1,720,960 research outputs found
Wavelet Transform Based Damage Detection in a Plate Structure
No full textAbstractA 2-dimensional wavelet transform algorithm employing isotropic Pet Hat wavelet is used to locate the area of damage in a numerically simulated aluminium plate model. To study the advantages and limitations of proposed method, signals of vibrational mode shapes of the plate are reduced by integer numbers to study the performance of algorithm at various sensor densities. Results suggest that the lowest scale of selected wavelet function yields the best damage identification results with a damage location likelihood of more than 98%
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
Nieliniowa analiza statyczna konstrukcji przekładkowej z wypełnieniem kratownicowym (typu sandwich) wg. trzypunktowego schematu zginania
No full textAn analysis of sandwich beams with truss core is an important issue in many fields of industry such as civil engineering, automotive, aerospace or maritime. The objective of the present study is a nonlinear static response of sandwich beams subjected to the three-point bending test configuration. The beams are composed of two parent components: upper and lower laminated face sheets (unidirectional tape) and a pyramidal truss core manufactured by means of 3D printing. A polyamide filament strengthened with chopped carbon fibres – CF-PA-12 is used for the core development. The both, experimental and numerical analyses are presented. A detailed numerical model of the sandwich beam was developed in Abaqus software. The numerical model considers modelling of the adhesive joint with an additional layer of material placed between the parent components of the beam. A continuum hybrid solid shell elements were used to model the adhesive layer. In addition, a special care was taken to use an appropriate material model for the CF-PA-12 filament. To do so, the uniaxial tensile tests were performed on 3D printed samples. Having acquired the test data, a hyperelastic material model was evaluated based on a curve fitting approach.Kompozytowe struktury przekładkowe z wypełnieniem kratownicowym (typu sandwich) są wytwarzane w postaci płyt, belek, oraz powłok cylindrycznych. Kompozyty te zbudowane są głównie z dwóch materiałów macierzystych, tj. okładzin zewnętrznych w postaci cienkich płyt lub taśm oraz wypełnienia wewnętrznego o geometrii przestrzennej kratownicy. Struktury te mogą być traktowane jako elementy konstrukcyjne ze względu na ich znakomite wskaźniki sztywności i wytrzymałości w stosunku do masy. Ponadto, ich komórkowa budowa poprawia możliwości wentylacyjne oraz umożliwia prowadzenia instalacji pomiędzy poszczególnymi komórkami całej struktury. Powoduje to, że oprócz funkcji nośnych, struktury te stanowią również elementy funkcjonalne. Zalety struktur przekładowych przyczyniły się do zintensyfikowania badań naukowych w zakresie analiz statycznych. Jako, że struktury te stanowią kompozyt, ich właściwości mechaniczne przyjmują różnorodne cechy w zależności od schematu obciążenia. Pociąga to za sobą dodatkowe trudności w procesie modelowania takich konstrukcji ze względu na bardzo szeroki zakres materiałów stosowanych do ich budowy oraz połączeń między nimi. Różnorodność ta przejawia się już w doborze okładzin zewnętrznych, które są wykonywane z trzech grup materiałów, tj. metali lub ich stopów (np. aluminium), laminatów warstwowych (np. laminaty włókniste), materiałów organicznych (np. sklejka). Kolejną kwestią jest materiał stosowany na budowę komórkowej warstwy wypełnienia. Ograniczając się do jednej geometrii tej warstwy, tj. do postaci przestrzennej kratownicy, materiałami stosowanymi do ich budowy, poza wyżej wspomnianymi, są polimery wytwarzane techniką przyrostową. Niestety zdecydowana większość opracowań naukowych pozostawia bez komentarza kwestie modelowania oraz nośności połączeń adhezyjnych w powyższych strukturach. W bieżącej pracy założono przeprowadzenie analizy statycznej wg schematu trzypunktowego zginania. W procesie budowy modelu numerycznego uwzględniono połączenia klejone pomiędzy elementami macierzystymi belki poprzez wprowadzenie dodatkowego materiału adhezyjnego. Do modelowania polimerowego wypełnienia kratownicowego (CF-PA-12) zastosowano hipersprężysty model materiału. Parametry sprężyste modelu materiałowego oszacowano na podstawie statycznej próby rozciągania próbek wytworzonych techniką przyrostową. Weryfikacja poprawności opracowanego modelu MES przeprowadzona została na podstawie porównania obliczeń numerycznych z przeprowadzonymi pomiarami laboratoryjnymi, uzyskując dużą zbieżność wyników. Przeprowadzone badania pozwoliły na opracowanie modelu numerycznego belki przekładkowej z uwzględnieniem warstwy adhezyjnej. Wykony model numeryczny belki może służyć do prognozowania jej odpowiedzi statycznej. Zastosowanie kontynualnych elementów skończonych pozwoliło na znaczną redukcję ilości elementów po grubości warstwy adhezyjnej
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
Mode shape curvature squares method for crack detection in railway prestressed concrete sleepers
Get PDFThis unprecedented study aims to demonstrate the potential to locate crack damage and severity in full-scale railway prestressed concrete sleepers. The dynamic mode shape curvature squares method has been utilised. This approach adopts structural deflection shapes extracted from experimental modal analysis using an impact excitation. The railway concrete sleepers are exposed to the first crack and 1.5 times above the first-crack loads using experimental setup in accordance with the British Standard (for benchmarking purpose). It is found that the first cracking of the sleepers has caused non-significant stiffness reduction of the structural component evidenced from the fact that the natural frequency shifts are only few percent and no visible differences in deflection mode shapes are observed. In addition, the mode shape curvature alone cannot indicate the crack establishment in the railway sleepers. However, a relatively sparse wireframe for deflection shapes enable the plausible density of sensor grids that can be further analysed for damage detection. In this paper, the curvature square approach has been developed to quantify and locate the damage in the railway sleepers. The standardized damage index distributions and subsequent thresholding with different levels of confidence of damage localization have been firstly developed to enhance the accuracy of crack localization. It is found that accurate locations of cracks mostly in the mid span of the sleepers can be reasonably detected in accordance with the actual crack measurements from the experimental data. The novel insight into this approach can enhance the new development of on-board technology for railway sleeper crack detection using operational modal signals
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
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