1,721,058 research outputs found
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
Diagnostic tools for HVOF process optimization:Dissertation
No full textIn the thermal spray process the coating is built up from lamellas formed by rapid solidification of the melted or semi-melted droplets attached to the substrate. A typical structure for the coating is a pancake-like lamellar structure, where the flattening stage and adhesion between the lamellas, together with the coating material itself, define the main properties of the coating. Thermal spray coatings are often applied for better corrosion and wear resistance. Therefore, low porosity and good adhesion are desired properties for the coating. High velocity processes - especially HVOF (High velocity oxy-fuel) spraying - are the most potential methods for producing a good adherent coating with low porosity. From a scientific point of view, particle velocity and particle temperature, together with substrate temperature, are the main parameters affecting the deposit formation. They determine the deposit build-up process and deposit properties. Particle velocity and temperature affect the deposit efficiency as well as the microstructure. The aim of this work was to show the workability of diagnostic tools in the HVOF process. The focus was on first order process mapping, including on-line diagnostics and single splat studies. Nanocrystalline alumina composites and quasicrystals were selected, two materials that are complex to spray. With both materials the melting state of the particles must be well optimized in order to produce dense, well-adhered coating without unwanted changes in coating phase structure. The main focus was on the HVOF spraying of alumina. The target was to obtain a systematic understanding of the influence of the process conditions on the microstructure development in HVOF alumina coatings. Conventional limits of gas ratios and flows were exceeded to obtain a wide velocity-temperature range. The study aimed to produce information for a first order process map, and was carried out at a much deeper level than previously reported. Propylene and hydrogen as fuel gases were compared, and other variables, such as total gas flow rate, fuel gas/oxygen ratio, and standoff distance were also varied. The obtained data was applied for nanostructured alumina composite coatings, and the effect of the process conditions was compared on the obtained coating microstructure and properties. On-line diagnostic measurements, in which particle temperatures and velocities in the flame can be measured, were performed. The main work was carried out for alumina by using a DPV-2000 system. Two clear regions of different temperature and velocity arise from the use of different fuel gases. Single splat studies correlated well with the obtained coating properties, and a first order process map for alumina was created showing the window for the spray parameters producing best coating quality plotted against coating hardness and abrasive wear resistance. It was shown that diagnostic results can be correlated with the coating microstructure and coating properties in HVOF spraying. It was also demonstrated that the coating properties and coating quality can be improved by optimizing and carefully selecting the spray parameters
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
Diagnostic tools for HVOF process optimization:Dissertation
No full textIn the thermal spray process the coating is built up from lamellas formed by rapid solidification of the melted or semi-melted droplets attached to the substrate. A typical structure for the coating is a pancake-like lamellar structure, where the flattening stage and adhesion between the lamellas, together with the coating material itself, define the main properties of the coating. Thermal spray coatings are often applied for better corrosion and wear resistance. Therefore, low porosity and good adhesion are desired properties for the coating. High velocity processes - especially HVOF (High velocity oxy-fuel) spraying - are the most potential methods for producing a good adherent coating with low porosity. From a scientific point of view, particle velocity and particle temperature, together with substrate temperature, are the main parameters affecting the deposit formation. They determine the deposit build-up process and deposit properties. Particle velocity and temperature affect the deposit efficiency as well as the microstructure. The aim of this work was to show the workability of diagnostic tools in the HVOF process. The focus was on first order process mapping, including on-line diagnostics and single splat studies. Nanocrystalline alumina composites and quasicrystals were selected, two materials that are complex to spray. With both materials the melting state of the particles must be well optimized in order to produce dense, well-adhered coating without unwanted changes in coating phase structure. The main focus was on the HVOF spraying of alumina. The target was to obtain a systematic understanding of the influence of the process conditions on the microstructure development in HVOF alumina coatings. Conventional limits of gas ratios and flows were exceeded to obtain a wide velocity-temperature range. The study aimed to produce information for a first order process map, and was carried out at a much deeper level than previously reported. Propylene and hydrogen as fuel gases were compared, and other variables, such as total gas flow rate, fuel gas/oxygen ratio, and standoff distance were also varied. The obtained data was applied for nanostructured alumina composite coatings, and the effect of the process conditions was compared on the obtained coating microstructure and properties. On-line diagnostic measurements, in which particle temperatures and velocities in the flame can be measured, were performed. The main work was carried out for alumina by using a DPV-2000 system. Two clear regions of different temperature and velocity arise from the use of different fuel gases. Single splat studies correlated well with the obtained coating properties, and a first order process map for alumina was created showing the window for the spray parameters producing best coating quality plotted against coating hardness and abrasive wear resistance. It was shown that diagnostic results can be correlated with the coating microstructure and coating properties in HVOF spraying. It was also demonstrated that the coating properties and coating quality can be improved by optimizing and carefully selecting the spray parameters
Diagnostic tools for HVOF process optimization
Get PDFIn the thermal spray process the coating is built up from lamellas formed by rapid solidification of the melted or semi-melted droplets attached to the substrate. A typical structure for the coating is a pancake-like lamellar structure, where the flattening stage and adhesion between the lamellas, together with the coating material itself, define the main properties of the coating. Thermal spray coatings are often applied for better corrosion and wear resistance. Therefore, low porosity and good adhesion are desired properties for the coating. High velocity processes – especially HVOF (High velocity oxy-fuel) spraying – are the most potential methods for producing a good adherent coating with low porosity.
From a scientific point of view, particle velocity and particle temperature, together with substrate temperature, are the main parameters affecting the deposit formation. They determine the deposit build-up process and deposit properties. Particle velocity and temperature affect the deposit efficiency as well as the microstructure.
The aim of this work was to show the workability of diagnostic tools in the HVOF process. The focus was on first order process mapping, including on-line diagnostics and single splat studies. Nanocrystalline alumina composites and quasicrystals were selected, two materials that are complex to spray. With both materials the melting state of the particles must be well optimized in order to produce dense, well-adhered coating without unwanted changes in coating phase structure.
The main focus was on the HVOF spraying of alumina. The target was to obtain a systematic understanding of the influence of the process conditions on the microstructure development in HVOF alumina coatings. Conventional limits of gas ratios and flows were exceeded to obtain a wide velocity-temperature range. The study aimed to produce information for a first order process map, and was carried out at a much deeper level than previously reported. Propylene and hydrogen as fuel gases were compared, and other variables, such as total gas flow rate, fuel gas/oxygen ratio, and standoff distance were also varied. The obtained data was applied for nanostructured alumina composite coatings, and the effect of the process conditions was compared on the obtained coating microstructure and properties.
On-line diagnostic measurements, in which particle temperatures and velocities in the flame can be measured, were performed. The main work was carried out for alumina by using a DPV-2000 system. Two clear regions of different temperature and velocity arise from the use of different fuel gases. Single splat studies correlated well with the obtained coating properties, and a first order process map for alumina was created showing the window for the spray parameters producing best coating quality plotted against coating hardness and abrasive wear resistance.
It was shown that diagnostic results can be correlated with the coating microstructure and coating properties in HVOF spraying. It was also demonstrated that the coating properties and coating quality can be improved by optimizing and carefully selecting the spray parameters.reviewe
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
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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