Narrow Results

In this paper, we discuss the effects of the topology of a disclination on quantum revivals when a quantum particle is subject to an infinite cylindrical well and a logarithmic potential. By using the WKB (Wentzel, Kramers and Brillouin) approximation, we obtain the eigenvalues of energy and show that the influence of the topology of the disclination on them gives rise to an Aharonov–Bohm-type effect. Further, we discuss how the topology of a disclination influences the classical periods and the revival times.

In this paper, our principal objective is to investigate the impact of disclination and throat radius of a three-dimensional traversable wormhole on quantum oscillator fields. Specifically, we focus on Perry–Mann-type wormhole with disclination while also considering the influence of rainbow gravity’s. We derive the radial equation of the relativistic Klein–Gordon oscillator within this wormhole background under the effects of gravity’s rainbow and the analytical eigenvalue solution is obtained using the confluent Heun function. In fact, we show that the behavior of the oscillator fields is significantly influenced not only by the presence of disclination and the throat radius but also by the parameter of rainbow gravity’s. We choose various such rainbow functions to present and analyze the eigenvalue solutions of the quantum oscillator fields.

Using the Oseen–Zöcher–Frank theory, in the steady state, I study the distortion energy of a disclination line in nematic liquid crystal in the presence of an external magnetic field. The director field around a disclination line is exactly calculated by minimizing the total free energy. The behavior of total free energy as a function of magnetic field for two kinds of nematic material (positive and negative magnetic anisotropy) are discussed. In the short distance limit, the total free energy per unit length is calculated. In this case, the magnetic dependence of total free energy is discussed.

We investigate energetically favorable configurations of point disclinations in nematic films having a bump geometry. Gradual expansion in the bump width Δ gives rise to a sudden shift in the stable position of the disclinations from the top to the skirt of the bump. The positional shift observed across a threshold Δ^th obeys a power law function of |Δ - Δ^th|, indicating a new class of continuous phase transition that governs the defect configuration in curved nematic films.

The ’t Hooft–Polyakov monopole solution in Yang–Mills theory is given new physical interpretation in the geometric theory of defects. It describes solids with continuous distribution of dislocations and disclinations. The corresponding densities of Burgers and Frank vectors are computed. It means that the ’t Hooft–Polyakov monopole can be seen, probably, in solids.

We use the Chern–Simons action for a $𝕊𝕆(3)$-connection for the description of point disclinations in the geometric theory of defects. The most general spherically symmetric $𝕊𝕆(3)$-connection with zero curvature is found. The corresponding orthogonal spherically symmetric $𝕊𝕆(3)$ matrix and $n$-field are computed. Two examples of point disclinations are described.

We consider an elastic medium with a disclination and investigate the topological effects on the interaction of a spinless electron with radial electric fields through the WKB (Wentzel, Kramers, Brillouin) approximation. We show how the centrifugal term of the radial equation must be modified due to the influence of the topological defect in order that the WKB approximation can be valid. Then, we search for bound states solutions from the interaction of a spinless electron with the electric field produced by this linear distribution of electric charges. In addition, we search for bound states solutions from the interaction of a spinless electron with radial electric field produced by uniform electric charge distribution inside a long non-conductor cylinder.

We analyze the interaction of the induced electric dipole moment of a neutral particle with an electric field in elastic medium with a charged disclination from a semiclassical point of view. We show that the interaction of the induced electric dipole moment of a neutral particle with an electric field can yield an attractive inverse-square potential, where it is influenced by the topology of the disclination. Then, by using the Wentzel, Kramers and Brillouin approximation based on the Langer transformation, we show that the centrifugal term of the radial equation must be modified due to the influence of the topology of the disclination. Besides, we obtain the bound states solutions to the Schrödinger equation.

This paper establishes a theoretical model to explore the coupled effect of grain boundary (GB) sliding deformation and crack tip dislocation emission on the critical stress intensity factor (SIF) for crack growth in ultrafine-grained and nanocrystalline materials (NCMs). The model postulates that the stress concentration near a crack tip initiates GB sliding. It is found that GB sliding leads to the formation of wedge disclination dipole at the triple junctions of grain boundaries. Under the external load and stress fields produced by wedge disclinations, dislocations are emitted from crack tips but will stop at the opposite GBs. The influence of the wedge disclination dipole and the dislocation emitted from crack tip on the critical SIF for crack growth is investigated. The model prediction shows that the critical SIF varies with the decrement of grain size, and that there is a critical grain size corresponding to a minimum value of SIF. Compared with the pure brittle fracture in NCMs at the grain sizes of tens of nanometers, the combined deformation mechanisms can bring an increase of the critical SIF for crack growth.

In this work, interaction problems between a finite-length crack with plane and antiplane crystal defects in the context of couple-stress elasticity are presented. Two alternative yet equivalent approaches for the formulation of crack problems are discussed based on the distributed dislocation technique. To this aim, the stress fields of climb and screw dislocation dipoles are derived within couple-stress theory and new ‘constrained’ rotational defects are introduced to satisfy the boundary conditions of the opening mode problem. Eventually, all interaction problems are described by single or systems of singular integral equations that are solved numerically using appropriate collocation techniques. The obtained results aim to highlight the deviation from classical elasticity solutions and underline the differences in interactions of cracks with single dislocations and dislocation dipoles. In general, it is concluded that the cracked body behaves in a more rigid way when couple-stresses are considered. Also, the stress level is significantly higher than the classical elasticity prediction. Moreover, the configurational forces acting on the defects are evaluated and their dependence on the characteristic material length of couple-stress theory and the distance between the defect and the crack-tip is discussed. This investigation reveals either a strengthening or a weakening effect in the opening mode problem while in the antiplane mode a strengthening effect is always obtained.

Path integration is carried out for the bound states of a particle in the combined field of a wedge disclination and a screw dislocation. The energy spectrum extracted from the Feynman kernel differs from that obtained by solving the Schrödinger equation.

In this paper we investigate the possibility of the analog of a phenomenon like superradiance, that is, amplification of a sound wave by reflection induced by a rotating acoustic black hole in the fluid "draining bathtub" model in the presence of a disclination and analyze the role played by this object in which concerns the amplification or reduction of superradiance with the deficit angle.