1,721,025 research outputs found
An experimental study on a novel reclaimed rubber compound for fiber-reinforced seismic isolators
No full textClassical rubber seismic isolators reinforced with steel shims are generally large, heavy, and expensive so rarely used for housing buildings. In the last few years, different technologies have been investigated and fiber reinforced elastomeric isolators (FREIs) demonstrated to be a promising option. Only by properly combining a lower cost of raw materials including the manufacturing process and an easier installation process can result in a cost-effective solution. In the present study, novel reclaimed-rubber FREIs reinforced with low cost fabrics were designed and manufactured. A reclaimed compound (RC) has been developed resulting in mechanical properties not significantly different from virgin rubber. Mechanical characterization of the RC showed a typical response of soft compound even if with lower tensile deformation capacity. RC adhesion with polyester and nylon fabrics was investigated in order to prevent debonding between different layers. In this regard recycled-rubber FREIs with polyester and nylon fabrics were manufactured and tested in unbonded configuration. The devices showed promising performance and paved the way for the development of low-cost and environmental-friendly seismic isolators for housing buildings
Influence of gaseous atmosphere during a thermal process for recovery of manganese and zinc from spent batteries
No full textThe aim of the work is the recovery by thermal treatment of manganese and zinc from a mixture of zinc-carbon and alkaline spent batteries, due to the different phase change temperatures of the metals. Activated charcoal, as a reductant of the zinc-bearing phases to metallic Zn, was added to the mixture that was heated in different atmospheres (air, nitrogen, carbon dioxide) at different temperatures and residence times. Characterization of the mixture and of the residues of thermal treatment was carried out by chemical analysis, thermogravimetric and differential thermal analysis, scanning electron microscope and X-ray diffraction and allowed to understand the mechanisms of reduction of zinc and to interpret the formation of different compounds during the process. Results show that recovery of 99% of Zn (grade 96%) at 1200 C and 97% of Zn (grade 99%) at 1000 C, are achieved in N2 at 30 min residence time. Recovery of Mn at 1200 C and 30 min residence time was around 90-100% (90% grade). These products are suitable, after refining, for production of new batteries or higher value-added products. The residue of the treatment, enriched in manganese oxide, could be used in the production of iron-manganese alloys. © 2013 Elsevier B.V. All rights reserved
Laboratory characterization of a reclaimed rubber compound for low-cost elastomeric isolators
No full textAlthough seismic isolation devices are effective in protecting structures during an earthquake, they are generally large, heavy, and expensive, making their application prohibitive for housing buildings. In the last few years, different strategies have been investigated to make seismic isolators cheaper and lighter for housing buildings in developing countries. Lower costs can be obtained at different scales: simplifying the installation process of devices, reducing energy consumption during manufacturing, and using recycled materials. Both weight and cost of isolators could be reduced by adopting flexible reinforcements in place of steel reinforcing plates, also allowing easier installation without bolted connections in unbounded configuration. Costs can be further reduced by replacing natural rubber with a recycled elastomer. It has been demonstrated that trying to give a second life to rubber is challenging, since devulcanization process, capable of breaking chemical bonds between rubber and sulphur, is highly polluting and requires high consumption of energy. In the present work, a recycled compound has been preliminary developed with mechanical properties not significantly lower than virgin rubber. Obtained parameters are satisfactory for use in unbounded isolators with flexible internal reinforcement where internal stresses are significantly reduced. In particular, a novel compound has been properly formulated in order to be lower cost in comparison to traditional one. Mechanical characterization of the material showed excellent properties including shear modulus and hardness similar to those of a soft rubber, even if a reduced ultimate deformation capacity is achieved. Furthermore, rubber adhesion with different fabrics has been investigated. Preliminary results are very promising and pave the way for the development of high-performance and low-cost rubber isolators
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Investigation on the status of rare earth elements contained in the powder of spent fluorescent lamps
Full text linkThe aim of this study is to examine the status of rare earth elements (REE) contained in the chemical compounds that make up the powder of spent fluorescent lamps, with a view of their recovery. The status of REE in the as-received powder, as well as in a few size-class fractions of it, has been established. This way, only those size-class fractions containing high REE concentrations can be considered in a recovery process. The investigation has been carried out using particle-size, chemical, TGA/DTA, XRPD, SEM-EDS and EMPA analyses. The last technique enabled to establish the status of REE within the lattice of the chemical compounds present in the powder. The fineness of the as-received powder and the higher REE concentration in the finest size-classes suggest that physical methods of separation should not be used to separate the REE-containing chemical compounds from each other. Leaching methods seem more suitable with a material of such size. © 2014 Elsevier B.V. All rights reserved
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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