Simulation of elastic–plastic deformation and fracture of materials at micro-, meso- and macrolevels

Physical Mesomechanics of materials is a new branch of mechanics that focuses attention on a mesovolume of loaded material. It is a macro particle in classical continuum mechanics and its behavior under load is equivalent to the bulk. The structural elements for a particular application requires specific models while the computational techniques have to be developed.These research groups have been studying heterogeneous materials behavior at the mesolevel under different types of loading. Hierarchical models are developed to study deformation and fracture of solids at the micro- meso- and macrolevels. Taken into account are the influence of micro- and mesostructure of loaded material in relation to its macro behavior.This work focuses on unifying the method of approach to be supported by tests and calculations. In particular, deformation and fracture mechanisms at the micro-, meso- and macrolevels are examined for metals and composites.     

Coulomb law and hypercomplex approach to electrodynamics

For a Coulomb-type field of a single point charge, generalized expressions are considered which are obtained on the basis of a hypercomplex generalization of electrodynamics with magnetic charges [1]. Along with the usual electrostatic field, in this approach a single charge can create a magnetic field, provided that the space points around the charge are oriented in a different way than the field source (charge) itself. Aside from vector fields, such a charge can create scalar and pseudoscalar fields, if time flows differently at the field points around the charge than at the location of the charge, or if the charge itself moves with respect to a fixed reference frame. The sources of the dual symmetry of the Maxwell equations are discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 101–104, September, 1990.     

Über die Konstitution der Silicatanionen im Kobaltäthylendiaminsilicat

On the Constitution of Silicate Anions in Cobalt Ethylenediamine Silicate A crystalline and acid-soluble silicate of the composition 1 Co₂O₃ · 6 en · 7.2 SiO₂. 26 H₂O was obtained by the reaction of cobalt ethylenediaminehydroxide solution with tetramethoxysilane. Chemical, kinetic, chromatographic, and x-ray investigations showed that this silicate is an acid double four-ring silicate of the formular [Co(en)₃]₂[H₃Si₈O₂₀] · 16–28 H₂O. The preparation of a cobalt propylenediamine (l,2 and 1,3)-silicate is described.     

Application of Raman scattering to study of anisotropy of molecular ensembles

A general expression is obtained for the Raman scattering intensity in an ensemble of diatomic molecules for an arbitrary geometry of the experiment as a function of the anisotropy of angular distribution of molecular axes. In its derivation, the irreducible representation of the density matrix of molecules was used. It is shown that, in the Raman scattering experiments on the study of the anisotropy of molecular ensembles, a significant contribution to the signal is made, not only by the second-order terms 〈cos²θ〉, but also by the fourth-order terms proportional to 〈cos⁴θ〉, which should be taken into account to correctly interpret the experimental data. Convenient experimental geometries are proposed that allow the anisotropy of a molecular ensemble to be investigated.     

Structured codes improve the Bennett-Brassard-84 quantum key rate

A central goal in information theory and cryptography is finding simple characterizations of optimal communication rates under various restrictions and security requirements. Ideally, the optimal key rate for a quantum key distribution (QKD) protocol would be given by a single-letter formula involving optimization over a single use of an effective channel. We explore the possibility of such a formula for the simplest and most widely used QKD protocol, Bennnett-Brassard-84 with one-way classical postprocessing. We show that a conjectured single-letter formula is false, uncovering a deep ignorance about good private codes and exposing unfortunate complications in the theory of QKD. These complications are not without benefit-with added complexity comes better key rates than previously thought possible. The threshold for secure key generation improves from a bit error rate of 0.124 to 0.129.     

Dependences of Mechanical Properties of Ceramics with Bimodal Pore Size Distribution on the Porosity at Various Scale Levels

Russian Physics Journal - Peculiarities in the dependences of the elastic and strength properties of ceramics with a hierarchically organized pore structure on the porosity are revealed. To exclude...