Small particle separation in a circulating fluidized bed riser system

Particle separation is an important area of interest in many fields, such as the coal and mineral processing industries. A circulating fluidized bed riser system has been built to investigate the separation processes. The system separated the particles into three streams which lead to the dense bin, the product bin, and the filter chamber. Promising results have been obtained which may lead to a system which is viable for commercial separation. The following categories of separation were investigated: separation based on size difference of the particles, separation based on density difference of the particles, and the practicality of separating mineral material, such as pyrite and ash, from coal. The superficial gas velocity in the riser, U 0, and the solids mass flux into the riser, G, were varied in the tests. The separation based on density difference had the most efficient results

Time-resolved gas-phase kinetic and quantum chemical studies of the reaction of silylene with oxygen

Time-resolved kinetic studies of the reaction of silylene, SiH2, generated by laser flash photolysis of phenylsilane, have been carried out to obtain rate constants for its bimolecular reaction with O-2. The reaction was studied in the gas phase over the pressure range 1-100 Torr in SF6 bath gas, at five temperatures in the range 297-600 K. The second order rate constants at 10 Torr were fitted to the Arrhenius equation: log(k/cm(3) molecule(-1) s(-1)) = (-11.08 +/- 0.04) + (1.57 +/- 0.32 kJ mol(-1))/RT ln10 The decrease in rate constant values with increasing temperature, although systematic is very small. The rate constants showed slight increases in value with pressure at each temperature, but this was scarcely beyond experimental uncertainty. From estimates of Lennard-Jones collision rates, this reaction is occurring at ca. 1 in 20 collisions, almost independent of pressure and temperature. Ab initio calculations at the G3 level backed further by multi-configurational (MC) SCF calculations, augmented by second order perturbation theory (MRMP2), support a mechanism in which the initial adduct, H2SiOO, formed in the triplet state (T), undergoes intersystem crossing to the more stable singlet state (S) prior to further low energy isomerisation processes leading, via a sequence of steps, ultimately to dissociation products of which the lowest energy pair are H2O + SiO. The decomposition of the intermediate cyclo-siladioxirane, via O-O bond fission, plays an important role in the overall process. The bottleneck for the overall process appears to be the T -> S process in H2SiOO. This process has a small spin orbit coupling matrix element, consistent with an estimate of its rate constant of 1 x 10(9) s(-1) obtained with the aid of RRKM theory. This interpretation preserves the idea that, as in its reactions in general, SiH2 initially reacts at the encounter rate with O-2. The low values for the secondary reaction barriers on the potential energy surface account for the lack of an observed pressure dependence. Some comparisons are drawn with the reactions of CH2 + O-2 and SiCl2 + O-2

Nationwide forestry applications program. Evaluation process for the ten-ecosystem study

There are no author-identified significant results in this report

A preliminary training guide for utilizing high-altitude, color-infrared photography in compiling soil maps

Instruction for acquiring and analytically processing small-scale color-infrared photography to perform a soil resources inventory over forests of the southern U.S. is provided. Planning the project; acquiring aerial photography, materials, equipment and supplemental data; and preparing the photography for analysis are discussed. The procedures for preparing ancillary and primary component overlays are discussed. The use of correlation charts and dichotomous keys for mountain landforms, water regime, and vegetation is explained

Phenological trends of vegetation in Southern England From Envisat MERIS Terrestrial Chlorophyll Index (MTCI) data

Given the close association between climate change and vegetation response there is a pressing requirement to monitor the phenology of vegetation and understand how its metrics vary over space and time. This paper explores the viability of the Envisat MTCI dataset for monitoring vegetation phenology via its estimates of chlorophyll content. The MTCI was used to construct the phenological profile of and to extract key phenological dates from mixed woodland in Southern England. Woodland phenological cycles for the time period 2003 to 2007, a period with known temperature anomalies forcing variability in the phenology of the vegetation, were derived from MERIS MTCI data. Comparisons were made with ground indicators of phenology, and furthermore, crosscomparisons with other vegetation indices, namely the NDVI and EVI derived from MODIS data were conducted. Close correspondence between MTCI and canopy phenology as indicated by ground observations was evident. Also observed was a difference between MTCI-derived phenological transition curves and key transition dates and those derived from the NDVI and EVI. Overall the research presented in this paper supports the use of the Envisat MTCI for monitoring vegetation phenology, principally due to its sensitivity to canopy chlorophyll content, a vegetation property that is a useful proxy for the canopy physical and chemical alterations associated with phenological change

Human Resource Management of US multinationals in Germany and the UK.

