31 resultados para Bois de tension

em Deakin Research Online - Australia


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This article is concerned with interactions between the natural and the human sciences. It examines a specific late 19th-century episode in their relationship and argues that the schism between the two branches of knowledge was due to cognitive factors, but consolidated through the social dynamics of institutionalized disciplines. It contends that the assignment of a social function to the human sciences to compensate for the self-destructive tendencies inherent in the technological society was expressed even by those, at the end of the 19th century, who were fervent advocates of a science- and technology-driven modernization.

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This article examines the notion of the 'scientist as a moral person' in the light of the early stages of the commodification of science and the transformation of research into a big enterprise, operating on the principle of the division of labour. These processes were set in train at the end of the 19th century. The article focuses on the concomitant changes in the public persona and the habitus of scientific entrepreneurs. I begin by showing the significance of the professional networks that were built up and maintained to further a group's research ideas and the careers of its members, thus demonstrating one condition on which depended their practice of science and their ability to earn a living. This leads to a characterization of the changing styles of work, thought and life, and to a consideration of public perceptions and of the ways in which a new self-image of scholarship and science was fashioned. A critical discussion of the public role of these mandarin scientists follows in order to highlight the strains created by the commodification of science at a time of international tensions and conflicts, when shared beliefs in scholarly cosmopolitanism were subverted by appeals to science and scholarship to work in the service of one's own nation as its 'courtiers'. Various considerations of peculiar analogies between national styles of research and the style of social organization are then noted. In the final section, the article queries the long-term impact of these developments on the ideal of the scientist as a 'moral person'. Taking a cue from Max Weber and pursuing reflections by Zygmunt Bauman on 'science moralized', I argue that the emergence of a type of 'specialists without spirit' was an unintended but fatal consequence of the changes in research practices promoted by scientific entrepreneurs such as Du Bois-Reymond. I conclude that the temptation to sever the ties to a general ethos of civil virtues lay in the rationalization, specialization and potential de-humanization of the objectifying scientific outlook once advocated for its efficiency.

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Yarn tension is a key factor that affects the efficiency of a ring spinning system. In this paper, a specially constructed rig, which can rotate a yarn at a high speed without inserting any real twist into the yarn, was used to simulate a ring spinning process. Yarn tension was measured at the guide-eye during the simulated spinning of different yarns at various balloon heights and with varying yarn length in the balloon. The effect of balloon shape, yarn hairiness and thickness, and yarn rotating speed, on the measured yarn tension, was examined. The results indicate that the collapse of balloon shape from single loop to double loop, or from double loop to triple etc, lead to sudden reduction in yarn tension. Under otherwise identical conditions, a longer length of yarn in the balloon gives a lower yarn tension at the guide-eye. In addition, thicker yarns and/or more hairy yarns generate a higher tension in the yarn, due to the increased air drag acting on the thicker or more hairy yarns.

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To quantify the frictional behaviour in sheet forming operations, several laboratory experiments which simulate the real forming conditions are performed. The Bending Under Tension Test is one such experiment which is often used to represent the frictional flow of sheet material around a die or a punch radius. Different mathematical representations are used to determine the coefficient of friction in the Bending Under Tension Test. In general the change in the strip thickness in passing over the die radius is neglected and the radius of curvature to thickness ratio is assumed to be constant in these equations. However, the effect of roller radius, sheet thickness and the surface pressure are also omitted in some of these equations. This work quantitatively determined the effect of roller radius and the tooling pressure on the coefficient of friction. The Bending Under Tension Test was performed using rollers with different radii and also lubricants with different properties. The tool radii were found to have a direct influence in the contact pressure. The effect of roller radius on friction was considerable and it was observed that there is a clear relationship between the contact pressure and the coefficient of friction.

