Suppose that under the action of gravity, liquid drains through the unit d-cube via a minimal-length network of channels constrained to pass through random sites and to flow with nonnegative component in one of the canonical orthogonal basis directions of Rd, d ≥ 2. The resulting network is a version of the so-called minimal directed spanning tree. We give laws of large numbers and convergence ...

Introduction: Valley network systems on Mars remain the most unequivocal evidence that water carved the surface of the planet in the distant past and the climate was different than today. Most of these systems date from the Noachian [1], the p eriod of heavy bombardment which is >3.7 Ga [2], although local or regional formation seems to have continued to more recent times [3]. The discovery of ...

In order to study the gas migration in gas-bearing coal, and reasonably arrange drainage boreholes improve efficiency of drainage, a gas-solid coupling model is established based on pore-fracture dual medium porous model. The solid deformation coal body, seepage diffusion, adsorption desorption are considered this COMSOL software used simulate change matrix fracture under single borehole extrac...

The drainage networks of catchment areas burned by wildfire were analysed at several scales. The smallest scale (1–1000 m) representative of hillslopes, and the small scale (1000 m to 1 km), representative of small catchments, were characterized by the analysis of field measurements. The large scale (1–1000 km), representative of perennial stream networks, was derived from a 30-m digital elevat...

Sand coverings account for a large part of the cost of a project. The purpose of this study is to evaluate the performance of different coatings for filtration of underground drains and reduce the cost of cornfield farms. The experiments were carried out in farm in Salman Farsi. The subsoil drainage was fitted to each test piece with a length of 120 meters, a diameter of 100 mm, and a distance ...

O'Neil designed a set of suction cups which, because of more efficient lateral pull and greater maneuverability, were claimed to be more efficient and perinatally safer than the Malmström model. These claims were checked by comparing the two instruments in a randomized controlled trial comprising 410 attempted elective extractions. The two instrument groups were comparable at entry and the oper...