22,906 research outputs found

    Sarah Turner - eco-artist and designer through craft-based upcycling

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    Sarah Turner is an eco-artist and designer who practices craft-based upcycling with waste plastic bottles and cans to create lighting, sculpture and decorative home interior products. Since 1998, her enthusiasm, creativity and good will have allowed her to gain several high-profile client commissions and to win awards from design, innovation and business competitions. The aim of this portrait is to introduce Sarah’s work and shed light on the resources, knowledge and skills involved in her practice and on the barriers to and drivers for her craft-based upcycling. We consider that Sarah’s work could be one of the stepping stones for a shift towards more sustainable craft practice, both in the United Kingdom and beyond. By exploring the right ingredients for craft-based upcycling, barriers liable to be faced and key drivers that stimulate motivation, we hope that this portrait will inspire and attract more designers and makers to embed upcycling in their future practice

    Polymer Release out of a Spherical Vesicle through a Pore

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    Translocation of a polymer out of curved surface or membrane is studied via mean first passage time approach. Membrane curvature gives rise to a constraint on polymer conformation, which effectively drives the polymer to the outside of membrane where the available volume of polymer conformational fluctuation is larger. Considering a polymer release out of spherical vesicle, polymer translocation time τ\tau is changed to the scaling behavior τ∌L2\tau\sim L^2 for R<RGR<R_G, from τ∌L3\tau\sim L^3 for R≫RGR\gg R_G, where LL is the polymer contour length and RR, RGR_G are vesicle radius and polymer radius of gyration respectively. Also the polymer capture into a spherical budd is studied and possible apparatus for easy capture is suggested.Comment: 14 pages RevTeX, 6 postscript figures, published in Phys. Rev. E 57, 730 (1998

    On equivalence of discrete-discrete and continuum-discrete design sensitivity analysis

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    Developments in design sensitivity analysis (DSA) method have been made using two fundamentally different approaches as shown. In the first approach, a discretized structural finite element model is used to carry out DSA. There are three different methods in the discrete DSA approach: finite difference, semi-analytical, and analytical methods. The finite difference method is a popular one due to its simplicity, but a serious shortcoming of the method is the uncertainty in the choice of a perturbation step size of design variables. In the semi-analytical method, the derivatives of stiffness matrix is computed by finite differences, whereas in the analytical method, the derivatives are obtained analytically. For the shape design variable, computation of analytical derivative of stiffness matrix is quite costly. Because of this, the semi-analytical method is a popular choice in discrete shape DSA approach. However, recently, Barthelemy and Haftka presented that the semi-analytical method can have serious accuracy problems for shape design variables in structures modeled by beam, plate, truss, frame, and solid elements. They found that accuracy problems occur even for a simple cantilever beam. In the second approach, a continuum model of the structure is used to carry out DSA

    Mode-medium instability and its correction with a Gaussian reflectivity mirror

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    A high power CO2 laser beam is known to deteriorate after a few microseconds due to a mode-medium instability (MMI) which results from an intensity dependent heating rate related to the vibrational-to-translational decay of the upper and lower CO2 lasing levels. An iterative numerical technique is developed to model the time evolution of the beam as it is affected by the MMI. The technique is used to study the MMI in an unstable CO2 resonator with a hard-edge output mirror for different parameters like the Fresnel number and the gas density. The results show that the mode of the hard edge unstable resonator deteriorates because of the diffraction ripples in the mode. A Gaussian-reflectivity mirror was used to correct the MMI. This mirror produces a smoother intensity profile which significantly reduces the effects of the MMI. Quantitative results on peak density variation and beam quality are presented
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