The pH dependence of aN andg- factor is described by conventional titration curve with one or two pK values. The latter case was explained by nonindependent protonation of two monoradical fragments closely located in the biradical structure. EPR spectra of protonated and deprotonated forms of the biradicals have significantly different intensities of “biradical” components, Ib, reflecting changes in spin exchange interaction. It has been found that activation energy of spin exchange, Ea, estimated from temperature dependence of Ib in glycerol/water solution is lower for the biradical conformation with larger Ib. This is in agreement with main contribution of direct collisions of monoradical fragments in spin exchange interaction so larger value of Ib corresponds to the conformation with less spatial restrictions for the motion of monoradical fragments (lower Ea). The potential use of the pH-sensitive biradicals as spin labels is discussed. 相似文献
10.
P. G. Baranov I. V. Il’in E. N. Mokhov A. D. Roenkov V. A. Khramtsov 《Physics of the Solid State》1997,39(1):44-48
The EPR spectra of scandium acceptors and Sc2+(3d) ions are observed in 6H-SiC crystals containing a scandium impurity. The EPR spectra of scandium acceptors are characterized by comparatively small
hyperfine interaction constants, whose values are consistent with the constants for other group III elements in SiC: boron,
aluminum, and gallium acceptors. The EPR spectra of scandium acceptors undergo major changes in the temperature interval 20–30
K. In the low-temperature phase the EPR spectra are characterized by orthorhombic symmetry, whereas the high-temperature phase
has higher axial symmetry. The EPR spectra observed at temperatures above 35 K and ascribed by the authors to Sc2+(3d) ions, or to the A
2− state of scandium, have significantly larger hyperfine structure constants and narrower lines in comparison with the EPR
spectra of scandium acceptors. The parameters of these EPR spectra are close to those of Sc2+(3d) in ionic crystals and ZnS, whereas the parameters of the EPR spectra of scandium acceptors correspond more closely to the
parameters of holes localized at group III atoms, in particular, at scandium atoms in GeO2. It is concluded that in all centers the scandium atoms occupy silicon sites.
Fiz. Tverd. Tela (St. Petersburg) 39, 52–57 (January 1997) 相似文献