نتایج جستجو برای: sandstone
تعداد نتایج: 4843 فیلتر نتایج به سال:
Numerical micropermeametry is performed on three-dimensional porous samples having a linear size of approximately 3 mm and a resolution of 7.5 microm. One of the samples is a microtomographic image of Fontainebleau sandstone. Two of the samples are stochastic reconstructions with the same porosity, specific surface area, and two-point correlation function as the Fontainebleau sample. The fourth...
The main purpose of this study was to examine the effect of chalk on the friction coefficient between climber's fingers and two different rock types (sandstone and limestone). The secondary purpose was to investigate the effects of humidity and temperature on the friction coefficient and on the influence of chalk. Eleven experienced climbers took part in this study and 42 test sessions were per...
A closed-form description is proposed to explain nonlinear and slow dynamics effects exhibited by sandstone bars in longitudinal resonance experiments. Along with the fast subsystem of longitudinal nonlinear displacements we examine the strain-dependent slow subsystem of broken intergrain and interlamina cohesive bonds. We show that even the simplest but phenomenologically correct modeling of t...
The present work investigates whether dielectric spectroscopy can be used to detect contamination, which may leach in a natural porous material, due to the spreading of contaminants. For this purpose, dielectric and conductivity measurements, in the frequency range from 10 mHz to 1 MHz, were carried out in sandstone samples, partially filled or saturated with solutions of leachates, at differen...
Abstract The effects of changes in climate on aquifer storage and groundwater flow to rivers have been investigated using an idealized representation of the aquifer/river system. The generalized aquifer/river model can incorporate spatial variability in aquifer transmissivity and is applied with parameters characteristic of Chalk and Triassic sandstone aquifers in the United Kingdom, and is als...
A GPR survey was carried out in advance of archaeological excavations at Madjedbebe (formerly known as Malakunanja II), a sandstone rock shelter in western Arnhem Land (Australia) containing numerous Aboriginal burials. GPR revealed subsurface patterning of rocks in the shelter deposits and archaeological excavation demonstrated that these were related to burials. Post-excavation, GIS and stati...
We consider a family of statistical measures based on the Euler-Poincaré characteristic of n-dimensional space that are sensitive to the morphology of disordered structures. These measures embody information from every order of the correlation function but can be calculated simply by summing over local contributions. We compute the evolution of the measures with density for a range of disordere...
Although shale gas plays have been in the spotlight recently, natural gas in tight sandstones is actually also an important hydrocarbon resource. In many cases, tight gas sandstone resources can be developed more easily than shale gas reservoirs as the rocks generally have higher quartz content, and are more brittle and easier to complete for production. This chapter first gives an overview of ...
Patterns of plant distribution by palaeoenvironment were examined across the Pennsylvanian-Permian transition in North-Central Texas. Stratigraphically recurrent packages of distinct lithofacies, representing different habitats, contain qualitatively and quantitatively different macrofloras and microfloras. The species pools demonstrate niche conservatism, remaining closely tied to specific hab...
—The study objective was to investigate the response of salmonid populations to disturbance in Oregon Coast Range streams in two rock types, basalt and sandstone. Salmonid abundance was estimated in a total of 30 km of channel in 10 Oregon Coast Range streams with similar basin areas (14–20 km2). These basins had a range of disturbance caused by timber harvest, fire, and salvage logging. Mean c...
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