1,721,059 research outputs found
Implemenation of FEM and rapid prototyping in maxillofacial surgery
No full textThis paper investigates the opportunity of implementing FE simulations and rapid prototyping tecniques on titanium implant in maxillofacial surgery case based on osteotomy. Maxilla region was recorded by Cone Beam CT with high resolution and optimal radiation. Then, it followed the medical image reconstruction into 3D voxelized model. This model was converted both, to stl surface model for rapid prototyping, CAD modeling and FE mesh for simulation purposes with keeping good volume and dimensional consistency. Stl meshed surface was imported into CAD software, as initial 3d structure, which is used for parametric and customized design of implant. Since, the osteotomy is final application, it wassimulated the cutting and shifting of maxilla for proper correction by digital prototyping. Then, the fixation points for shifted maxilla were determined by surgeon to provide steady and tight joints between implanting screws and maxilla. Applied implant was given in initial standard flat configuration. Flat implant configuration was adapted by complex 3D bending in CAD software to be customized towards surface conformity of maxillofacial anatomy. By FE simulation in MSC Patran/Nastran, it was performed the stress analysis of implant with different thickness configurations and 3D bending, which provides the optimized implant model with best fit dimensions. Optimized implant model and corresponding body model were converted into physical models. RP model of maxilla was post-processed by cutting and boring to provide an adequate implant positioning according to digital prototypes. This approach facilitated the preparation of complex shaped implants in swept and lofted form, what had to be in high degree of conformity to anatomy surface. To approve a good practical opportunity, it was applied and tested in concrete surgery case of maxillofacial osteotomy
Comparing the accuracy of professional and consumer grade 3D printers in complex models production
No full textThis study aims at comparing the accuracy offered by professional and consumer grade 3D printing machines, inside a Fused Deposition Modelling (FDM) process of Additive Manufacturing (AM), in the realisation of complex models. It intends to verify, using an experimentally based approach, how much these two groups of 3D printers differ in terms of achieving complex geometry, surface quality and dimensional stability of additive models. Two consumer grade and professional 3D printers were selected and used for creating a complex model. Limits and benefits provided by each of them in engineering terms were investigated and reported. A religious building was used as a complex model, created by both 3D printers, scanned by reverse engineering technology, then processed by a software package for image processing. In this way, a comparison in models' accuracy was achieved. Results, graphically represented, show some notable differences between 3D printers in terms of accuracy and applicability. They also permit to make recommendations on practical usability of this technology
Sustainable small batch reproduction via additive manufacturing and vacuum casting: The case study of a rhinoceros toy figure
No full textThis paper aims at clarifying the relationship between two unconventional manufacturing processes, the additive manufacturing and the vacuum casting, as a sustainable way in developing prototypes and small batches, even in the presence of complex geometries. The rapid reproduction of a rhinoceros toy figure was used as case study. Starting from the 3D CAD model, acquired by reverse engineering techniques, additive manufacturing and vacuum casting processes permitted to realize its replicas. Complex functional parts in small series were manufactured with high precision, accuracy and enhanced surface finish. Furthermore, significant reductions in time and costs, both for development or production comparing to other technologies were highlighted
Introduction in production technologies
Get PDFIntroduction in Production Technology presents content as: Selection of Economical Production Technology; Technology of the Primer Processing and Forming; Metal Forming Technology; Metal Cutting Technology; Technology of Joining; Technology of metal heat treatments; Technology of surface protection; Processing of plastic materials; Ceramic Technology; Wood Processing Technology; Technology of semiconductors; Rapid Prototyping and Rapid Tooling; Technology of Recycling; Technology of Stone; Technology of Composite materials
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Combining additive manufacturing and vacuum casting for an efficient manufacturing of safety glasses
No full textThis paper presents the possibility of integration of modern techniques of
additive manufacturing and vacuum casting in the rapid manufacturing of
complex parts. The prototype of safety glasses was directly developed from
a CAD model, which is used as a main model for making moulds in a
vacuum casting process. The development stages, which include additive
production of glasses and the process of vacuum casting with the definition
of material components, preheating temperature, the forming of silicone
mould, the casting process, hardening and other parameters are presented
in this paper. It is proved that by using this technique it is possible to
produce complex functional parts quickly, with high precision, accuracy
and surface quality, while significantly reducing costs of development and
production compared to other similar Technologies
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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