The purpose of this paper is to give a characterization families expander graphs via right-angled Artin groups. We prove that sequence simplicial [Formula: see text] forms family if and only certain natural mini-max invariant arising from the cup product in cohomology rings groups agrees with Cheeger constant graphs, thus allowing us characterize cohomology. This result proved more general fram...

To any prime alternating link, we associate a collection of hyperbolic right-angled ideal polyhedra by relating geometric, topological and combinatorial methods to decompose the link complement. The sum volumes these is new geometric invariant, which call volume link. We give an explicit procedure compute from diagram, prove that it lower bound for

The heat transfer performance of a solar external receiver tube with guide vanes was numerically studied under non-uniform flux conditions. Models the smooth and were built. distributions temperature, velocity, turbulence intensity, Nu predicted by these two models compared to investigate enhancement mixing effect vanes. Re α on also studied. results show that form spiraling flows, reduce maxim...

Abstract Fan systems used to transport fluids are widely and have become a major consumer of electrical energy worldwide. A significant part the available transported air in HVAC has usually been lost (in form dynamic pressure) at system outlet. It is well-known that using outlet diffusers leads this loss be reduced. In some cases, it necessary use shortened wide-angle diffusers, which higher c...

This paper describes the effects of guide vanes installed in curved conduits with main emphasis on pressure loss reduction. In parts conduits, eddy zones are created due to flow separation resulting an increased value drop. Installation can prevent creation large zones. On other hand, cross-section conduit is decreased by placing vanes, leading growth That why properties needed be selected care...

in this century due to population growth, the use of river water has become more complicated. since most rivers pass across loose and erodible areas, they always act as the most important factor of transferring eroded materials from the solid crust of the earth.  vortex basins are among the solutions known for the high-speed separation of solids from liquids (filtration). one of the problems of...

A multistage centrifugal pump is designed for pumping low-viscosity, highly volatile and flammable chemicals, including hydrocarbons, high head requirements. The five-stage consists of a double-suction impeller at the first stage followed by twin volute. impellers stages two through five are single-suction diffuser vanes return channel vanes. analytical performance calculated initially in desig...

In this article we study the right-angled Artin subgroups of a given right-angled Artin group. Starting with a graph Γ, we produce a new graph through a purely combinatorial procedure, and call it the extension graph Γ of Γ. We produce a second graph Γ k , the clique graph of Γ, by adding extra vertices for each complete subgraph of Γ. We prove that each finite induced subgraph Λ of Γ gives ris...