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High energy consumption remains a key challenge for the widely used ring spinning system. Tackling this challenge requires a full understanding of the various factors that contribute to yarn tension and energy consumption during ring spinning. In this paper, we report our recent experimental and theoretical research on air drag, yarn tension and energy consumption in ring spinning. A specially constructed rig was used to simulate the ring spinning process; and yarn tension at the guide-eye was measured for different yarns under different conditions. The effect of yarn hairiness on the air drag acting on a rotating yarn package and on a ballooning yarn was examined. Models of the power requirements for overcoming the air drag, increasing the kinetic energy of the yarn package (bobbin and wound yarn) and overcoming the yarn wind-on tension were developed. The ratio of energy-consumption to yarn-production over a full yarn package was discussed. A program to simulate yarn winding in ring spinning was implemented, which can generate the balloon shape and predict yarn tension under a given spinning condition. The simulation results were verified with experimental results obtained from spinning cotton and wool yarns.

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Magnesium and its alloys do not in general undergo the same extended range of plasticity as their competitor structural metals. The present work is part I of a study that examines some of the roles deformation twinning might play in the phenomenon. A series of tensile test results are reported for the common wrought alloy AZ31. These data are employed in conjunction with a simple constitutive model to argue that View the MathML source twinning (which gives extension along the c-axis) can increase the uniform elongation in tensile tests. This effect appears to be similar to that seen in Ti, Zr and Cu–Si and in the so called TWIP phenomenon in steel.

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The influence of low-strain deformation behavior on curl and springback in advanced high strength steels (AHSS) was assessed using a bend-under-tension test. The effect of yielding behavior on curl and springback was examined by heat-treating two dual-phase steels to induce yield point elongation, while keeping a relatively constant tensile strength and a constant sheet thickness. A dual-phase and TRIP steel with similar initial thickness and tensile strengths were also examined to investigate the effect of work-hardening on curl and springback. It is shown that while current understanding limits prediction of curl and springback in bending under tension using only the initial sheet thickness and tensile strength, both the yielding and work-hardening behavior can affect the results. Explanations for these effects are proposed in terms of the discontinuous yielding and flow stress in the materials.


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To reveal the mechanism of fibre damage and breakage in the fibre opening processes, the fibre tension during the interaction between a fibre and a pinned beater has been investigated. Details of the interacting force variations and incident of fibre breakage have been closely examined. Many factors which influence the fibre/pin interacting force have been elucidated. The results highlight the causes of fibre damage and breakage by fibre/pin interactions.

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The activation of slip and twinning deformation modes in Mg-3Al-1Zn alloy was investigated by means of both in-situ and ex-situ methods at ambient temperature using electron back scattering diffraction (EBSD). The results confirm the importance of non-basal slip and c-axis compression double twinning. During tensile deformation of rolled sheet, 63% of the observed slip traces were ascribed to prismatic slip, 33% to basal slip and 4% to <c+a> slip. Prismatic slip was frequently observed in grain interiors. The density of twinning was quantified in samples tested along transverse, extrusion and rolling directions at failure. The values in the range of 0.02-0.18 twins per square micron were found depending on sample orientation. The results show the effect of twinning on failure.

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Characteristics of the “contraction” twins, formed close to the fracture surface in Mg–3Al–1Zn alloy deformed in tension approximately perpendicular to the grain c-axes, are investigated using transmission electron microscopy. The grain c-axis contractions were largely accommodated by {1011}-{1012} source double-twins in a variant characterized by 38&deg; ⟨1210⟩ source twin/matrix misorientation in conjunction with dislocation slip. A possible interpretation of the observed preference for this variant formation is given and some crystal plasticity modelling is performed to elucidate the matter.

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Disclosed are emulsions and microcapsules that comprise one or more substances with a low interfacial tension. Methods of making the emulsions and microcapsules as well as methods of using them are also disclosed. In some embodiments microbial oil is used. In some embodiments marine oil is used. In some embodiments the emulsion has a pH of greater than 6,0. In some embodiments the emulsion has a pH of less than 5,0.