1,720,972 research outputs found
Failure analysis simulation of polymeric foam composite using ANSYS 15.0
No full textAccess is limited ti UniMAP community.Kajian ini menerangkan kesan multi tiubnano berdinding karbon (MWCNTs) ke atas sifat,
terutama sifat-sifat busa poliuretana tegar (PU) dihasilkan daripada polyol minyak sawit (POP)dan metilena diphenyl diisosianat (MDI). Busa komposit dalam nisbah 1: 1.1 (% Berat) yang
dicampurkan dan dikacau pada kelajuan 2000 rpm. Penambahan MWCNTs ke busa PU adalah
pilihan dari 0 wt% sehingga 2 wt %. Busa PU telah disediakan dengan menggunakan kaedah
tangan untuk menghasilkan busa poliuretana (PU) dan MWCNTs sahaja (PU/MWCNTs) dan
busa PU, multi tiubnano berdinding karbon serta kepingan aluminium (PU/MWCNTs/Al)
dengan resin epoksi sebagai pelekat untuk mengikat permukaan. Sifat-sifat dinilai adalah
kekuatan mampatan, ketumpatan dan modulus mampatan. Modulus mampatan busa PU
komposit dengan 0.5% ditambah MWCNTs menunjukkan nilai tertinggi 3.704 MPa untuk PU
- MWCNTs sahaja berbanding busa komposit lain. Bagi PU/MWCNTs/Al menunjukkan
modulus mampatan yang paling tinggi pada 1.0% ditambahkan dengan MWCNTs yang
bernilai 3.676 MPa. Ia telah dibuktikan dengan model menggunakan perisian ANSYS (versi
15.0) bahawa ketumpatan meningkat dengan penambahan 0.5% MWCNTs menjadi busa PU
ini. Meningkatkan jumlah MWCNTs dalam busa PU didapati meningkatkan modulus
mampatan untuk busa komposit. Walaupun, 1.0-2.0% berat MWCNTs ditambah di dalam busa
PU menjadi berkurangan modulus mampatan
Preparation and characterizations of palm oil based rigid nanocomposite polyurethane foam
No full textThe objective of this research is to study and analyze the basic and mechanical properties of polyurethane (PU) foam. PU foams were initially synthesized with reaction of natural oil polyol and isocyanate with ratio of 1:1.1 by weight. Water was used as the blowing agent and appropriate surfactant and catalyst were added to ensure better performance of final product. Cloisite 30B was added as filler and the percentages were varied from 1 to 5 wt%. The basic properties of polyurethane foams were determine, such as free rise density (FRD), foaming time and rheological index. Clay dispersion in polyurethane nanocomposites was investigated by X-ray diffraction method. Mechanical properties of foams were evaluated using uniaxial compression test where the energy absorption values were determined. Aluminium-polyurethane foam (Al-PU) sandwich composite was prepared and flexural test was carried out to examine the effect of skin attachment to PU foam. The results showed that with increasing nanoclay content resulted an increment in FRD to 74.6 kgm -3 , rheological index to 1.07gcm -1 and foaming by almost 133% for the addition of 5wt% nanoclay, respectively. Increasing in percentages of nanoclay filler in PU foam nanocomposite is also found to improve the absorption energy from 89J for pure PU foam to 118J for PU foam with 5wt% nanoclay. It was found that PU foam nanocomposite has better failure deformation as compared to sandwich composite with flexural extension that increase up to 9.4mm. However, flexural stress for sandwich composite are higher up to 3.6MPa. Furthermore, Al sheet acts as ductile skin to PU foam and prevent samples from rupture rapidly or prevent the formation of brittle fracture
Effects of cross head speed on properties and energy absorption of sandwich AL/PU-PTFE foam composite
No full textMaster of Science in Polymer EngineeringThis study to investigates the relations between cross head speed and the energy absorption of sandwich Al/PU/PTFE foam composite. The PU foam was prepared using the palm oil based polyol and isocyanate (MDI) with ratio of 1:1.1. The purpose addition of 2% PTFE filler for improve the properties of the foam such as resistance when load applied on
composite structure according to stiffness, strength, thermal stability and other structural properties. The flexural properties and energy absorption was study by using different cross head speed (5, 10, 15 and 20 mm/min) on PU/PTFE foam composite and sandwich foam composite. Moreover, the effect of PTFE on X-Ray diffraction, DSC, TGA and FTIR in PU foam composite were also investigated. It was found that PU/PTFE showed the lower crystallinity index as compared to PU foam due to the poor arrangement of PTFE. The DSC results indicate that adding of PTFE gives the higher heat stability even heated above
its crystalline melting temperature of 327 °C while PTFE also shows better thermal resistance than PU foam for TGA result. That means, PU/PTFE foam composite takes longer time to fully degrade than PU foam. Furthermore, the medium crosshead speed (10 and 15 mm/min) shows the higher flexural strength and flexural modulus for PU foam and PU/PTFE either in composite or sandwich foam. Meanwhile, the energy absorption of PU and PU/PTFE was increases due the lower cross head speed and this can delay the crack failure. In sandwich foam, the ductility of Al sheet used to increase the energy absorption
and improved the strength of sandwich foam
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
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