1,721,021 research outputs found
Mathematical modelling of unsteady problems in thin aerofoil theory
No full textThe de-icing of aircraft wings by the injection of fluid through a slot in the leading edge of the wing is analysed. A review of current de-icing methods is presented and the semi-infinite slot-injection equation derived, which is a singular partial integro-differential equation. The Stefan condition is used to close the system. A discretisation of the equation is presented and the subsequent numerical results are analysed. The model is then revised to account for the retraction of the ice layer away from the slot. An asymptotic result for the thin ice layers is also presented.The problem of describing the motion of a thin, flexible membrane fixed at both ends (a 'sail') is then considered. The steady sail is analysed for the case of an inextensible sail and previous work on this topic is extended by using a discretisation of the singular integro-differential equation that is pertinent to the later analysis of the unsteady sail. An asymptotic expression for the eigenvalues of the system, defined as the values of the tension parameter for which the sail generates zero lift, is also presented. The problem is then extended to that of an extensible sail and numerical results are presented for both the sail with excess length and the membrane without slack.The case where the angle of incidence of the sail to the free stream is a prescribed function of time is then analysed. Previous work on this subject is extended to include the extensible sail and numerical results are presented. A linear stability analysis is then undertaken for both the extensible and elastic sails; the resulting quadratic eigenvalue problem is solved numerically and is in agreement with the numerical experiments.The trailing edge of the membrane is now permitted to move freely and thus the motion of a 'flag' is analysed. The inclusion of bending stiffness is found to be crucial to the stability properties of the flag. The steady equation of motion is numerically approximated for both a hinged flag and a flag that is clamped at the leading edge. The unsteady flag equation is then discretised and numerical results are presented. A linear stability analysis is performed, the conclusions of which are consistent with the numerical approximations of the unsteady flag equation
On the Problem of Authenticity of Information in Crimean Letters of Roman Pope Martin I
No full textК письмам ссыльного римского папы Мартина I, отправленным в 655 г. из Таврики в Константинополь, обращалось не одно поколение ученых, однако многое в них по-прежнему оставляет вопросы. Например, видны явные несоответствия между экономической и религиозной ситуацией, сложившейся в Херсоне к VII в., и ее характеристикой в письмах Мартина. Большинство историков полагают, что эта информация недостоверна и носит субъективный характер. Это связывается, как правило, с психологией ссыльного, преклонным возрастом, болезнями и прочими мотивами. По мнению автора статьи, письмам папы вполне можно доверять. Папа Мартин обладал необычайной силой духа, был религиозно-политическим лидером, не побоявшимся в борьбе за восстановление христианской истины восстать против императора и церковных иерархов. Он осознанно шел на унижения, мучения, смерть. Такой незаурядный человек вряд ли бы стал лукавить перед своими корреспондентами из-за куска хлеба, слишком это была мощная и цельная личность.Some generations of scholars referred to the letters of exile Roman Pope Martin I sent from Taurica to Constantinople in 655; however, there are still many questions there. For example, there are some obvious discrepancies between economic and religious situation formed in Cherson by the 7th century and the way Martin characterized it in his letters. Majority of historians believe that this information is inadequate and of subjective character. As a rule it is connected with psychology of the exile, his advanced age, illnesses and other motives. The author of the article thinks that Pope’s letter can be quite trusted. Pope Martin had a really strong spirit; he was a religious and political leader who in his struggle for restoration of Christian truth rose against the emperor and ecclesiastic hierarchs. He was consciously ready for humiliation, torment, death. Such an outstanding person could hardly be insincere with his correspondents because of a piece of bread; he was a very powerful and solid personality.Статья написана по материалам доклада, прочитанного автором в 2005 г. на международной конференции по церковной археологии в Национальном заповеднике «Херсонес Таврический»
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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