In the present study, flow over flat and pooled stepped spillways was simulated three dimensionally. The VOF method and k- ε (RNG) turbulent model was used to simulate the flow over the stepped spillway. The results indicated that the numerical model was acceptably capable of simulating the flow over the pooled and flat stepped spillways for different discharges. Following that, the effect of d...

We demonstrate an infinite family of pseudoline arrangements, in which an arrangement of n pseudolines has no member incident to more than 4n/9 points of intersection. (This shows the “Strong Dirac” conjecture to be false for pseudolines.) We also prove non-trivial lower bounds on the maximum number of intersection points on any curve in an arrangement of curves in the plane, for various classe...

Among the many ways to view oriented matroids as geometrical objects, we consider two that have special properties: • Bland’s analysis of complementary subspaces in IRn [2] has the special feature that it simultaneously and symmetrically represents a realizable oriented matroid and its dual; • Lawrence’s topological representation of oriented matroids by arrangements of pseudospheres [4] has th...

We study two kinds of segment orders, using definitions first proposed by Farhad Shahrokhi. Although the two kinds of segment orders appear to be quite different, we prove several results suggesting that the are very much the same. For example, we show that the following classes belong to both kinds of segment orders: (1) all posets having dimension at most 3; (2) interval orders; and for n ≥ 3...

We describe an incremental algorithm to enumerate the isomorphism classes of double pseudoline arrangements. The correction of our algorithm is based on the connectedness under mutations of the spaces of one-extensions of double pseudoline arrangements, proved in this paper. Counting results derived from an implementation of our algorithm are also reported.

Although field observations of sudden spillway releases highlighted strong aeration of dam break wave flows, no study investigated these two-phase flow characteristics. New original experiments were conducted down a 24 m long stepped waterways. Dam break wave propagation showed an equivalent flow resistance similar to steady flow conditions (f ~ 0.05). Detailed unsteady air-water flow measureme...

This study presents a novel approach for realizing miniaturized multi layer folded tri band micro-strip band pass filter for Wireless Local Area Network (WLAN) and Worldwide interoperatability for Microwave Access (WiMAX) applications. The proposed filter consists of a pair of folded hairpin stepped impedance resonators and pair of open loop resonators to achieve tri-band performance. The size ...

Let GH(S; H) be the bipartite graph with partition sets S and H , the set of simplices and hyperplanes of H, where simplex s∈ S is adjacent to hyperplane h∈H if one facet of s lies on h. In this paper, we give a complete characterization of GH(S; H) when H is a -arrangement. We also study GH(S; H) when H is a pseudoline arrangement. c © 2001 Elsevier Science B.V. All rights reserved.