Slit radiator at the edge of an impedance wedge in a uniaxial plasma

A rigorous analytical solution is derived for the problem of the excitation of electromagnetic waves by a magnetic flux source located at the top of a wedge with impedance boundaries. The wedge is placed in a uniaxial anisotropic plasma that has been magnetized transverse to the edge of the wedge direction.Translated from Izvestiya Vysshikh Uchebnikh Zavedenii, Fizika, No. 5, pp. 88–92, May, 1987.     

The scattering of the field of a point source by an axisymmetric screen with a variable impedance

The method of continued boundary conditions is used to solve the acoustic diffraction problem for the case of a field generated by a point source and diffracted by an axisymmetric screen, with generalized impedance boundary conditions being satisfied at the screen surface. Two types of impedance boundary conditions are considered, which differ; at zero impedance one of them takes the form of the Dirichlet boundary condition, while the other the takes the form of the Neumann boundary condition. Both stationary and non-stationary diffraction problems are investigated. Numerical results are obtained for screens with parabolic and spherical shapes.     

点光源劈尖干涉的条纹分布特征

在有限远的点光源照射下,导出了劈尖干涉的明、暗纹条件,通过Matlab软件,用数值分析方法给出了劈尖表面条纹分布特征,讨论了光源距离对表面条纹分布的影响.     

Field due to a point source in a layer over an inhomogenous medium

Summary A point source at an interface between a homogeneous layer of finite depth and an inhomogeneous half-space is considered. The transmitted wave and the dispersion relation for the Love waves is calculated analytically. The authors of this paper have agreed to not receive the proofs for correction.     

Field of a point source in a semi-infinite elastic medium

An exact solution for the tensor Green's function of a harmonic field for a semi-infinite elastic medium is presented in an easy-to-use form in the theory of wave scattering. The solution is derived in the form of a sum of the Green's functions for an infinite medium and the term satisfying the homogeneous wave equation for a semi-infinite elastic medium. The results reproduce the known far-field asymptotics containing longitudinal, transversal and surface Rayleigh-type wave modes. The near-field asymptotic is essentially different for the regions far and near the boundary.     

A local edge of the wedge theorem

A local version of the edge of the wedge theorem is proved. The boundary values are not required to be equal on a whole open neighborhood of the given point, but essentially only along a bunch of lines through this.     

A generalized edge of the wedge theorem

The edge of the wedge theorem is generalized to the case where one only assumes the existence and equality of the distribution boundary values off _±(z) and all their derivatives on some analytic curveC inR ⁿ . Heref _±(z) are holomorphic inR ⁿ ±iC, respectively, whereC is a convex cone, andC has its tangent vector inC at every point. Under these assumptions there exists an analytic continuationf(z) holomorphic in some complex neighbourhood of the double cone generated byC. A proof is also given of the connection between the existence of a distribution boundary value and the growth of the holomorphic function near the boundary.     

Propagation in an elastic wedge using the virtual source technique

The virtual source technique, which is based on the boundary integral method, provides the means to impose boundary conditions on arbitrarily shaped boundaries by replacing them by a collection of sources whose amplitudes are determined from the boundary conditions. In this paper the virtual source technique is used to model propagation of waves in a range-dependent ocean overlying an elastic bottom with arbitrarily shaped ocean-bottom interface. The method is applied to propagation in an elastic Pekeris waveguide, an acoustic wedge, and an elastic wedge. In the case of propagation in an elastic Pekeris waveguide, the results agree very well with those obtained from the wavenumber integral technique, as they do with the solution of the parabolic equation (PE) technique in the case of propagation in an acoustic wedge. The results for propagation in an elastic wedge qualitatively agree with those obtained from an elastic PE solution.     

Three-dimensional problem of diffraction by an ideally conducting wedge with a radio-absorbing cylinder on the edge

Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 31, No. 9, pp. 1074–1081, September, 1988.     

Nematic liquid crystal in the wedge and edge geometry in the case of homeotropic alignment

Nematic liquid crystal confined to a wedge or edge is studied on the assumption that the confining surfaces provide strong and weak homeotropic anchorings, respectively. Both infinite and finite systems are considered. The model based on the Frank-Oseen and Rapini-Papoular formalisms predicts two textures of opposite rotations of the director as in the case of strong anchoring on both surfaces. However, the presence of weak anchoring results in a length scale λ which characterizes the crossover between the regions close to the apex and far from it. The ratio λ/b , where b is the extrapolation length, is a function of the opening angle α. Both stable and metastable textures are considered and the mechanism by which a texture loses its stability is found. It is related to the formation of a defect-like structure at the surface of weak anchoring whose distance from the apex is λ(α) and the loss of stability is signalled by the divergence of λ. Only in the limit α → 2τ, the defect-like structure transforms into a defect of strength -1/2 located at a finite distance from the apex.     

Threshold resummation for the production of a color sextet (antitriplet) scalar at the LHC

This paper is devoted to the study of warm inflation using vector fields in the background of a locally rotationally symmetric Bianchi type I model of the universe. We formulate the field equations, and slow-roll and perturbation parameters (scalar and tensor power spectra as well as their spectral indices) in the slow-roll approximation. We evaluate all these parameters in terms of the directional Hubble parameter during the intermediate and logamediate inflationary regimes by taking the dissipation factor as a function of the scalar field as well as a constant. In each case, we calculate the observational parameter of interest, i.e., the tensor–scalar ratio in terms of the inflaton. The graphical behavior of these parameters shows that the anisotropic model is also compatible with WMAP7 and the Planck observational data.     

Self-force on a scalar point charge in the long throat

An analytic method is presented which allows for the computation of the self-force for a static particle with a scalar charge in the region of an ultrastatic spacetime which one can call the long throat. The method is based on the approximate WKB solution of a radial mode equation for a scalar field. This field is assumed to be massless, with a coupling ξ   to the scalar curvature is satisfying the condition ξ>1/8$\xi >1/8$.