1,721,051 research outputs found
Additive or Conventional Manufacturing as spare parts manufacturing technology: the impact of qualification tests
No full textAdditive manufacturing (AM) has recently emerged as a potential breakthrough technology in the world of spare parts management. Thanks to its characteristics, it can enable the production of spare parts with very low production lead time, with considerable impacts in terms of inventory levels. Some researchers have recently focused on the topic, trying to understand whether it is convenient to produce spare parts in AM or in Conventional Manufacturing (CM) techniques. However, all these works neglect a crucial aspect. Spare parts, before being utilized, need to be qualified from certified entities. The qualification requirements vary depending on the criticality of the spare parts, but they are all associated with non-negligible costs, which however have been completely neglected so far. In this work, to overcome this gap we develop a mathematical model that can support managers and practitioners in choosing the most convenient manufacturing technology (i.e. AM or CM) considering for the first time the qualification costs. The model proposed has been applied to a real case study to demonstrate its applicability. Copyright (c) 2023 The Authors
Special Issue “Advanced Digital Technologies for the Integration of Production and Maintenance”
Full text linkOn the corrosion, stress corrosion and cytocompatibility performances of ALD TiO2 and ZrO2 coated magnesium alloys
Full text linkMagnesium alloys are increasingly studied as materials for temporary implants. However, their high corrosion rate and susceptibility to corrosion-assisted cracking phenomena, such as stress corrosion cracking (SCC), continue to prevent their mainstream use. Recently, coatings have been considered to provide an effective solution to these issues and researchers have focused their attention on Atomic Layer Deposition (ALD). ALD stands out as a coating technology due to the outstanding film conformality and density achievable, and has shown encouraging preliminary results in terms of reduced corrosion rate and reduced SCC susceptibility. Here, we contribute to the ongoing interest in ALD-coated Mg alloys, providing a comprehensive characterisation of the effect of 100 nm thick ALD TiO2 and ZrO2 coatings on the corrosion behaviour and SCC susceptibility of AZ31 alloy. Moreover, we also investigate the effect of these coatings on the induced biological response. Our results suggest that the ALD coatings can improve the corrosion and SCC resistance of the Mg alloy, with the ZrO2 ALD coating showing the best improvements. We suggest that the different corrosion behaviours are the cause of the cytocompatibility results (only the ZrO2 ALD coating was found to meet the demands for cellular applications). Finally, we leverage on considerations about the coatings’ wettability, electrochemical stability and surface integrity to justify the different results
A methodological framework to integrate motion capture system and virtual reality for assembly system 4.0 workplace design
Full text linkNowadays new products are required more and more often. Since a certain product is assembled only on a specific Assembly System (AS), a new AS has to be designed every time a new product is developed. Similarly, since an AS is constituted by one or more workplaces, new workplaces need to be designed every time a new product is developed. However, this is not feasible considering the time- and resource-consuming AS workplace design procedures currently used (e.g., physical mock-ups and computer-aided systems). New solutions have thus emerged to accelerate the AS workplace design procedures, especially since the advent of Industry 4.0 (I4.0) technologies. Specifically, the combined use of motion capture (mocap) systems and Virtual Reality (VR) has been considered very promising, with many researchers showing its potential. However, to the best of the authors’ knowledge, none of them suggests a clear methodology to follow when designing AS workplaces using the mocap system and VR. In this paper, we thus aim to fill this gap by developing a methodological framework that describes in detail the different steps to be followed. Moreover, the methodological framework has been developed in such a way that both productivity and Occupational Safety and Health (OSH) considerations are included. Furthermore, it encompasses the current ageing workforce scenario by explicitly including the ageing workforce's main characteristics (reduced flexibility and strength and greater experience of older operators). A simple but representative case study has then been carried out to demonstrate how to use the methodological framework and to prove its validity
Mg and its alloys for biomedical applications: Exploring corrosion and its interplay with mechanical failure
Full text linkThe future of biomaterial design will rely on temporary implant materials that degrade while tissues grow, releasing no toxic species during degradation and no residue after full regeneration of the targeted anatomic site. In this aspect, Mg and its alloys are receiving increasing attention because they allow both mechanical strength and biodegradability. Yet their use as biomedical implants is limited due to their poor corrosion resistance and the consequential mechanical integrity problems leading to corrosion assisted cracking. This review provides the reader with an overview of current biomaterials, their stringent mechanical and chemical requirements and the potential of Mg alloys to fulfil them. We provide insight into corrosion mechanisms of Mg and its alloys, the fundamentals and established models behind stress corrosion cracking and corrosion fatigue. We explain Mgs unique negative differential effect and approaches to describe it. Finally, we go into depth on corrosion improvements, reviewing literature on high purity Mg, on the effect of alloying elements and their tolerance levels, as well as research on surface treatments that allow to tune degradation kinetics. Bridging fundamentals aspects with current research activities in the field, this review intends to give a substantial overview for all interested readers; potential and current researchers and practitioners of the future not yet familiar with this promising material. © 2017 by the authors. Licensee MDPI, Basel, Switzerland
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
- …
