In this paper, we investigate area requirements for drawing s-t hierarchically planar graphs by straight-lines. Two drawing standards will be discussed: 1) each vertex is represented by a point and 2) grid visibifity representation (that is, a line segment is allowed to represent a vertex). For the first drawing standard, we show an exponential area lower bound needed for drawing hierarchically...

A small subset of neutrino-induced upward going muons in the SuperKamiokande detector consists of high energy muons that undergo radiative energy losses through bremsstrahlung, pair production and photo-nuclear interactions. The mean energy of the parent neutrinos of these showering upward muons is approximately 1 TeV, allowing the selection of a high energy sample of neutrinos. We present the ...

We study planar drawings of directed graphs in the L-drawing standard. We provide necessary conditions for the existence of these drawings and show that testing for the existence of a planar L-drawing is an NP-complete problem. Motivated by this result, we focus on upwardplanar L-drawings. We show that directed st-graphs admitting an upward(resp. upward-rightward-) planar L-drawing are exactly ...

One of the problems of existing irrigation networks is seepage phenomena. Seepage problem and its control in irrigation channels is one of the most important issues in the design, construction, maintenance and operation of these channels. In this study, simulated the rate of seepage and phreatic lines in the Mianab irrigation and drainage channels located in the Karun basin using mathematical t...

Atmospheric levels of methane, a potent greenhouse gas, vary greatly in the climate record and are usually thought to be due to emissions from continental wetlands. However, Tessa Hill et al. report that methane was released into the atmosphere from the oceans during the period of global warming associated with the most recent deglaciation. The results suggest that, at times, much more methane ...

In the firefighting and the graph searching problems, a contaminate spreads relatively quickly. We introduce a new model, on directed acyclic graphs, in which the contamination spreads slowly. The model was inspired by the efforts to stem the lava flow from the Eldfell volcano in ∗ Partially supported by grants from NSERC. 92 N.E. CLARKE ET AL. Iceland. The contamination starts at a source, onl...

Upper Gotvand dam is constructed on the Karun River located in the south west of Iran. In this paper, 2D and 3D models of the dam together with the foundation and abutments were constructed and several seepage analyses were carried out. Then the gypsum veins scattered throughout the foundation ground and also the seepage pattern were included in the models, hence the dissolution law of gypsum, ...

In the present study, analytical solutions are obtained for two-dimensional advection dispersion equation for conservative solute transport in a semi-infinite heterogeneous porous medium with pulse type input point source of uniform nature. The change in dispersion parameter due to heterogeneity is considered as linear multiple of spatially dependent function and seepage velocity whereas seepag...

1. House mouse Mus domesticus outbreaks in the grain-growing areas of south-eastern Australia occur irregularly and may be local or widespread, covering thousands of square kilometres. All natural and agricultural habitats are occupied when house mouse numbers are high, and the question we addressed was whether we can distinguish source and sink habitats within these agricultural landscapes so ...

The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic pet...