Effects of slurry rheology on industrial grinding performance

To determine the effect of slurry rheology on industrial grinding performance, 45 surveys were conducted on 16 full-scale grinding mills in five sites. Four operating variables - mill throughput, slurry density, slurry viscosity and feed fines content-were investigated. The rheology of the mill discharge slurries was measured either on-line or off-line, and the data were processed using a standard procedure to obtain a full range of flow curves. Multi-linear regression was employed as a statistical analysis tool to determine whether or not rheological effects exert an influence on industrial grinding, and to assess the influence of the four mill operating conditions on mill performance in terms of the Grinding Index, a criterion describing the overall breakage of particles across the mill. The results show that slurry rheology does influence industrial grinding. The trends of these effects on Grinding Index depend upon the rheological nature of the slurry-whether the slurries are dilatant or pseudoplastic, and whether they exhibit a high or low yield stress. The interpretation of the regression results is discussed, the observed effects are summarised, and the potential for incorporating rheological principles into process control is considered, Guidelines are established to improve industrial grinding operations based on knowledge of the rheological effects. This study confirms some trends in the effect of slurry rheology on grinding reported in the literature, and extends these to a broader understanding of the relationship between slurry properties and rheology, and their effects on industrial milling performance. (C) 2002 Elsevier Science B.V. All rights reserved.

Investigation of the effects of chrome ball charge on slurry rheology and milling performance

Ten surveys of the ball milling circuit at the Mt Isa Mines (MIM) Copper Concentrator were conducted aiming to identify any changes in slurry theology caused by the use of chrome balls charge, and the associated effect on grinding performance. Slurry theology was measured using an on-line viscometer. The data were mass balanced and analysed with statistical tools. Comparison of the rheogram demonstrated that slurry density and fines content affected slurry rheology significantly, while the effect of the chrome ball charge being negligible. Statistical analysis showed the effects of mill throughput and cyclone efficiency on the Grinding Index (a term describing the overall breakage). There was no difference in the Grinding Index between using the chrome ball charge and the ordinary steel ball charge. (C) 2002 Elsevier Science Ltd. All rights reserved.

Relationships between nutrition screening checklists and the health and well-being of older Australian women

Objectives: To examine associations between nutrition screening checklists and the health of older women. Design: Cross-sectional postal survey including measures of health and health service utilisation, as well as the Australian Nutrition Screening Initiative (ANSI), adapted from the Nutrition Screening Initiative (NSI). Setting: Australia, 1996. Subjects: In total, 12 939 women aged 70-75 years randomly selected as part of the Australian Longitudinal Study on Women's Health. Results: Responses to individual items in the ANSI checklist, and ANSI and NSI scores, were associated with measures of health and health service utilisation. Women with high ANSI and NSI scores had poorer physical and mental health, higher health care utilisation and were less likely to be in the acceptable weight range. The performance of an unweighted score (TSI) was also examined and showed similar results. Whereas ANSI classified 30% of the women as 'high-risk', only 13% and 12% were classified as 'high-risk' by the NSI and TSI, respectively. However, for identifying women with body mass index outside the acceptable range, sensitivity, specificity and positive predictive values for all of these checklists were less than 60%. Conclusions: Higher scores on both the ANSI and NSI are associated with poorer health. The simpler unweighted method of scoring the ANSI (TSI) showed better discrimination for the identification of 'at risk' women than the weighted ANSI method. The predictive value of individual items and the checklist scores need to be examined longitudinally.

Linguistic evaluation method for the environmental assessment of infrastructure projects

A soft linguistic evaluation method is proposed for the environmental assessment of physical infrastructure projects based on fuzzy relations. Infrastructure projects are characterized in terms of linguistic expressions of 'performance' with respect to factors or impacts and the 'importance' of those factors/impacts. A simple example is developed to illustrate the method in the context of three road infrastructure projects assessed against five factors/impacts. In addition, a means to include hard or crisp factors is presented and illustrated with respect to a sixth factor.

Seasonal changes in the diving performance of the bimodally respiring freshwater turtle Rheodytes leukops in a natural setting

The objective of this study was to investigate how seasonally fluctuating environmental conditions influence the diving performance of the highly aquatic, bimodally respiring turtle Rheodytes leukops in a natural setting. Over four consecutive seasons (Austral autumn 2000 to summer 2001), the diving behaviour of adult turtles was recorded via pressure-sensitive time-depth recorders within Marlborough Creek, central Queensland, Australia. Short surfacing intervals recorded for R. leukops in winter suggest that the species utilizes aquatic respiration as an overwintering strategy to prevent the development of a metabolic acidosis during the long inactive dives observed during the season. As water temperature increases and aquatic P-O 2 decreases, R. leukops switches from facultative to obligate air-breathing, presumably because of the increased metabolic cost associated with aquatic respiration under summer conditions. Increases in mean surfacing time from winter to spring and summer are attributed to seasonal changes in behaviour possibly associated with foraging rather than to the physiological state of the turtle, given that no difference in median surfacing time among seasons was observed.

