807 research outputs found
A Lagrange multiplier method for a Stokes-Biot fluid-poroelastic structure interaction model
We study a finite element computational model for solving the coupled problem
arising in the interaction between a free fluid and a fluid in a poroelastic
medium. The free fluid is governed by the Stokes equations, while the flow in
the poroelastic medium is modeled using the Biot poroelasticity system.
Equilibrium and kinematic conditions are imposed on the interface. A mixed
Darcy formulation is employed, resulting in continuity of flux condition of
essential type. A Lagrange multiplier method is employed to impose weakly this
condition. A stability and error analysis is performed for the semi-discrete
continuous-in-time and the fully discrete formulations. A series of numerical
experiments is presented to confirm the theoretical convergence rates and to
study the applicability of the method to modeling physical phenomena and the
sensitivity of the model with respect to its parameters
INFLUENCE OF THE EVENTS OF FEBRUARY 1917 ON IDEAS OF LOCAL COMMUNITIES ABOUT THE STATE SYSTEM OF CAUCASUS PEOPLES
The article studies the development of ideas of Caucasus communities as regards their status and position in Russia in 1917. With the reference to memoirs of contemporaries and participants of the events it is claimed that the overthrow of Russian monarchy became, on the one hand, impetus for activity in the regions as political and intellectual elite sought to prepare and form a part of Russian federative state as autonomy. On the other hand, as the Interim government grew weak centrifugal forces intensified. The unity of Transcaucasia and the North Caucasus in their political and social development during February-October 1917 is revealed
A new flare star member candidate in the Pleiades cluster
We present a new flare star, which was discovered during our survey on a
selected field at the edge of the Pleiades cluster. The field was observed in
the period 2007 - 2010 with three different CCD-cameras at the University
Observatory Jena with telescopes from 25 to 90 cm. The flare duration is almost
one hour with an amplitude in the R-band of about 1.08 mag. The location of the
flare star in a color-magnitude diagram is consistent with age and distance of
the Pleiades. In the optical PSF of the flare star there are two 2MASS objects
(unresolved in most images in the optical Jena PSF), so it is not yet known
which one of them is responsible for this flare. The BVRIJHK colors yield
spectral types of M1 and M2 with extinction being A_V=0.231+/-0.024 mag and
A_V=0.266+/-0.020 for those two stars, consistent with the Pleiades cluster.Comment: 8 pages, 7 figure
Structural Theory for Laminated Anisotropic Elastic Shells
A linear theory is formulated for analysis of small deflections of thin shells with arbitrary geometrical configuration and laminated of an arbitrary number of layers of different thicknesses, orientations, and anisotropic elastic coefficients. An accurate shell theory (Vlasov's) is used, and the composite-shell constitutive relation incorporates the anisotropic stretching-bending coupling effects considered by Stavsky. For shells of arbitrary geometry, it is found necessary to introduce a new parameter Fij ≡ ∫h z 3Qijdz in the con stitutive relation. This parameter is zero for homogeneous aniso tropic materials and for anisotropic materials laminated symmetri cally with respect to the middle surface. However, for a two-layer filament-wound shell, this parameter can increase the flexural rigidity by 3%, which is greater than a 2% effect considered in a previous layered-anisotropic cylindrical shell analysis.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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