1,720,956 research outputs found
Design and optimisation of a tipping silo semi-trailer by using innovative materials
No full textThis research reports the results of implementation of composite materials and the complete redesign of a tipping silo semi-trailer. The conventional semi-trailer, used for comparison, was designed based on a Feldbinder commercial model, while the innovative one has the same overall dimensions but a new geometry, while maintaining the same performance in terms of deflection and safety factor. The research involves sizing and verification of the results obtained using finite element software (Solidworks Simulation®) with different loading conditions. The main result is that the optimised solution has the lowest weight, with a reduction of about 28 % considering the same equipment and accessories mounted on the two solutions. The last part of the research concerns an estimate of economic investment containing the return on the initial investment and the reduction in fuel consumption by comparing the two solutions. Considering that the vehicle always carries the maximum (payload = 27,500 kg) and the overall weight reduction of about 1800 kg, there is a reduction in fuel consumption for the proposed solution. The return on investment for the new solution occurs between three/four years depending on the number of kilometres driven annually. Finally, the purpose of this paper is to create an example of a procedure for reducing the carbon footprint and the fuel consumption of vehicles by replace and redesign entire mechanical components, in this case industrial vehicles, that would be useful to follow and replicate for any specific case study and increase the eco-sustainability of industrial manufacturers
Jib crane lightweighting through composite material and prestressing technique
No full textThis research reports the results of both the implementation of innovative materials, such as composite material, and the application of the prestressing technique through appropriate tie-rods, for crane construction. The novelty lies in the introduction of both factors in order to reduce and limit the vertical deflection, while also reducing the cross section, which is the main constraint at the machine design phase. In this way, to limit the load-induced deflection of the crane, a constant external action is applied that induces a deflection opposite to that induced by the load. In particular, the object of this research is a jib crane with dimensions 4000x5000 (height and length in mm) with a load capacity of 4905 N. The research involves analytical dimensioning followed by verification of the results obtained using finite elements software (Ansys®). The parameters adopted for sizing, both the boom and the column, are the maximum displacements and safety coefficients concerning both maximum stresses and buckling phenomena. The main result is that the composite crane has the lowest weight: approximately 29 % and 21 % of the weight of the corresponding non-prestressed steel crane, for non-prestressed and prestressed composite configurations, respectively. The last part of the research concerns the construction methods for building cranes, in particular the implementation of the composite solution
Development and Design of an Innovative and Lightweight Reconnaissance Rover Using Composite Materials
No full textModern planetary rovers are based on aluminum chassis, but thanks to carbon fiber composites, the weight of such mobility platforms can be dramatically lowered. This paper describes the design of a 6-wheeled rover with a rocker-bogie suspension, adopting carbon fiber laminates and short-fiber-reinforced polymers. This last feature is an innovative approach that fits well with the use of additive manufacturing, allowing for both highly optimized parts and rapid fabrication of spares in future manned missions on the Lunar surface. The structural design was validated against a set of boundary conditions (static analyses) and requirements of launch and space environments (dynamic analyses) as prescribed by European Cooperation for Space Standardization standards. The composite rover was designed to lighten the structure itself and increase the payload-to-total-mass ratio: the composite solution offers a ratio three times higher than the typical rover (ratio from 0.12 to 0.38)
Failure analysis of a pair of failed chain links
No full textThe failure of a pair of metal chains during a towing operation in a particularly aggressive environment is examined. Evaluation of the cause of failure is carried out through visual observation, optical and scanning electron microscope analyses of various surfaces, including fracture surfaces, in combination with hardness and tensile tests. Visual examination revealed a high reduction in the resistant section near the contact zones between contiguous links, where the chains then failed. The chemical composition and percentage of elements present on the surface showed a high presence of corrosion products. The main cause of the chain link failure was due to corrosive wear, which markedly wore down the chain by reducing its resistant section resulting in overloading of the remaining net section area of the chain. Corrosive wear also removed the case-hardened layer induced by carbo-cementation. In order to assess the effect of corrosive wear power, an analytical evaluation was proposed. This method, although approximate, succeeds in assessing the reduction in chain strength induced by corrosive wear. Better inspection and maintenance would have allowed for early detection of the presence of the corrosive wear phenomenon, while a metal material with greater resistance to corrosion would certainly have postponed and/or prevented the manifestation of this problem, ensuring a longer service life. In this way, the initially planned safety coefficient of 2, in relation to the static breaking load, can also be reduced
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
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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