Orderings of filters in terms of reloids ∗ Extensions of
Orderings of filters which extend Rudin-Keisler preorder of ultrafilters are described in terms of reloids that (roughly speaking) is filters on sets of binary relations between some sets. Also it is defined isomorphism of filters which extends Rudin-Keisler equivalence of ultrafilters.
On the Rudin-Keisler order on ultrafilters
Abstract We prove a theorem, which enables to construct some pairwise incomparable ultrafilters under Rudin-Keisler order.
The Study of Relationship between Berm Width and Debris Flow at the Slope
The purpose of this study is to estimate the behavior and the mechanism of debris flow at the end of mountain side when a berm was set on the inclined plane. The numerical model was performed by using the Finite Difference Method(FDM) based on the equation for the mass conservation and momentum conservation. In order to measure the behavior of the debris flow, the debris flow of a straight channel slope and the debris flow of channel slope with 3 types of berms were compared. First, the flow discharge and the sediment volume concentration at the downstream of the channel slope, depending on the various berm width and the different inflow discharges at the upstream of the channel were analyzed. The longer the berm width, the flow discharge at the downstream of the channel was decreased and the high flow fluctuation was reduced by a berm. And it means that a berm can effect for the delay of the debris flow. Through Root Mean Square ratio(RMS) comparison, the flow discharge of the channel slope with a berm was lower than that of a straight channel slope. The longer the berm width, for the sediment volume concentration, an inflection point did not show but mild curve. Because the low sediment concentration with water mixture by a berm continuously flow at the downstream end, it will be effect for reducing the disaster caused by debris flow. The results of this study will provide useful information in predicting and preventing disaster caused by the debris flow.