Using the flexibility index to compare batch and continuous activated sludge processes

This paper considers the question of which is better: the batch or the continuous activated sludge processes? It is an important question because dissension still exists in the wastewater industry as to the relative merits of each of the processes. A review of perceived differences in the processes from the point of view of two related disciplines, process engineering and biotechnology, is presented together with the results of previous comparative studies. These reviews highlight possible areas where more understanding is required. This is provided in the paper by application of the flexibility index to two case studies. The flexibility index is a useful process design tool that measures the ability of the process to cope with long term changes in operation.

Desenvolvimento sustent??vel: o desafio da admininstra????o p??blica brasileira nas dimens??es da relev??ncia social, da prud??ncia ecol??gica e da viabilidade econ??mica

Partindo do conceito de bem-estar social, definido em lei como de responsabilidade da administra????o p??blica, especialmente no que diz respeito ?? preserva????o dos recursos naturais para a manuten????o da decente qualidade de vida dos cidad??os, o artigo foi estruturado a partir do relat??rio de pesquisa de inicia????o cient??fica financiada pela Funda????o de Amparo ?? Pesquisa do Estado de S??o Paulo (Fapesp) e desenvolvido na Universidade Estadual de S??o Paulo (Unesp). Tal relat??rio objetivou investigar os par??metros de regularidade da administra????o p??blica, analisando-se a jurisprud??ncia dos tribunais. Foram evidenciadas irregularidades na atua????o da administra????o p??blica, constatando a desarticula????o da gest??o p??blica ao gerir as tr??s dimens??es que definem o desenvolvimento sustent??vel: a relev??ncia social, a viabilidade econ??mica e a prud??ncia ecol??gica. Foi poss??vel constatar com esta pesquisa que a administra????o p??blica brasileira d?? mais import??ncia para a quest??o econ??mica que ??s quest??es sociais e ambientais. Pudemos perceber que enquanto o meio ambiente ?? degradado e a sociedade prejudicada com a piora da qualidade de vida, o econ??mico vem sendo privilegiado constantemente. Sendo assim, evidenciaremos esse descaso propondo algumas mudan??as para a melhora da gest??o das tr??s dimens??es do desenvolvimento sustent??vel; por??m, em contrapartida, mostraremos a seriedade na atua????o dos ??rg??os colegiados ambientais e institui????es do poder p??blico, tais como o Minist??rio P??blico, que hoje atuam em parceria com a popula????o, crescentemente envolvida no processo mediante a pr??tica de den??ncias e reclama????es.

Clinton e a reinven????o do governo federal: o national performance review

O artigo analisa o National Performance Review (NPR), programa de reforma administrativa na gest??o do presidente Clinton, implementado em 1993, e que traduz o novo paradigma empreendedorialista proposto para o funcionamento da burocracia do governo federal americano. Na primeira parte s??o apresentados os princ??pios, objetivos e natureza da agenda, ressaltando-se as suas bases conceituais. Segue-se uma an??lise sobre a forma????o da agenda e a seq????ncia da sua implementa????o. A 3?? parte compreende uma vis??o da din??mica pol??tico-institucional, com destaque para as tens??es observadas entre o Legislativo e o Executivo, e o impacto destas nas mudan??as da agenda. Na ??ltima se????o, apresenta-se um painel emp??rico sobre alguns dos resultados em determinadas ag??ncias e departamentos do Governo, pretendendo-se oferecer contribui????es ao processo de reformas administrativas atualmente em curso no Brasil.

Determining factors of environmental management practices in portuguese local entities

Purpose: The aim of this paper is to analyse the development of environmental management practices by Portuguese local entities and their determining factors. Design/methodology/approach: The data were collected by sending a postal questionnaire. In order to measure the degree of development of environmental management practices an index of environmental management practices (EMPI) was developed, which reflects the extent to which a set of 16 environmental management practices have been implemented by the entities included in the sample. Four variables are considered in this study as possible factors that drive the development of environmental management practices by local entities, namely type of entity, size, proactive environmental strategy and Local Agenda 21 Findings: Results indicate the degree of development of environmental management practices in Portuguese local entities is low. Additionally, entity size, the adoption of proactive environmental strategies and the implementation of Local Agenda 21 are explaining factors of the degree of development of such practices. Originality/value: This study adds to the international research on environmental management in public sector by providing empirical data from a country, Portugal, where empirical evidence is still relatively limited.

Determining factors of environmental management practices in portuguese local entities

Purpose – The purpose of this paper is to analyse the development of environmental management practices by Portuguese local entities and their determining factors. Design/methodology/approach – The data were collected by sending a postal questionnaire. In order to measure the degree of development of environmental management practices, an index of environmental management practices (EMPI) was developed, which reflects the extent to which a set of 16 environmental management practices have been implemented by the entities included in the sample. In total, four variables are considered in this study as possible factors that drive the development of environmental management practices by local entities: type of entity; size; proactive environmental strategy; and Local Agenda 21. Findings – Results indicate the degree of development of environmental management practices in Portuguese local entities is low. Additionally, entity size, the adoption of proactive environmental strategies and the implementation of Local Agenda 21 are explaining factors of the degree of development of such practices. Originality/value – The paper adds to the international research on environmental management in the public sector by providing empirical data from a country, Portugal, where empirical evidence is still relatively limited.

