1,720,955 research outputs found
Outside turning of commercially pure titanium alloys by minimum quantity lubrication
Get PDFM.Ing. (Mechanical Engineering)Abstract: Machining is a widely used class of industrial manufacturing operation, wherein cutting fluids play a vital role in terms of machining accurate dimensional quality objects due to their cooling, lubricant and chip removal abilities. Although certain advanced cutting fluids have changed the manufacturing industry for the better, there are some environmental concerns associated with some of these fluids. The use and disposal of cutting fluids may be costly and subjected to stringent government laws. Hence, the ever-growing research conducted on environmentally friendly cutting fluids that may lead to enhanced sustainable manufacturing. The aim of this investigation is therefore to investigate the viability of Minimum Quantity Lubrication (MQL) during machining of titanium alloys with specific focus on the commercially pure grades (Grade 2 & 4). This implies minimizing the consumption of harmful cutting fluids by exploring the use of environmentally friendly lubricants and sustainable lubrication techniques. In addition, minimizing the overall manufacturing cost by increasing the tool life, enhancing the work surface integrity, eliminating the need of post finishing operations and minimizing the energy consumption and cutting forces. An extensive literature review was conducted with the focus of machining titanium, effect of machining parameters on tool wear, surface roughness, cutting forces, cutting temperatures and power consumption. A related review was also conducted on the effect of MQL during the turning of titanium alloys. This was followed by the development of an experimental program, which comprised of the design of experiment, experimental setup, measurement and compilation of data. The experimental work was subdivided into; pilot experiments, main experiments and a comparative study. The aim of the pilot experiment was to determine the experimental protocol that was ultimately used in the main experiments. This included: exploring and solving all practical issues or challenges that may occur during the experimentation and optimizing the settings of MQL parameters in order to fix them during the main experiments. During the pilot experiment, the machining tests were conducted according to a 3-level and 3-factor 9 orthogonal array, at 3 different levels of MQL flow rate, nozzle distance and air pressure. The machining parameters; cutting speed, feed rate and depth of cut were kept constant at 125m/min, 0.2mm/rev and 1mm respectively. The Taguchi method and Grey relational optimisation was used to obtain the optimized parameters settings for Grade 4. The optimization showed that flow rate was the most significant parameter, followed by nozzle distance. Air pressure was the least significant. The analysis showed that the optimum MQL parameters for Grade 4 were: flow rate of 70ml/hr, nozzle distance of 30 mm and air pressure of 4 bar. A similar scheme was used to optimize the MQL parameters for Grade 2. The relative significance of the MQL parameters were similar to Grade 4. The analysis showed that the optimum MQL parameters for Grade 2 were: flow rate of 50ml/hr, nozzle distance of 30 mm and air pressure of 5 bar..
Complementary Machining – Machining Strategy for Surface Modification: A Review
Get PDFAll fabrication techniques utilized to manufacture metallic parts modify the surface integrity of the part. Complementary machining is a relatively recent machining strategy characterized by combining metal cutting and mechanical surface treatment. Typically, it implies that after conventional machining, the cutting insert is used reversely to modify the surface by local plastic deformation. To improve product performance, mechanical surface treatment is an additional phase in the manufacturing process chain that usually results in longer production times and higher costs. As a result, a variety of hybrid techniques have been created, such as complementary machining, which has the benefit of using conventional machine tools and their associated cutting tools. The study on complementary machining is reviewed in the article. The main focus is to assess the viability of complementary machining to modify surface integrity for enhanced properties by specifically establishing its effect on tool wear, surface roughness, microhardness, fatigue, microstructure, and residual stress state
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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