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Middle Miocene zeolite-bearing turbidites, Abrămuţ Basin (Pannonian Basin), NW Romania

Bojar A. V., Barbu V., Bojar H. P.

Geological Quarterly

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2012

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Vol. 56, No 2

261-268

EN

Detailed lithostratigraphic data from a borehole in the Abrămuţ Basin, located in the northwestern part of Romania, has revealed the presence of turbiditic deposits containing several layers with tuff/tuffaceous materials in the lower Badenian. The age of these deposits is determined by the presence of the foraminifera Praeorbulina glomerosa and Orbulina suturalis. Detailed quantitative and qualitative X-ray diffraction data (XRD) on 10 different tuff layers situated at depths between 2450 and 2640 m show a mineralogical association comprising analcime, quartz, volcanic glass, smectite, mica, calcite, K-feldspar, glass and minor quantity of chlorite and albite. The presence of analcime suggests that the albite isograd for the interval studied has been never reached and the maximum temperatures have been lower than c. 125degrees C since the early Badenian.

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Some results for the reflection problems in Hilbert spaces

Barbu V., Da Prato G.

Control and Cybernetics

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2008

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Vol. 37, no 4

797-810

EN

This work is concerned with existence and uniqueness of a solution of a stochastic variational inequality on closed convex bounded subsets with nonempty interior and smooth boundary of a Hilbert space H (the reflection problem).

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Existence and uniqueness of solutions to wave equations with nonlinear degenerate damping and source terms

Barbu V., Lasiecka I., Rammaha A.

Control and Cybernetics

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2005

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Vol. 34, no 3

665-687

EN

In this article we focus on the global well-posedness of the differential equation u [...] in Omega x(O, T), where j' denotes the derivative of a C1 convex and real valued function j. The interaction between degenerate damping and a source term constitutes the main challenge of the problem. Problems with non-degenerate damping (k = 0) have been studied in the literature (Georgiev and Todorova, 1994; Levine and Serrin, 1997; Vitillaro, 2003). Thus the degeneracy of monotonicity is the main novelty of this work. Depending on the level of interaction between the source and the damping we characterize the domain of the parameters p, m, k, n (see below) for which one obt ains existence, regularity or finite time blow up of solutions. More specifically, when p [is less than or equal to] m + k global existence of generalized solutions in H1 x L2 is proved. For p > m + k, solutions blow up in a finite time. Higher energy solutions are studied as well. For H2 x H1 initial data we obtain both local and global solutions with the same regularity. Higher energy solutions are also proved to be unique.

4

Control of degenerate differential systems

Barbu V., Favini A.

Control and Cybernetics

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1999

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Vol. 28, no 3

397-420

EN

This work concerns the optimal control of linear degenerate differential equations in Hilbert spaces with convex cost criteria