20 resultados para Ore-dressing.

em CentAUR: Central Archive University of Reading - UK


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Local Agenda 21 seeks the meaningful involvement of a wide range of local groups and stakeholders in the formulation and implementation of public policy and a free flow of communication and discussion between them and their respective local authorities (and other areas and levels of decision-making). This paper explores the reality of this process using case study evidence from local planning practice in Liverpool (in the north of England) and Reading (in the south of the country). It concentrates on the interaction between LA21 groups and local planning authorities around the preparation of local land use plans and other policy initiatives and the day-to-day regulation of development permits. The paper builds on ‘New Institutionalist’ theory to explore the constraints and opportunities for significant transformations in social, political and economic ‘structures’ or ‘ways of doing things’ through the LA21 process. It concludes that the two cases provide evidence of mixed success in achieving such changes in established planning practices.

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The 2014 Graham proposals aimed at reducing recidivism are unlikely to achieve the desired goals. It is argued that due consideration must be had for the future of the rescued entity. Further, both the viability review and the proposed capital structure of the rescued entity must be carefully assessed.

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In recent years there has been an increasing awareness of the radiological impact of non-nuclear industries that extract and/or process ores and minerals containing naturally occurring radioactive material (NORM). These industrial activities may result in significant radioactive contamination of (by-) products, wastes and plant installations. In this study, scale samples were collected from a decommissioned phosphoric acid processing plant. To determine the nature and concentration of NORM retained in pipe-work and associated process plant, four main areas of the site were investigated: (1) the 'Green Acid Plant', where crude acid was concentrated; (2) the green acid storage tanks; (3) the Purified White Acid (PWA) plant, where inorganic impurities were removed; and (4) the solid waste, disposed of on-site as landfill. The scale samples predominantly comprise the following: fluorides (e.g. ralstonite); calcium sulphate (e.g. gypsum); and an assemblage of mixed fluorides and phosphates (e.g. iron fluoride hydrate, calcium phosphate), respectively. The radioactive inventory is dominated by U-238 and its decay chain products, and significant fractionation along the series occurs. Compared to the feedstock ore, elevated concentrations (<= 8.8 Bq/g) of U-238 Were found to be retained in installations where the process stream was rich in fluorides and phosphates. In addition, enriched levels (<= 11 Bq/g) of Ra-226 were found in association with precipitates of calcium sulphate. Water extraction tests indicate that many of the scales and waste contain significantly soluble materials and readily release radioactivity into solution. (c) 2005 Elsevier Ltd. All rights reserved.

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Trace elements may present an environmental hazard in the vicinity of mining and smelting activities. However, the factors controlling trace element distribution in soils around ancient and modem mining and smelting areas are not always clear. Tharsis, Riotinto and Huelva are located in the Iberian Pyrite Belt in SW Spain. Tharsis and Riotinto mines have been exploited since 2500 B.C., with intensive smelting taking place. Huelva, established in 1970 and using the Flash Furnace Outokumpu process, is currently one of the largest smelter in the world. Pyrite and chalcopyrite ore have been intensively smelted for Cu. However, unusually for smelters and mines of a similar size, the elevated trace element concentrations in soils were found to be restricted to the immediate vicinity of the mines and smelters, being found up to a maximum of 2 kin from the mines and smelters at Tharsis, Riotinto and Huelva. Trace element partitioning (over 2/3 of trace elements found in the residual immobile fraction of soils at Tharsis) and soil particles examination by SEM-EDX showed that trace elements were not adsorbed onto soil particles, but were included within the matrix of large trace element-rich Fe silicate slag particles (i.e. 1 min circle divide at least 1 wt.% As, Cu and Zn, and 2 wt.% Pb). Slag particle large size (I mm 0) was found to control the geographically restricted trace element distribution in soils at Tharsis, Riotinto and Huelva, since large heavy particles could not have been transported long distances. Distribution and partitioning indicated that impacts to the environment as a result of mining and smelting should remain minimal in the region. (c) 2006 Elsevier B.V. All rights reserved.

