Dislocation substructures and internal stress fields in bulk- and differentially quenched rails

A layer-by-layer analysis of rails bulk-hardened in oil and differentially hardened in a variety of regimes is performed by means of transmission electron microscopy. Quantitative parameters of dislocation substructures and internal stress fields, and their dependences on the distance from the tread contact surface are established. It is shown that the most dangerous stress concentrators are interfaces between globular cementite matrix particles; such interfaces form predominantly in rails subjected to bulk quenching.     

Investigating iron-oxygen nanostructures on silicon

Iron-oxygen (Fe-O) groups are synthesized on the surface of single-crystal silicon by means of molecular layering. The controlled reduction of these groups is performed in a hydrogen flow. The magnetic properties of the synthesized structures and their phase composition are investigated via nuclear gamma-resonance spectroscopy. It is shown that the chosen conditions of reduction allow us to perform the controlled transformation of synthesized iron-oxygen nanostructures into magnetically ordered phases Fe₃O₄ and α-Fe.     

Resonance magnetoplasticity in the EPR scheme under ultralow magnetic fields

Resonance relaxation displacements of dislocations in NaCl crystals exposed to crossed ultralow magnetic fields (static field B = 26–261 μT and radiofrequency field B ～ 3 μT) in the electron paramagnetic resonance scheme are studied. The effect is also observed in the magnetic field of the Earth when crossed with a pulsed pump field with a resonance duration of ～0.5 μs. Changes in the microhardness of crystals of ZnO, triglycine sulfate, and potassium hydrogen phthalate after their exposure to the magnetic field of the Earth and the orthogonally directed pump field are found out.     

Investigation of the lithium-nitrogen melt microstructure by neutron diffraction

The microstructure of Li-N melts with nitrogen impurity contents of 1.3 and 3.5 at % has been investigated by neutron diffraction. The main microstructural characteristic of the material (total structure factor) and the partial structure factors of the melt components and the radial distribution functions of particles have been obtained. It is established that there is no prepeak in the structure factor of Li-N melts, which indicates the existence of clusters of a certain size in the melt. Analysis of the partial structural characteristics suggests the existence of nitrogen impurity in Li-N melts in the form of lithium nitride Li₃N.     

Cartan’s Structure Theory of Symmetry Pseudo-Groups, Coverings and Multi-Valued Solutions for the Khokhlov–Zabolotskaya Equation

We derive two non-equivalent coverings for the modified Khokhlov–Zabolotskaya equation from Maurer–Cartan forms of its symmetry pseudo-group. Also we find Bäcklund transformations between the obtained covering equations. We apply these results to constructing multi-valued solutions for the Khokhlov–Zabolotskaya equation.     

Chessboard-like buckling modes of compressed materials

A transversally isotropic uniform elastic medium is considered during uniform compression in the isotropy plane. Under definite assumptions on the elasticity moduli of the material, it is established that the buckling mode during the postcritical compression has a stable chessboard-like character.     

Improvement of Wave Packet Molecular Dynamics Using Packet Splitting

The method of Wave Packet Molecular Dynamics Method (WPMD) is a promising replacement of the classical molecular dynamics for the simulations of many‐electron systems including nonideal plasmas. In this contribution we report on a packet splitting technique where an electron is represented by multiple Gaussians, with mixing coefficients playing the role of additional dynamic variables. It provides larger flexibility and better accuracy than the original WPMD with a single Gaussian per electron. As a test case we consider ionization of hydrogen atom in a short laser pulse, where the split packets provide a basis for quantum branching (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stability loss in an infinite plate with a circular inclusion under uniaxial tension

Loss of stability under uniaxial tension in an infinite plate with a circular inclusion made of another material is analyzed. The influence exerted by the elastic modulus of the inclusion on the critical load is examined. The minimum eigenvalue corresponding to the first critical load is found by applying the variational principle. The computations are performed in Maple and are compared with results obtained with the finite element method in ANSYS 13.1. The computations show that the instability modes are different when the inclusion is softer than the plate and when the inclusion is stiffer than the plate. As the Young’s modulus of the inclusion approaches that of the plate, the critical load increases substantially. When these moduli coincide, stability loss is not possible.