A mixed‐FEM formulation for nonlinear incompressible elasticity in the plane

This article deals with an expanded mixed finite element formulation, based on the Hu‐Washizu principle, for a nonlinear incompressible material in the plane. We follow our related previous works and introduce both the stress and the strain tensors as further unknowns, which yields a two‐fold saddle point operator equation as the corresponding variational formulation. A slight generalization of the classical Babu?ka‐Brezzi's theory is applied to prove unique solvability of the continuous and discrete formulations, and to derive the corresponding a priori error analysis. An extension of the well‐known PEERS space is used to define an stable associated Galerkin scheme. Finally, we provide an a posteriori error analysis based on the classical Bank‐Weiser approach. © 2002 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 18: 105–128, 2002     

Fundamental aspects of initiated oxidation of tridecane and polyethylene in solutions

Specific features of the initiated oxidation of polyethylene and its low-molecular-weight analogue tridecane, associated with the occurrence of the process in the short-chain mode, were studied.     

Thermal and dielectric behaviors of poly(vinylidene fluoride-trifluoroethylene) copolymers at the curie transition

The thermal and dielectric behaviors of poly(vinylidene fluoride-trifluoroethylene) copolymers near the ferroelectric-to-paraelectric phase transition are investigated for samples with 20, 25, 30, and 40 mol% trifluoroethylene (TrFE). The data suggest that the transition becomes continuous for a particular composition near 50 mol% TrFE. Experimental data are sensitive to thermal history (kinetics of crystallization, and kinetics and cycling over the structural transition). It is found that several anomalies are present at the structural change, and in particular the 30 mol% TrFE sample shows the most marked anomalies. These phenomena can be attributed to defects, but another possibility would be the existence of an intemediate supplementary phase. Both hypotheses are discussed.     

The Pontryagin Maximum Principle 50 years later

Proceedings of the Steklov Institute of Mathematics -     

Coagulation in lipid- and protein-containing systems

The behavior of real disperse systems with organic impurities was examined under conditions of destabilization by inorganic coagulants. A number of physicochemical methods of analysis and a simulation method were used to identify the character and type of the complexes formed and to calculate their stability constants.     

Electro-optic pulse response of ferroelectric liquid crystals

The electro-optic response of ferroelectric smectic C* liquid crystals has been studied. Anomalous switching behaviour of such materials which possess a negative dielectric anisotropy has been reported. These materials show a minimum in response time at a sufficiently high field. We present results showing the dependency of this minimum upon spontaneous polarisation and the effect of AC bias. Calculations based upon the equation of motion of the director around the cone are presented which describe this effect and its dependence on the relative magnitudes of the spontaneous polarization and dielectric anisotropy of the material. Good agreement with the experimental results is found.