This research examines human resource management (HRM) in subsidiaries of US multinational firms (MNCs) operating in the UK and Germany. Together with parallel studies in Ireland and Spain it explores the potential tensions resulting from a transfer of US-type human resource (HR) policies to Europe. Whilst we expected that the liberal market British economy would not provide a major challenge for the transfer of US practices, we foresaw that the more densely institutionalized German business system would constitute a more serious barrier to transfer. This report is based on case studies of four large US MNCs. In all four firms we conducted interviews in the British and German subsidiaries, as well as the US and/or European headquarters, with HR managers, line managers and non-managerial employees. For three substantive issues – diversity management, employee participation and pay – as well as for the processual issue of ‘centralization–decentralization’ this report analyses whether the four US MNCs studied have global policies, how these are transferred to Europe and the extent to which they have to be adapted to the British and German contexts. Our findings support previous research which suggests that HR policies in US MNCs are not only relatively standardised, but also build on US domestic policies. However, the mechanisms of transfer appear to have changed. Whereas in the past, written guidelines, the transfer of home-country employees and extensive reporting seem to have been the major mechanisms employed to ensure that global policies were applied, today HR information systems, regional European headquarters and international teams of HR managers seem to play a more important role. Over the last decade, national subsidiaries in both countries have lost autonomy in HR decision-making. However, this has not been primarily in the form of recentralization towards headquarters, but rather towards the regional level and/or business unit. Turning to substantive issues, as expected, the German institutional environment represents a stronger challenge for US MNCs than the British one. Of particular importance is codetermination which affects all four firms and which in at least three of them exerts pressure on local management to adjust global polices to local conditions. However, in most cases the observed deviations were only marginal. Similarly, the German system of multi-employer bargaining does not constitute a major hurdle for US MNCs seeking to apply global practices. Although in general German host-country pressures were stronger than those in the UK, we found that UK management was able to use its role of interpreter of the local environment to force some adaptation of global policies, particularly in the substantive area of diversity management, suggesting that the extent to which local adaptation occurs is not entirely dependent on the strength of employment-relations institutions in the host country. Regarding practical implications, our research points firmly to the limits of global policies. With their knowledge of the local context subsidiary-level managers can and should have some freedom to adapt global policies to the local context. At least in Germany they have an additional role, as they have to manage a complex institutional environment. The system of collective bargaining and codetermination fosters collective HR policies that are often incompatible with the more individualistic global policies pursued by US MNCs. Nevertheless, as the case studies show, US MNCs are able to manage these institutions in such a way that the need for adaptation is minimized. This process of institutional arbitrage tends to be performed by local managers with a deep knowledge of the hostenvironment

A benchmarking study of two trauma centres highlighting limitations when standardising mortality for comorbidity

<p>Abstract</p> <p>Introduction</p> <p>A continuous process of trauma centre evaluation is essential to ensure the development and progression of trauma care at regional, national and international levels. Evaluation may be by comparison between pooled datasets or by direct benchmarking between centres. This study attempts to benchmark mortality at two trauma centres standardising this for multiple case-mix factors, which includes the prevalence of individual background pre-existing diseases within the study population.</p> <p>Methods</p> <p>Trauma patients with an Injury Severity Score (ISS) >15 admitted to the two centres in 2001 and 2002 were included in the study with the exception of those who died in the emergency department. Patient characteristics were analysed in terms of 18 case-mix factors including Glasgow Coma Scale on arrival, Injury Severity Score and the presence or absence of 9 co-morbidity types, and patient outcome was compared based on in-hospital mortality before and after standardisation.</p> <p>Results</p> <p>Crude mortality was greater at UHNS (18.2 vs 14.5%) with a non-significant odds ratio of 1.31 prior to adjusting for case-mix (P = 0.171). Adjustment for case mix using logistic regression analysis altered the odds ratio to 1.64, which was not significant (P = 0.069).</p> <p>Discussion</p> <p>This study did not demonstrate any significant difference in the outcome of patients treated at either hospital during the study period. More importantly it has raised several important methodological issues pertinent to researchers undertaking registry based benchmarking studies. Data at the two registries was collected by personnel with differing backgrounds, in formats that were not completely compatible and was collected for patients that met different admissions criteria. The inclusion of a meaningful analysis of pre-existing disease was limited by the availability of robust data and sample size. We suggest greater communication between trauma research coordinators to ensure equivalent data collection and facilitate future benchmarking studies.</p