Lightlike hypersurfaces of an indefinite Kaehler manifold of a quasi-constant curvature

We study lightlike hypersurfaces M of an indefinite Kaehler manifold M̅ of quasi-constant curvature subject to the condition that the characteristic vector field ζ of M̅ is tangent to M. First, we provide a new result for such a lightlike hypersurface. Next, we investigate such a lightlike hypersurface M of M̅ such that(1) the screen distribution S(TM) is totally umbilical or(2) M is screen conformal.

A characterization of minimal ascreen null hypersurfaces of $(LCS)$-space forms

In the present paper, we study nontotally geodesic minimal ascreen null hypersurface, $M$, of a Lorentzian concircular structure $(LCS)$-space form of constant curvature $0$ or $1$. We prove that; if the Ricci tensor of $M$ is parallel with respect to any leaf of its screen distribution, then $M$ is isometric to a product of a null curve and spheres.

Radical screen transversal lightlike submanifolds of indefinite Kaehler manifolds admitting a quarter-symmetric non-metric connection

We study radical screen transversal ([Formula: see text])-lightlike submanifolds of an indefinite Kaehler manifold admitting a quarter-symmetric non-metric connection and obtain a necessary and sufficient condition for the screen distribution of a radical [Formula: see text]-lightlike submanifold to be integrable. We also study totally umbilical radical [Formula: see text]-lightlike submanifolds and obtain some characterization theorems for a radical [Formula: see text]-lightlike submanifold to be a lightlike product manifold. Finally, we establish some results regarding the vanishes of null sectional curvature.

Half lightlike submanifolds of a semi-Riemannian manifold of quasi-constant curvature

We study the geometry of half lightlike submanifolds (M,g,S(TM), S(TM?)) of a semi-Riemannian manifold (M~,g~) of quasi-constant curvature subject to the following conditions; (1) the curvature vector field ? of M~ is tangent to M, (2) the screen distribution S(TM) of M is either totally geodesic or totally umbilical in M, and (3) the co-screen distribution S(TM?) of M is a conformal Killing distribution.

On Co-screen Conformality of 1-lightlike Submanifolds in a Lorentzian Manifold

In this paper, the co-screen conformal 1-lightlike submanifolds of a Lorentzian manifoldare introduced as a generalization of co-screen locally half-lightlike submanifolds in(Wang, Wang {\&} Liu, 2013; Wang {\&} Liu, 2013) and two examples are given whichone is co-screen locally conformal andthe other is not. Some results are obtained on these submanifolds whichthe co-screen distribution is conformal Killing on the ambient manifold.The induced Ricci tensor of co-screen conformal 1-lightlike submanifolds isinvestigated.

Az online világ új hatalmasai

Stuart Cunningham – Jon Silver: Screen Distribution and the New King Kongs of the Online World (Palgrave Macmillan, 2013) című könyvéről

Research on Performance of Foundry Sand under the Effect of Chemical Binder

This paper makes an experiental research on the performance of foundry sand under the effect of chemical binder. It discoveries the raw sand with different origin will have different properties even though they have the same particle size. The properties of their molding sand are also obviously different. For the raw sand that in the same particle size with similar acid demand value and four-screen distribution, the better grain shape will earn them a higher molding sand strength even though they have higher clay content. Under the effect of liquid binder, compared to the molding sand mixed from the sand of three-screen distribution, the molding sand mixed from those of four-screen distribution sand with other properties similar will have a higher tensile strength While under the effect of solid phenolic resin adhesive, the three-screen sand with good grain shape will have a high sand strength.