An estimate for the spectral radius of an operator associated with an equation of neutral type

We obtain new bounds for the spectral radius of the operator (Ax) (t) = a(t)x(t–h) in spaces of functions which are-periodic, almost periodic, and continuous and bounded on the whole axis. The results are used to prove a theorem on the existence of-periodic, bounded, and almost periodic solutions for linear functional-differential equations of neutral type.Translated from Matematicheskie Zametki, Vol. 13, No. 1, pp. 67–78, January, 1973.The authors wish to thank M. A. Krasnosel'skii and V. Sh. Burd for discussion of this paper.     

Study of the dynamic contact interaction of deformable bodies

A new algorithm for solving dynamic contact problems involving deformable bodies is proposed. The algorithm is based on formulation of the boundary conditions for the contact interaction with allowance for Coulomb friction in the form of quasivariational inequalities. The algorithm is numerically stable and satisfies geometric constraints in the a priori unknown contact region and conditions specifying that the normal pressure be nonnegative and that the vectors describing tangential velocity and shear stress during slip be oppositely directed. Results are presented from calculations performed for a contact problem for an elastoplastic body in a two-dimensional formulation. Computer Center, Siberian Division, Russian Academy of Sciences, Krasnoyarsk 660036. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 4, pp. 167–173, July–August, 1998.     

ANALYSIS OF BENDING OF COMPOSITE PLATES WITH ACCOUNT FOR THE DIFFERENCE IN RESISTANCE TO TENSION AND COMPRESSION

Journal of Applied Mechanics and Technical Physics - The finite element method is used to develop a computational algorithm for solving a limited class of problems on the bending of...     

The case of a constant absolute invariant for the Lienard system

A criterion is suggested for defining such properties of the right-hand sides in the Lienard polynomial system that guarantee its first absolute invariant turning to a constant.     

Electronic structure of new iron-based superconductors: From pnictides to chalcogenides and other similar systems

The electronic spectra of new iron-based high-temperature superconductors and a number of other chemically similar compounds have been discussed and compared with the focus on iron chalcogenide K_{1 ? x} Fe_{2 ? y} Se₂ and isostructural pnictide BaFe₂As₂ (122). It has been shown that the Fermi surfaces in K_{1 ? x} Fe_{2 ? y} Se₂ are significantly different from those in pnictides. The LDA + DMFT and LDA’ + DMFT calculations have demonstrated that the effect of electron correlations in K_{1 ? x} Fe_{2 ? y} Se₂ on the electronic structure is much stronger than that in the most studied 122 system. The electronic structure of several multiband superconductors similar in chemical composition to iron-based high-temperature superconductors, but having a relatively low T _c value (such as SrPt₂As₂, APt₃P (A = Sr, Ca, La), and (Sr, Ca)Pd₂As₂), and the non-superconducting compound BaFe₂Se₃ has also been discussed. It has been shown that the electronic structure of these systems is significantly different from previously studied iron pnictides and chalcogenides. The T _c value in these systems can be understood within the simple Bardeen-Cooper-Schrieffer model.