1,721,002 research outputs found
Enhancing thermal conductivity of amorphous polymers
Full text linkDepartment of Mechanical EngineeringHigh thermal conductivity of polymers is important to improve the functionality and reliability of products by efficiently dissipating heat in polymer products. Several studies have demonstrated that extended polymer chain conformation enhances the heat transfer in amorphous polymers. Here, we demonstrate that the tacticity of polymers alters the chain conformation in ionized polymers due to the difference in the coulombic interaction among the functional groups. Depending on their tacticity, polymers with the similar degree of ionization were observed to have significantly different cross-plane thermal conductivities, as high as 1.14 W/m???K in ionized atactic poly(acrylic acid)(PAA) and 0.69 W/m???K in ionized syndiotactic poly(methacrylic acid)(PMAA) but merely 0.55 W/m???K in ionized isotactic PAA and 0.48 W/m???K in ionized isotactic PMAA and atactic PMAA. Elastic modulus, viscosity data which affects the conformation of the polymer chain, suggested validating effect on the thermal conductivity of polymers.
In addition, we have systematically investigated the effect of annealing temperature on the cross-plane thermal conductivity of an amorphous natural bio-polymer. The results display a systematic increase in thermal conductivity (0.2 W/m???K to 1.3 W/m???K) with annealing temperature. This high thermal conductivity is mainly achieved by improving the crystallinity of polymer and low inter-planar spacing resulted to efficient phonon transport.clos
Analytical approach of natural convection in a radial heat sink with dissimilar fin dimensions
No full textDepartment of Mechanical Engineeringclos
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Effect of carbon concentration in TRGO-ethanol nanofluid on thermal performance in thermosyphon
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Convective performance investigation of electronics cooling system using Thermally reduced graphene oxide (TRGO)-H2O nanofluid
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No full textDepartment of Mechanical EngineeringCryotherapy or cryosurgery has been used for decades for various clinical purposes. During these treatments, skin is exposed to cold temperatures ranging from -150??C to -5??C depending on the desired clinical outcome, which can weaken the integrity of the skin and thereby increase infection risks such as pustular acne, abscesses, which may lead to a clinical complication requiring additional surgical repair. However, understanding the effect of cold temperatures on microbials having the skin infection is limited due to the lack of cooling technology that can precisely and rapidly control the cooling temperature. Here, we developed a cooling system that can address these absent information over temperature ranges of -30??C to -10??C with the cooling capability of maximum -10??C/sec. As the cooling rate increased, raised osmotic stress caused bacteria to die and under certain cooling conditions showed different tendencies depending on the target temperature. Also, the various cooling rates result in cell volume differences and the bacterial survival tendency was affected by the initial physical state of the cell before thawing. In summary, by controlling the three parameters (target temperature, cooling rate, and thawing rate) the results show that target temperature alone does not result in cell death and the cooling rate as well as thawing rate affect bacterial survival.clos
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
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