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In January 1992, there was a major pollutant event for the River Canon and downstream with its confluence to the River Fal and the Fal estuary in the west Cornwall. This incident was associated with the discharge of several million gallons of highly polluted water from the abandoned Wheal Jane tin mine that also extracted Ag, Cu and Zn ore. Later that year, the Centre for Ecology and Hydrology (CBH; then Institute of Hydrology) Wallingford undertook daily monitoring of the River Canon for a range of major, minor and trace elements to assess the nature and the dynamics of the pollutant discharges. These data cover an 18-month period when there remained major water-quality problems after the initial phase of surface water contamination. Here, a summary is provided of the water quality found, as a backdrop to set against subsequent remediation. Two types of water-quality determinant grouping were observed. The first type comprises the determinants B, Cs, Ca, Li, K, Na, SO4, Rb and Sr, and their concentrations are positively correlated with each other but inversely correlated with flow. This type of water-quality determinant shows variations in concentration that broadly link to the normal hydrogeochemical processes within the catchment, with limited confounding issues associated with mine drainage. The second type of water-quality determinant comprises Al, Be, Cd, Ce, Co, Cu, Fe, La, Pb, Pr, Nd, Ni, Si, Sb, U, Y and Zn, and concentrations for all this group are positively correlated. The determinants in this second group all have concentrations that are negatively correlated with pH. This group links primarily to pollutant mine discharge. The water-quality variations in the River Camon are described in relation to these two distinct hydrogeochemical groupings. (C) 2004 Elsevier B.V All rights reserved.

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Intensification of crop production in the mid-hills of Nepal has led to concerns that nitrogen loss by leaching may increase. This study estimated the amount of N leached during two years from rainfed terraces (bari-land) at three locations in Nepal. Maize or upland rice grown in the monsoon season was given either no nutrient inputs or inputs via either nitrogen fertilizer or farmyard manure. Nitrate concentration in soil solution was measured regularly with porous ceramic cup samplers and drainage estimated from a simple soil water balance. Estimated losses of nitrogen by leaching ranged from 0 to 63.5 kg N ha(-1) depending on location and the form of nitrogen applied. Losses from plots receiving no nutrient inputs were generally small (range: 0-35 kg N ha(-1)) and losses from plots where nitrogen was applied as manure (range: 2-41 kg N ha(-1)) were typically half those from plots with nitrogen applied as fertilizer. Losses during the post-monsoon crops of finger millet were small (typically <5% of total loss) although losses from the one site with blackgram were larger (about 13%). The highest concentrations of nitrate in solution were measured early in the season as the monsoon rains began and immediately following fertilizer applications. Leaching losses are likely to be minimised if manure is applied as a basal nutrient dressing followed by fertilizer nitrogen later in the season.

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This study compared the effect of supplementing maize stover (MS) with cowpea (Vigna unguiculata) haulms or commercial concentrate (CC) on feed intake, nutrient digestibility, live weight gain and carcass yield of male Ethiopian Highland sheep. Two cowpea genotypes, 12688 (forage) and IT96D-774 (dual-purpose), were used. A randomised block design was applied with groups of eight sheep, blocked by weight, allocated to one of six treatments; MS ad libitum either unsupplemented or supplemented daily with 150 or 300g dry matter (DM) of either cowpea or CC. MS contained more neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin than either cowpeas or CC Crude protein (CP) content of the forage-type cowpeas was higher than either dual-purpose or CC, while MS had the lowest CP content Relative to the negative control group, cowpea at either level significantly (P < 0.01) increased both MS intake and total NDF and lignin. Supplementation significantly (P < 0.01) increased nitrogen (N) intakes relative to the negative control, with N intake for CC and dual-purpose cowpea (high level) being similar to the intakes for cowpeas at 150g. N intake with the forage-type cowpea offered at higher levels was significantly (P < 0.01) greater than the other groups. No significant differences (P > 0.01) in MS intake were identified between cowpeas at either level or CC and, although intake level of CC increased, it did not differ significantly from the negative control group. Supplementation significantly (P < 0.01) improved average daily gain, with the negative control group losing weight over the experimental period, and increased final live weight, carcass cold weight and dressing percentage. Supplementation significantly improved the apparent digestibility of DM, organic matter and NDF, with no significant difference found between cowpeas at either level. N retention was negative for sheep offered only MS, but positive with all supplements, with cowpeas improving N retention to a greater extent than CC. Interestingly, N retention/N intake was higher with cowpeas offered at the lower level suggesting an improvement in utilisation efficiency. The results indicate that the supplementation of MS with cowpea enhanced ruminant production through improvements in digestibility and intake. Further, as production improvements associated with the two levels of supplementation did not differ significantly, it is suggested that where limited quantities of cowpea are available, it may be of greater nutritional benefit to offer smaller quantities over an increased number of animal days.

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Multiple regression analysis is a statistical technique which allows to predict a dependent variable from m ore than one independent variable and also to determine influential independent variables. Using experimental data, in this study the multiple regression analysis is applied to predict the room mean velocity and determine the most influencing parameters on the velocity. More than 120 experiments for four different heat source locations were carried out in a test chamber with a high level wall mounted air supply terminal at air change rates 3-6 ach. The influence of the environmental parameters such as supply air momentum, room heat load, Archimedes number and local temperature ratio, were examined by two methods: a simple regression analysis incorporated into scatter matrix plots and multiple stepwise regression analysis. It is concluded that, when a heat source is located along the jet centre line, the supply momentum mainly influences the room mean velocity regardless of the plume strength. However, when the heat source is located outside the jet region, the local temperature ratio (the inverse of the local heat removal effectiveness) is a major influencing parameter.

