942 resultados para HYDRAULIC REDISTRIBUTION
Hydrogeology of flooded, abandoned mine workings - an integrated hydraulic/hydrogeochemical analysis
Visual Observation of Redistribution and Dissolution of Palladium During the Suzuki–Miyaura Reaction
Resumo:
Now you see it, now you don't: A specially designed reactor that heats only a small area of Pd foil during a Suzuki-Miyaura coupling permits observation of the surface changes during the reaction. Dissolution of Pd occurs only in the heated zone, and only in the presence of aryl iodide, whereas deposition of Pd occurs preferentially on the unheated zones adjacent to the reactive zone. SEM and XPS are employed to probe the surface before and after reaction.
Resumo:
Iron and Mn redistribute in soil and saprolite during weathering. The geological weathering fronts ofcalcareous sedimentary rock were investigated by examining the bulk density, porosity, and distribution ofCa, Fe, and Mn. Core samples were taken ofsoil, saprolite, and bedrock material from both summit (HHMS-4B) and sideslope (HHMS-5A) positions on an interbedded Nolichucky shale and Maryville limestone landform in Solid Waste Storage Area 6 (SWSA-6). This is a low-level radioactive solids waste disposal site on the Dept. ofEnergy (DOE) Oak Ridge Reservation in Roane County Tennessee. This work was initiated because data about the properties of highly weathered sedimentary rock on this site were limited. The core samples were analyzed for pH, calcium carbonate equivalence (CCE), hydroxylamine-extractable (HA) Mn, and dithionite-citrate (CBD)-extractable Fe and Mn. Low pH values occurred from the soil surface down to the depth of the oxidized and leached saprolite in both cores. The CCE and HA-extractable Mn results were also influenced by the weathering that has occurred in these zones. Extractable Mn oxide was higher at a lower depth in the oxidized and leached saprolite compared with the Fe oxide, which was higher in the overlying soil solum. Amounts of Mn oxides were higher in the sideslope core (HHMS-5A) than in the summit core (HHMS-4B). Iron was more abundant in the deeper weathered summit core, but the highest value, 39.4 g kg-1, was found at 1.8 to 2.4 m in the sideslope core. The zone encompassing the oxidized and partially leached saprolite down to the unoxidized and unleached bedrock had higher densities and larger quantities of CaCO3 than the soil solum and oxidized and leached saprolite. The overlying soil and oxidized and leached saprolite had lower pH and CCE values and were higher in Fe and Mn oxides than the oxidized and unleached saprolite. The distribution of Fe and Mn is important when evaluating soil and saprolite for hazardous waste disposal site assessment.
Resumo:
This paper investigates the problem of seepage under the floor of hydraulic structures considering the compartment of flow that seeps through the surrounding banks of the canal. A computer program, utilizing a finite-element method and capable of handling three-dimensional (3D) saturated–unsaturated flow problems, was used. Different ratios of canal width/differential head applied on the structure were studied. The results produced from the two-dimensional (2D) analysis were observed to deviate largely from that obtained from 3D analysis of the same problem, despite the fact that the porous medium was isotropic and homogeneous. For example, the exit gradient obtained from 3D analysis was as high as 2.5 times its value obtained from 2D analysis. Uplift force acting upwards on the structure has also increased by about 46% compared with its value obtained from the 2D solution. When the canal width/ differential head ratio was 10 or higher, the 3D results were comparable to the 2D results. It is recommended to construct a core of low permeability soil in the banks of canal to reduce the seepage losses, uplift force, and exit gradient.
Resumo:
We consider here how cultural and socioeconomic dimensions of justice beyond the state are related. First we examine cosmopolitan theories that have drawn on John Rawls's egalitarian liberal framework to argue that a just global order requires substantive, transnational redistribution of material resources. We then assess the view, ironically put forward by Rawls himself, that this perspective is ethnocentric and insufficiently tolerant of non-liberal cultures. We argue that Rawls is right to be concerned about the danger of ethnocentrism, but wrong to assume that this requires us to reject the case for substantive redistribution across state boundaries. A more compelling account of justice beyond the state will integrate effectively socioeconomic and cultural aspects of justice. We suggest that this approach is best grounded in a critical theory of recognition that responds to the damage caused to human relations by legacies of historical injustice.
Resumo:
This paper presents findings of research into the role of church nominees on school governing bodies. The data is drawn mainly from a wider study of school ethos and school governance undertaken in Northern Ireland in the period 1994 to 1997. The paper raises the question of the future roles and responsibilities of church nominees after legislative changes to the composition and responsibilities of school governing bodies. It also considers recent social and attitudinal change and explains how the combination of these factors have created a situation whereby the power of the churches in the individual school governing body is no longer guaranteed