1,721,102 research outputs found
Bondability of processed glass wafers
Get PDFThe mechanism of direct bonding at room temperature has been attributed to the short range inter-molecular and inter-atomic attraction forces, such as Van der Waals forces. Consequently, the wafer surface smoothness becomes one of the most critical parameters in this process. High surface roughness will result in small real area of contact, and therefore yield voids in the bonding interface. Usually, the root mean square roughness (RMS) or the mean roughness (Ra) are used as parameters to evaluate the wafer bondability. It was found from experience that for a bondable wafer surface the mean roughness must be in the subnanometer range, preferentially less than 0.5 nm. When the surface roughness exceeds a critical value, the wafers will not bond at all. However RMS and Ra were found to be not sufficient for evaluating the wafer bondability. Hence one tried to relate wafer bonding to the spatial spectrum of the wafer surface profile and indeed some empirical relations that have been found. The first, who proposed a theory on the problem of the closing gaps between contacted wafers was Stengl. This gap-closing theory was then further developed by Tong and Gosele. The elastomechanics theory was used to study the balance between the decrease of surface energy due to the bonding and the increase of elastic energy due to the distortion of the wafer. They considered the worst case by assuming that both wafers have a waviness, with a wavelength (lambda) and a height amplitude h, resulting in a gap height of 2h in a head to head position. This theory is simple and can be used in practice, for studying the formation of the voids, or for constructing design rules for the bonding of deliberately structured wafers. But it is insufficient to know what is the real area of contact in the wafer interface after contact at room temperature because the wafer surface always possesses a random distribution of the surface topography. Therefore Gui developed a continuous model on the influence of the surface roughness to wafer bonding, that is based on a statistical surface roughness model Pandraud demonstrated experimentally that direct bonding between processed glass wafers is possible. This result cannot be explained by considering the RMS value of the surfaces only, because the wafers used show a RMS value larger than 1 nm. Based on the approach exposed in reference six, a rigorous analysis of wafer bonding of these processed glass wafers is presented. We will discuss the relation between the bonding process and different waveguide technologies used for implementing optical waveguides into one or both glass wafers, and give examples of optical devices benefiting from such a bonding process
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
Interferometrical characterization of stress birefringence in germanium
No full textWe report on the characterisation of the refractive index homogeneity in large blanks of Czochralski-grown Germanium, for thermal imaging use. With a phase-measuring Twyman-Green interferometer working at 10.6 mu m, a map of the index of refraction with an accuracy better than 1 10(-5) can be obtained for blanks which do not exhibit high birefringence. Tn the other case, principal stresses in the disks can be determined through the effect of birefringence on the interferogram, if the stresses are distributed cylinder-symmetrically in the plane of the disk. Relations between stresses, transmittance, and electrical resistivity of the material are observed
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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