排序方式: 共有26条查询结果,搜索用时 15 毫秒
1.
Nonlinear Dynamics - In this paper, we analyze the effect which the choice of a friction model has on tippe top inversion in the case where the resulting action of all dissipative forces is... 相似文献
2.
R. G. Valeev A. N. Deev F. Z. Gilmutdinov S. G. Bystrov O. I. Pivovarova É. A. Romanov V. V. Kriventsov M. R. Sharafutdinov A. A. Eliseev 《Journal of Structural Chemistry》2008,49(1):124-128
This paper presents the results of our study of the structural state and local atomic structure of zinc selenide films obtained by thermal evaporation in supervacuum at condensation temperatures of ?150°C, 0, and 150°C. Structure-sensitive methods such as X-ray diffraction, atomic force microscopy, and EXAFS spectroscopy were used. The parameters of the local atomic environment (interatomic distances, coordination numbers) of zinc and selenium atoms were obtained by Fourier transformation. 相似文献
3.
E. N. Korytkova L. N. Pivovarova O. E. Semenova I. A. Drozdova V. F. Povinich V. V. Gusarov 《Russian Journal of Inorganic Chemistry》2007,52(3):338-344
Magnesium iron hydrosilicate nanotubes with a chrysotile ((Mg,Fe)3Si2O5(OH)4) structure have been synthesized hydrothermally at t = 250–450°C and p = 30–100 MPa. In the hydrothermal synthesis of (Mg,Fe)3Si2O5(OH)4 chrysotile, part of the Fe2+ ions oxidize to Fe3+ and are incorporated into the octahedron and tetrahedron layers of the chrysotile structure. The limiting iron content of chrysotile has been determined up to which cylindrically rolled layers can form to yield nanotubes. The hydrothermal treatment of precursors richer in FeO yields platelike hydrosilicates. The iron ions present in the starting components affect the synthesis parameters, morphology, size, optical properties, and thermal stability of the nanotubes. 相似文献
4.
V. V. Bakovets L. N. Trushnikova I. V. Korol’kov V. V. Sokolov I. P. Dolgovesova T. D. Pivovarova 《Russian Journal of General Chemistry》2009,79(3):356-361
The process of formation of nickel oxide nanostructured powders by annealing nickel hydroxide in the temperature range 200–700°C was studied. Nickel hydroxide was prepared by precipitation with alkali from nickel nitrate solutions. The annealing process was shown to be multi-step. In the first stage the hydrogel Ni (OH)2·nH2O decomposes and partial dehydration of hydroxide occurs. Sizes of the formed particles decrease. At the temperatures above 230°C, further hydrogel decomposition and coalescence of NiO particles proceed. In view of the structural rearrangement of powder at the high temperatures 400–700°C, dehydration process is monitored by the decrease of NiO particles surface area at their coalescence. According to the change in the dehydration mechanism, the hierarchically nanostructured material forms, whose particle sizes are in the range 4–5, 9–12, and 18–40 nm. 相似文献
5.
6.
In the paper, a study of rolling of a dynamically asymmetrical unbalanced ball (Chaplygin top) on a horizontal plane under the action of periodic gyrostatic moment is carried out. The problem is considered in the framework of the model of a rubber body, i.e., under the assumption that there is no slipping and spinning at the point of contact. It is shown that, for certain values of the parameters of the system and certain dependence of the gyrostatic moment on time, an acceleration of the system, i.e., an unbounded growth of the energy of the system, is observed. Investigations of the dependence of the presence of acceleration on the parameters of the system and on the initial conditions are carried out. On the basis of the investigations of the dynamics of the frozen system, a conjecture concerning the general mechanism of acceleration at the expense to periodic impacts in nonholonomic systems is expressed. 相似文献
7.
In this paper we consider the control of a dynamically asymmetric balanced ball on a plane in the case of slipping at the contact point. Necessary conditions under which a control is possible are obtained. Specific algorithms of control along a given trajectory are constructed. 相似文献
8.
V. V. Bakovets L. N. Trushnikova I. V. Korol’kov P. E. Plyusnin I. P. Dolgovesova T. D. Pivovarova N. I. Alferova 《Russian Journal of General Chemistry》2013,83(1):1-9
The sol-gel method of the formation of the nanostructured luminophor based on Y2O3 doped by Eu3+ and Bi3+ was studied. The mechanism of the dehydration and dehydroxylation of gels and xerogels of the mixed hydroxides, particle sizes, structure, and luminescent properties of the synthesized products based on Y2O3 depend on the chemical nature of a precipitating agent (NaOH or NH4OH) and a washing agent (water and alcohol). 相似文献
9.
V. S. Miroshnichenko E. B. Senkevich A. G. Pivovarova D. V. Yudintsev 《Radiophysics and Quantum Electronics》2010,53(3):182-190
We present the results of studying theoretically and experimentally the peculiarities of mode excitation in a generator of
diffraction radiation with the two- and three-cascade interaction space in one open resonator. To describe the multistage
interaction mechanism, the theoretical model used considers the excitation of the TEM0nq modes, which have n in-phase field “spots,” i.e., cascades, along the direction of the electron beam motion. It is shown
that even the use of the two-cascade interaction space with the TEM01q modes allows one to reduce the starting current of the generator by 1.91 times. The results of studying experimentally the
two-cascade generator in the 5 and 1.5-mm wavelength ranges are presented. The in-phase property of the electron beam with
the resonance field was achieved by disrupting the periodicity of the lattice slots at the center of the interaction space.
The output power of the two-stage generator of 5-mm diffraction radiation in the TEM013 mode ranged from 3 to 5 W. We also
observed a 4–5-fold increase in the starting current for the regime of surface waves. 相似文献
10.
A. P. Pivovarova O. P. Shustrova O. V. Mel'nikova 《Journal of Applied Spectroscopy》2002,69(4):642-645
By means of vibrational spectroscopy and crystal optic analysis, the symmetry of crystals with the structure of fersmite in the Li0.5Ln0.5Nb2O6 series, where Ln = Nd—Lu and Y, has been refined. 相似文献