Downstream scour of combined flow over weirs and below gates

River morphodynamics and sediment transportSediment-structure interactio

Topological Black Holes of (n+1)-dimensional Einstein-Yang-Mills Gravity

We present the topological solutions of Einstein gravity in the presence of a non-Abelian Yang-Mills field. In ($n+1$) dimensions, we consider the $So(n(n-1)/2-1,1)$ semisimple group as the Yang-Mills gauge group, and introduce the black hole solutions with hyperbolic horizon. We argue that the 4-dimensional solution is exactly the same as the 4-dimensional solution of Einstein-Maxwell gravity, while the higher-dimensional solutions are new. We investigate the properties of the higher-dimensional solutions and find that these solutions in 5 dimensions have the same properties as the topological 5-dimensional solution of Einstein-Maxwell (EM) theory although the metric function in 5 dimensions is different. But in 6 and higher dimensions, the topological solutions of EYM and EM gravities with non-negative mass have different properties. First, the singularity of EYM solution does not present a naked singularity and is spacelike, while the singularity of topological Reissner-Nordstrom solution is timelike. Second, there are no extreme 6 or higher-dimensional black holes in EYM gravity with non-negative mass, while these kinds of solutions exist in EM gravity. Furthermore, EYM theory has no static asymptotically de Sitter solution with non-negative mass, while EM gravity has.Comment: 14 pages, 2 figures, accepted by Mod. Phys. Lett.

Improving employees' performance through internal marketing and organizational learning: mediating role of organizational innovation in an emerging market

This study identifies a specific relationship between internal marketing and organizational learning as the key drivers of organizational innovation, which build employees performance in the context of the petroleum industry. A model of the antecedents of organizational innovation was examined in a survey conducted among managers and employed specialists working in the oil industry in Iran. Structural equation modelling via Smart PLS was employed to gain insight into the various influences and relationships. We empirically scrutinized relationships between these constructs by validating a conceptual model employing SEM. The results indicate that internal marketing and organizational learning are key drivers of organizational innovation, which they are build employees performance. As well as, the results clarify that it is possible to improve the level of employee performance even through the complementary partial mediating role of organizational innovation. Additionally, this study makes a managerial contribution to the understanding of internal marketing, organizational learning and innovation on employee performance

Spacetimes with Longitudinal and Angular Magnetic Fields in Third Order Lovelock Gravity

We obtain two new classes of magnetic brane solutions in third order Lovelock gravity. The first class of solutions yields an $(n+1)$-dimensional spacetime with a longitudinal magnetic field generated by a static source. We generalize this class of solutions to the case of spinning magnetic branes with one or more rotation parameters. These solutions have no curvature singularity and no horizons, but have a conic geometry. For the spinning brane, when one or more rotation parameters are nonzero, the brane has a net electric charge which is proportional to the magnitude of the rotation parameters, while the static brane has no net electric charge. The second class of solutions yields a pacetime with an angular magnetic field. These solutions have no curvature singularity, no horizon, and no conical singularity. Although the second class of solutions may be made electrically charged by a boost transformation, the transformed solutions do not present new spacetimes. Finally, we use the counterterm method in third order Lovelock gravity and compute the conserved quantities of these spacetimes.Comment: 15 pages, no figur

Topological Black Holes in Lovelock-Born-Infeld Gravity

In this paper, we present topological black holes of third order Lovelock gravity in the presence of cosmological constant and nonlinear electromagnetic Born-Infeld field. Depending on the metric parameters, these solutions may be interpreted as black hole solutions with inner and outer event horizons, an extreme black hole or naked singularity. We investigate the thermodynamics of asymptotically flat solutions and show that the thermodynamic and conserved quantities of these black holes satisfy the first law of thermodynamic. We also endow the Ricci flat solutions with a global rotation and calculate the finite action and conserved quantities of these class of solutions by using the counterterm method. We compute the entropy through the use of the Gibbs-Duhem relation and find that the entropy obeys the area law. We obtain a Smarr-type formula for the mass as a function of the entropy, the angular momenta, and the charge, and compute temperature, angular velocities, and electric potential and show that these thermodynamic quantities coincide with their values which are computed through the use of geometry. Finally, we perform a stability analysis for this class of solutions in both the canonical and the grand-canonical ensemble and show that the presence of a nonlinear electromagnetic field and higher curvature terms has no effect on the stability of the black branes, and they are stable in the whole phase space.Comment: 14 page