Determinants of environmental disclosure in the annual reports of large companies operating in Portugal

Similarly to what has happened in other countries, since the early 1990s Portuguese companies have developed corporate environmental reporting practices in response to internal and external factors. This paper is based on empirical research directed to both the study of environmental reporting practices developed by Portuguese companies and the identification of the factors that explain the extent to which these companies disclose environmental information. This study focuses on the environmental disclosures made in the annual reports by a sample of 109 large firms operating in Portugal during the period 2002-04. Using the content analysis technique we have developed an index in order to assess the presence of the environmental disclosures in companies’ annual reports and their breadth. Based on the extant literature, several characteristics relating to firms’ attributes were selected and their influence on the level of environmental disclosure was tested empirically. The selected explanatory variables were firm size, industry membership, profitability, foreign ownership, quotation on the stock market and environmental certification. The results reveal that, in spite of the fact that the level of environmental information disclosed during the period 2002-04 is low, the extent of environmental disclosure has increased as well as the number of Portuguese companies that disclose environmental information. Moreover, the firm size and the fact that a company is listed on the stock market are positively related to the extent of environmental disclosure. This study adds to the international research on environmental disclosure by providing empirical data from a country, Portugal, where empirical evidence is still relatively unknown, extending the scope of the current understanding of the environmental reporting practices.

CORPORATE SOCIAL RESPONSIBILITY AND FINANCIAL PERFORMANCE: THE SPANISH CASE

ABSTRACT The enormous interest aroused by corporate social responsibility both in the academic and the business worlds forms the background for this study. Its objective is to analyze the relationship between corporate social responsibility and financial performance in view of the debate in the literature on the subject. The study focuses on a sample of Spanish companies taken from the IBEX 35 stock market index, using panel data methodology, which offers advantages in comparison to methodologies used in other studies. We analyzed the period from 2003 to 2010. Our findings suggest that there is no obvious relationship between corporate social responsibility and financial results, at least in the case of Spain.

Durability performance of concrete made with fine recycled concrete aggregates

Fine recycled aggregates are seen as the last choice in recycling for concrete production. Many references quote their detrimental influence on the most important characteristics of concrete: compressive and tensile strength; modulus of elasticity; water absorption; shrinkage: carbonation and chloride penetration. These two last characteristics are fundamental in terms of the long-term durability of reinforced or prestressed concrete. In the experimental research carried out at IST, part of which has already been published, different concrete mixes (with increasing rates of substitution of fine natural aggregates sand - with fine recycled aggregates from crushed concrete) were prepared and tested. The results were then compared with those for a reference concrete with exactly the same composition and grading curve, but with no recycled aggregates. This paper presents the main results of this research for water absorption by immersion and capillarity, chloride penetration (by means of the chloride migration coefficient), and carbonation resistance, drawing some conclusions on the feasibility of using this type of aggregate in structural concrete, while taking into account any ensuing obvious positive environmental impact.

Environmental and track perturbations on multiple pantograph interaction with catenaries in high-speed trains

The top velocity of high-speed trains is generally limited by the ability to supply the proper amount of energy through the pantograph-catenary interface. The deterioration of this interaction can lead to the loss of contact, which interrupts the energy supply and originates arcing between the pantograph and the catenary, or to excessive contact forces that promote wear between the contacting elements. Another important issue is assessing on how the front pantograph influences the dynamic performance of the rear one in trainsets with two pantographs. In this work, the track and environmental conditions influence on the pantograph-catenary is addressed, with particular emphasis in the multiple pantograph operations. These studies are performed for high speed trains running at 300 km/h with relation to the separation between pantographs. Such studies contribute to identify the service conditions and the external factors influencing the contact quality on the overhead system. (C) 2013 Elsevier Ltd. All rights reserved.

Economic, environmental and mixed objective functions in non-linear process optimization using simulated annealing and tabu search

Screening of topologies developed by hierarchical heuristic procedures can be carried out by comparing their optimal performance. In this work we will be exploiting mono-objective process optimization using two algorithms, simulated annealing and tabu search, and four different objective functions: two of the net present value type, one of them including environmental costs and two of the global potential impact type. The hydrodealkylation of toluene to produce benzene was used as case study, considering five topologies with different complexities mainly obtained by including or not liquid recycling and heat integration. The performance of the algorithms together with the objective functions was observed, analyzed and discussed from various perspectives: average deviation of results for each algorithm, capacity for producing high purity product, screening of topologies, objective functions robustness in screening of topologies, trade-offs between economic and environmental type objective functions and variability of optimum solutions.