1,720,958 research outputs found
Overview of the correlations between process parameters, microstructure and mechanical properties of reference castings and industrial demonstrators
No full textAmong the Aluminum casting processes, High Pressure Die Casting (HPDC) is an efficient, versatile and economic way for producing large number of components. Nevertheless, because of the elevated amount of rejected castings, it is important to know which are the main causes of defect formation and their effects on microstructure and mechanical properties. This paper presents, within the European MUSIC project, an overview of the preliminary correlations obtained studying both castings with defect generator geometry, referred to as Horse-shoe Reference Castings, and industrial demonstrators, referred to as Gear Box Housing. The deduced correlations between static mechanical properties and casting defects highlighted interesting trends in both cases
Application of cost model approach in HPDC contexts
No full textThe application of cost model approach in High Pressure Die Casting (HPDC) context has been
investigated by defining parametric analysis to identify the main sources of costs and the related impacts
on production processes. Results highlight the possibility for companies to better control industrial costs of
their products by examining in detail the different costs composing the HPDC process and verifying at the
same time the adherence to budget. Furthermore, particular attention was dedicated to attest that the
industrial cost of production significantly decreases when companies invest in quality controls during the
casting trial activities
Correlation process-microstructure-properties in High Pressure Die Casting Aluminum-Silicon alloys
No full textNowadays automotive industry and, in general, transportation one increasingly needs light components in order to reduce total weights and therefore limit harmful emissions and fuel consumption. The diecasting process, on one hand, is a versatile and high productivity process but, on the other, the amount of defects found in the castings is high and sometimes compromising the characteristics of the final product. Thus the reduction or, at least, the limitation of defects is capital in order to obtain much more reliable components, especially in the automotive field. For this reason it is important to know how the process works and investigate all the variables and parameters that may have consequences on the products and may compromise their mechanical characteristics, or worse may cause disease. This implies an increasingly detailed knowledge of process, castings’ microstructure and properties. The paper presents the results of analyses carried out on a reference casting specifically designed to generate as many kinds of defects as possible, at different levels of severity. The purpose of such a casting is to make the evaluation of defects quality level simpler, to generate defects of different degree through controlled variations of process parameters and to make the process monitoring easier and more effective by means of in-mold sensors. The paper also presents analyses and results carried out on industrial production diecastings, adopting the same way of proceeding optimized thanks to the reference casting mentioned above. The possible correlations between process parameters, microstructure and mechanical properties have been deduced analyzing all data collected through the equipments installed on the die casting machine, as in-mold pressure, temperature, plunger velocity/displacement sensors and thermo-cameras which monitor the temperature variation of both movable and fixed mold during the entire cycle, and also by means of analyses performed on the diecastings: X-ray NDT, metallographic inspection, tensile, three points bending, hardness tests and Scanning Electron Microscopy investigations. The main defects revealed are: porosities (caused both by the presence of gas or shrinkage during solidification), oxide films, incomplete filling of the casting and cracks, presence of segregation bands and ESCs, presence of flash and deformation of the casting. All of them have been detected, analyzed and related to one or more causes
Public survey on European foundries producing Aluminium alloy castings
No full textStaCast Project has been aimed at individuating by means of properly elaborated questionnaires and of dedicated surveys the specific standardization needs for what concerns Al alloys castings.
This activity is the direct consequence of the StaCast Project motivation, which is based on four key-issues.
1. The vast potential of Aluminium Alloys EU Foundry Industry strongly needs a coordinated set of Support Actions, in which a central role MUST be played by the elaboration of new and advanced Standards, particularly in the fields of Defects classification and Mechanical Design, which are mutually inter-related.
2. The use of a new EU Standard for the Classification of Casting Defects, which will help EU Aluminium alloys foundries at promptly performing corrective actions to reduce/eliminate defects, is becoming strategic. Such Standard will be also a useful “communication tool” among all the actors of the design and manufacturing chain.
3. The development of a new Standard on mechanical properties is strongly needed too, in order to correctly evaluate the effective mechanical potential of Al foundry alloys.
4. The design and manufacturing of Al alloys cast components NEED the availability of dedicated rules and guidelines, in order to correctly make use of the two new standards deriving from issues 2) and 3).
The four issues above need, first of all, to be confirmed by a dedicated survey to be carried out on an EU basis. This is the background which led to the set up of the Questionnaire, and to the answers elaboration which are described in the present Chapter
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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