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The effects of milk protein fortification on the texture and microstructure of cottage cheese curd were evaluated. Protein powder (92.6% protein) was added to the skim milk at a level of 0.4% (w/w) to produce curds. Control curds with no protein powder addition were also produced. These curds were analysed for differences in yield, total solids, curd size, texture and structure. It was found that the addition of protein powder contributed to a significant yield increase, which can be attributed to increased water retention, with better curd size distribution. Control curds were firmer than the fortified curds and the structure showed less open-pore structure as revealed by electron microscopy. However, the addition of dressing masked the textural differences, and a sensory panel was unable to distinguish between cheeses produced from fortified milk and controls.

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Background Little is known about the relative effects of exposure to postnatal depression and parental conflict on the social functioning of school-aged children. This is, in part, because of a lack of specificity in the measurement of child and parental behaviour and a reliance on children's reports of their hypothetical responses to conflict in play. Methods In the course of a prospective longitudinal study of children of postnatally depressed and well women, 5-year-old children were videotaped at home with a friend in a naturalistic dressing-up play setting. As well as examining possible associations between the occurrence of postnatal depression and the quality of the children's interactions, we investigated the influence of parental conflict and co-operation, and the continuity of maternal depression. The quality of the current mother-child relationship was considered as a possible mediating factor. Results Exposure to postnatal depression was associated with increased likelihood, among boys, of displaying physical aggression in play with their friend. However, parental conflict mediated the effects of postnatal depression on active aggression during play, and was also associated with displays of autonomy and intense conflict. While there were no gender effects in terms of the degree or intensity of aggressive behaviours, girls were more likely to express aggression verbally using denigration and gloating whereas boys were more likely to display physical aggression via interpersonal and object struggles. Conclusions The study provided evidence for the specificity of effects, with strong links between parental and child peer conflict. These effects appear to arise from direct exposure to parental conflict, rather than indirectly, through mother-child interactions.

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The continuous ranked probability score (CRPS) is a frequently used scoring rule. In contrast with many other scoring rules, the CRPS evaluates cumulative distribution functions. An ensemble of forecasts can easily be converted into a piecewise constant cumulative distribution function with steps at the ensemble members. This renders the CRPS a convenient scoring rule for the evaluation of ‘raw’ ensembles, obviating the need for sophisticated ensemble model output statistics or dressing methods prior to evaluation. In this article, a relation between the CRPS score and the quantile score is established. The evaluation of ‘raw’ ensembles using the CRPS is discussed in this light. It is shown that latent in this evaluation is an interpretation of the ensemble as quantiles but with non-uniform levels. This needs to be taken into account if the ensemble is evaluated further, for example with rank histograms.

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The waste materials generated in the nuclear fuel cycle are very varied,ranging from the tailings arising from mining and processing uranium ore, depleted uranium in a range of chemical forms, to a range of process wastes of differing activities and properties. Indeed, the wastes generated are intimately linked to the options selected in operating the nuclear fuel cycle, most obviously to the management of spent fuel. An open fuel cycle implies the disposal of highly radioactive spent fuel, whereas a closed fuel cycle generates a complex array of waste streams. On the other hand, a closed fuel cycle offers options for waste management, for example reduction in highly active waste volume, decreased radiotoxicity, and removal of fissile material. Many technological options have been proposed or explored, and each brings its own particular mix of wastes and environmental challenges.

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The translation of an ensemble of model runs into a probability distribution is a common task in model-based prediction. Common methods for such ensemble interpretations proceed as if verification and ensemble were draws from the same underlying distribution, an assumption not viable for most, if any, real world ensembles. An alternative is to consider an ensemble as merely a source of information rather than the possible scenarios of reality. This approach, which looks for maps between ensembles and probabilistic distributions, is investigated and extended. Common methods are revisited, and an improvement to standard kernel dressing, called ‘affine kernel dressing’ (AKD), is introduced. AKD assumes an affine mapping between ensemble and verification, typically not acting on individual ensemble members but on the entire ensemble as a whole, the parameters of this mapping are determined in parallel with the other dressing parameters, including a weight assigned to the unconditioned (climatological) distribution. These amendments to standard kernel dressing, albeit simple, can improve performance significantly and are shown to be appropriate for both overdispersive and underdispersive ensembles, unlike standard kernel dressing which exacerbates over dispersion. Studies are presented using operational numerical weather predictions for two locations and data from the Lorenz63 system, demonstrating both effectiveness given operational constraints and statistical significance given a large sample.