1,720,977 research outputs found
Characterization of gold particles in recoverable waste matrix
No full textOver the years there has been increasing interest in gold recovery from many different kinds of waste. Beneficiation processes, applied to gold recovery from old mine dumps, electronic scrap, dental scrap and jewellery waste have been extensively studied. To obtain good results, these processes need to start from a reliable physical characterisation of the occurrence of gold particles. This can be quite difficult due to the great heterogeneity of the matrix that holds the precious metal. The present work, applied to jewellery waste as a case study, shows that image processing techniques, applied to pictures obtained from optical microscopy or SEM, can offer good results. Nevertheless, information from chemical analyses, related to a size distribution, carried out by traditional wet-sieving, can be misinterpreted due to an overestimation of the influence of the associations between constituent particulate elements into waste. © 2001 Published by Elsevier Science Ltd. All rights reserved
Screening tests in the study of the iron oxide leaching by sucrose in sulphuric acid solutions using statistical methods
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
HOMOGENIZATION OF RAW MATERIAL BY PRODUCTION PLANNING AND STORAGE SYSTEMS.
No full textThis study deals with the development and utilization of computer models for evaluating the extent to which variability of raw material grades can be reduced from the deposit to the processing plant. The specific case of a cement works is examined. The deposit and the elementary quarrying operations were modeled for the medium and long-term planning of production with the objective of predicting grade variability of the flow stream in time. The feeds inferred from previous modellings were used for simulating storage operations. In particular, the storage process (linear stockpile, as an alternative, blending from various heaps) was modelled in order to select the main parameters of the process to minimize grade variations of the feed to mill. The ways followed for modelling the prehomogenization process are described. The homogenization performance and efficiency in the silo stage has also been studied and an estimate made of the distribution of residence time on the basis of input and output sampling
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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