561 research outputs found
A characterization of the symmetric steady water waves in terms of the underlying flow
In this paper we present a characterization of the symmetric rotational
periodic gravity water waves of finite depth and without stagnation points in
terms of the underlying flow. Namely, we show that such a wave is symmetric and
has a single crest and trough per period if and only if there exists a vertical
line within the fluid domain such that all the fluid particles located on that
line minimize there simultaneously their distance to the fluid bed as they move
about. Our analysis uses the moving plane method, sharp elliptic maximum
principles, and the principle of analytic continuation.Comment: 10 page
On the existence of steady periodic capillary-gravity stratified water waves
We prove the existence of small steady periodic capillary-gravity water waves
for general stratified flows, where we allow for stagnation points in the flow.
We establish the existence of both laminar and non-laminar flow solutions for
the governing equations. This is achieved by using bifurcation theory and
estimates based on the ellipticity of the system, where we regard, in turn, the
mass-flux and surface tension as bifurcation parameters.Comment: 17 pages, to appear in Ann. Scuola Norm. Sup. Pisa Cl. Sc
A gradient flow approach to a thin film approximation of the Muskat problem
A fully coupled system of two second-order parabolic degenerate equations
arising as a thin film approximation to the Muskat problem is interpreted as a
gradient flow for the 2-Wasserstein distance in the space of probability
measures with finite second moment. A variational scheme is then set up and is
the starting point of the construction of weak solutions. The availability of
two Liapunov functionals turns out to be a central tool to obtain the needed
regularity to identify the Euler-Lagrange equation in the variational scheme
THE REFORM OF NATIONAL BANK OF ROMANIA AFTER ACCESSION TO EU: CHALLENGES AND PERSPECTIVES
In January 2007, Romania had become a member of the European Union and the National Bank of Romania a member of The European System of Central Banks (ESCB). This event was a confirmation of the success of Romanian reforms, but, on the other hand, it was a beginning of a new stage in the process of accomplishing the nominal and real convergence conditions, set in the Maastricht Treaty. In this study we have done some considerations about the NBR's reform performances before and after EU accession and, also, we have talked about the main challenges and perspectives for Romanian central bank in the new economic environment imposed by the integration process.European integration, central bank, reform, challenges, perspectives
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