2,206 research outputs found
Theoretical Prerequisites for the Creation of a Dynamic Model of the Process of Displacement of the Earth's Surface
Discourse in virtual cross-cultural communication: a dialogue of cultures or a clash of mentalities? (A case study research in EFL education in Russia)
This paper presents a case study research based on the experience of Moscow State University of using cross-cultural telecommunication projects as a "testing ground" for developing students' cross-cultural communicative competence. This competence was assessed in terms of success / failure of cross-cultural interaction. The transcripts of forums and chats have been analyzed as well as the results of the survey of students-participants, aimed at getting their opinion about the project ("student satisfaction" factor)
Wave turbulence in the two-layer ocean model
This paper looks at the two-layer ocean model from a wave turbulence
perspective. A symmetric form of the two-layer kinetic equation for Rossby
waves is derived using canonical variables, allowing the turbulent cascade of
energy between the barotropic and baroclinic modes to be studied. It turns out
that energy is transferred via local triad interactions from the large-scale
baroclinic modes to the baroclinic and barotropic modes at the Rossby
deformation scale. From there it is then transferred to the large-scale
barotropic modes via a nonlocal inverse transfer. Using scale separation a sys-
tem of coupled equations were obtained for the small-scale baroclinic component
and the large-scale barotropic component. Since the total energy of the
small-scale component is not conserved, but the total barotropic plus
baroclinic energy is conserved, the baroclinic energy loss at small scales will
be compensated by the growth of the barotropic energy at large scales. It is
found that this transfer is mostly anisotropic and mostly to the zonal
component
Large-scale drift and Rossby wave turbulence
We study drift/Rossby wave turbulence described by the large-scale limit of the Charney–Hasegawa–Mima equation. We define the zonal and meridional regions as and respectively, where is in a plane perpendicular to the magnetic field such that k x is along the isopycnals and k y is along the plasma density gradient. We prove that the only types of resonant triads allowed are and . Therefore, if the spectrum of weak large-scale drift/Rossby turbulence is initially in Z it will remain in Z indefinitely. We present a generalised Fjørtoft's argument to find transfer directions for the quadratic invariants in the two-dimensional -space. Using direct numerical simulations, we test and confirm our theoretical predictions for weak large-scale drift/Rossby turbulence, and establish qualitative differences with cases when turbulence is strong. We demonstrate that the qualitative features of the large-scale limit survive when the typical turbulent scale is only moderately greater than the Larmor/Rossby radius
Quadratic invariants for discrete clusters of weakly interacting waves
We consider discrete clusters of quasi-resonant triads arising from a Hamiltonian three-wave equation. A cluster consists of N modes forming a total of M connected triads. We investigate the problem of constructing a functionally independent set of quadratic constants of motion. We show that this problem is equivalent to an underlying basic linear problem, consisting of finding the null space of a rectangular M × N matrix with entries 1, −1 and 0. In particular, we prove that the number of independent quadratic invariants is equal to J ≡ N − M* ≥ N − M, where M* is the number of linearly independent rows in Thus, the problem of finding all independent quadratic invariants is reduced to a linear algebra problem in the Hamiltonian case. We establish that the properties of the quadratic invariants (e.g., locality) are related to the topological properties of the clusters (e.g., types of linkage). To do so, we formulate an algorithm for decomposing large clusters into smaller ones and show how various invariants are related to certain parts of a cluster, including the basic structures leading to M* < M. We illustrate our findings by presenting examples from the Charney–Hasegawa–Mima wave model, and by showing a classification of small (up to three-triad) clusters
The energy cascade of surface wave turbulence: toward identifying the active wave coupling
We investigate experimentally turbulence of surface gravity waves in the
Coriolis facility in Grenoble by using both high sensitivity local probes and a
time and space resolved stereoscopic reconstruction of the water surface. We
show that the water deformation is made of the superposition of weakly
nonlinear waves following the linear dispersion relation and of bound waves
resulting from non resonant triadic interaction. Although the theory predicts a
4-wave resonant coupling supporting the presence of an inverse cascade of wave
action, we do not observe such inverse cascade. We investigate 4-wave coupling
by computing the tricoherence i.e. 4-wave correlations. We observed very weak
values of the tricoherence at the frequencies excited on the linear dispersion
relation that are consistent with the hypothesis of weak coupling underlying
the weak turbulence theory.Comment: proceedings of the Euromech-Ercoftac workshop "Turbulent Cascades II"
organized in Ecole Centrale de Lyon in december 201
Direction of improvement of the motivation system of railway transport personnel in the conditions of crisis
Запропоновано удосконалення проведення атестації персоналу залізничного транспорту як шлях до більш справедливого та об’єктивного їх оцінювання з метою удосконалення мотивації до праці.The article offers improvement of certification of railway staff as a way to more just and objective evaluation with the aim of improving motivation to work
Superconductivity in the Cuprates as a Consequence of Antiferromagnetism and a Large Hole Density of States
We briefly review a theory for the cuprates that has been recently proposed
based on the movement and interaction of holes in antiferromagnetic (AF)
backgrounds. A robust peak in the hole density of states (DOS) is crucial to
produce a large critical temperature once a source of hole attraction is
identified. The predictions of this scenario are compared with experiments. The
stability of the calculations after modifying some of the original assumptions
is addressed. We find that if the dispersion is changed from an
antiferromagnetic band at half-filling to a tight binding
narrow band at , the main conclusions of the approach remain
basically the same i.e. superconductivity appears in the -channel and is enhanced by a large DOS. The main features
distinguishing these ideas from more standard theories based on
antiferromagnetic correlations are here discussed.Comment: RevTex, 7 pages, 5 figures are available on reques
Resonant X-ray diffraction studies on the charge ordering in magnetite
Here we show that the low temperature phase of magnetite is associated with
an effective, although fractional, ordering of the charge. Evidence and a
quantitative evaluation of the atomic charges are achieved by using resonant
x-ray diffraction (RXD) experiments whose results are further analyzed with the
help of ab initio calculations of the scattering factors involved. By
confirming the results obtained from X-ray crystallography we have shown that
RXD is able to probe quantitatively the electronic structure in very complex
oxides, whose importance covers a wide domain of applications.Comment: 4 pages 4 figures, accepted for publication in PR
- …