1,721,106 research outputs found
Crack propagation behavior in TiAl-Nb single and Bi-PST crystals
No full textThe fracture toughness of directional solidified Ti-(45,47)Al-3Nb, Ti-(45,47)Al-3Nb-0.2Si-0.1C, Ti-(45,47)Al-3Nb-0.3Si-0.2C type I alloys and their contribution to crack growth resistance of TiAl-Nb alloys were studied using PST (polysynthetically twinned) crystals produced by directional solidification in FZ (floating zone) furnace. Lamellar orientations in the individual colonies are described using two angles defined with respect to the notch orientation: an in-plane kink angle and a through-thickness twist angle. Therefore, lamellar misorientation across an individual colony boundary is quantified as differences in these angles across the boundary. Crack growth resistance in colony boundary was identified by three-point bend test and crack advance was monitored by interrupted in situ test. From three-point bend test, it was found that the colony boundary could offer significant resistance to crack growth under large twist angle difference. Fracture toughness of type I specimens (in which crack propagates against lamellae boundaries) of the alloys decreased slightly with increasing Si and C contents and increased rapidly with decreasing Al content. The toughness for type I specimens was controlled by alpha(2)-alpha(2) spacing in which the delamination-type separation occurred. Compared to 47Al alloys, alpha(2)-alpha(2) spacing in 45Al alloys increased by decreasing Al content, therefore, fracture toughness increased rapidly. These results are discussed and the ability to improve toughness by changing Al content, Si and C addition in TiAl-Nb alloys produced by directional solidification is suggested. (C) 2007 Elsevier Ltd. All rights reserved
Effect of nitrogen on the mean lamellar thickness of fully lamellar TiAl alloys
No full textThe effect of nitrogen addition in the 0-1.0 at.% range on the mean lamellar thickness of a fully lamellar TiAl alloy (Ti-48.5Al-1.5Mo) has been studied. Mean lamellar thickness first decreases with 0.3 at.% N addition but then increases with further increase in N level in the alloy. The increase in lamellar spacing for N levels between 0.3 and 1.0 at.% is attributed to the formation of Ti2AlN nitrides and the consequent change in Al level in the matrix. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved
Microstructure and toughness of nitrogen-doped TiAl alloys
No full textThe effect of nitrogen doping of TiAl in the nitrogen levels up to 1.0 at.% N (0.3, 0.5,and 1.0%) on microstructure, compressive yield strength and fracture toughness has been examined. The mean colony size decreases with increasing nitrogen content in the alloy. The lamellar morphology is preserved in the 0.3 at.% N alloy and a uniform, fine lamellar spacing is recognized. There was no evidence of nitrides being present. In the 0.5 at.% N alloy, the lamellar spacing is relatively coarser, there are clear indications of the destabilization of the lamellar morphology both within the colonies and at colony boundaries, and there are more or less continuous films of nitride precipitates along certain lamellar interfaces. In addition, fine nitride precipitates are present often on dislocations within the equiaxed gamma grains that result from the destabilization of the lamellar structure adjacent to colony boundaries. These effects are significantly more pronounced in the 1.0 at.% N alloy, and in addition, coarse nitride precipitates occur frequently at colony boundaries. The effects of these microstructural modifications on ambient temperature compressive yield stress and notched-bend fracture toughness have been examined and the observations are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved
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
Introduction: Sustainability and development: Perspectives from India
No full textWith an impressive economic growth rate averaging around 7.0 percent during 2003–2004 to 2019–2020, India is currently the fifth largest economy in the World. The growth has enabled India to make remarkable progress in absolute poverty reduction and make significant strides in its progress towards achieving Sustainable Development Goals. However, several crucial sectors of importance from the Human Development perspective, namely, health and education, continue to receive lower than desired level of attention. Over the period 2014–2015 to 2019–2020, the expenditure on education sector marginally improved from 2.8 to 3.1 percent of the gross domestic product (GDP), but remained well below the desired level of about 6 percent of GDP. The health sector over the same period improved its share from 1.2 to 1.6 percent of GDP, but the allocation in this sector too stayed below the recommendations of the 15th Finance Commission. The manifestation such under-allocation is reflected through worrying trends across various human development dimensions including close to 35 percent of the children in India suffering from malnutrition. It is also reflected in continuing under performance of India in the global human development index rankings. Equally concerning is India’s below par achievement in terms of gender equality. As per the World Economic Forum’s latest Global Gender Gap Report 2021, India slipped as many as 28 positions and ranked 140 among 153 countries. Among South Asian countries, only Pakistan and Afghanistan had lower achievements than India in bridging the gender gap. The gender gap is contributed among other dimensions by low levels of female labor force participation rates and significant gap between men and women in terms of the income earned. Further, the growing population, growing urbanization and higher consumption needs pose serious concerns regarding the sustainability of the impressive economic growth. The Covid-19 pandemic aggravated the already decelerating economic growth and pushed the GDP growth rate to negative digits. This has also put constraints on fiscal space to shape-up fast and effective recovery. The economic recovery is expected to take time and the impact of pandemic will be felt more acutely on the informal sector. All this will further hamper India’s developmental aspirations.Full Tex
- …
