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61.
Stuart C. Wimbush Dominic Walsh Simon R. Hall 《Physica C: Superconductivity and its Applications》2010,470(7-8):373-377
We have recently demonstrated that through a sol–gel route, superconductor crystallization in the presence of simple biopolymers results in a drastic alteration of morphology, producing technologically useful nanowires and porous architectures. Morphological control is of the utmost importance to bulk high-temperature superconductors, as grain boundaries act as weak links in limiting the achievable critical current density (Jc). Here we show that, as expected, the incorporation of nanoparticulate barium zirconate (BaZrO3) species into a biopolymer-mediated synthetic protocol for YBa2Cu3O7?δ (Y123) leads to a significantly improved in-field Jc compared to that observed in a sample without BaZrO3 additions. To ameliorate degradation of the BaZrO3 species in this protocol, we demonstrate that by drawing the precursor sol into fibers, a microtape architecture is able to be formed, leading to lengthy, anisotropic structures having enhanced Jc through the retention of the BaZrO3 species. 相似文献
62.
Bone provides an important source of forensic evidence. The storage conditions of bone have been recognised as a factor in
maintaining the integrity of such evidence. Thermogravimetric analysis (TG) has been employed to examine the effects of storage
environments and preparation methods on the structural properties of pig bones. A comparison of oven and freeze drying has
been made to study the effect of storage conditions. A comparison has also been made of ground bone specimens with cut specimens.
Freeze-dried hand ground specimens provided the most consistent results and, thus, this is the recommended method of preparation
of bone specimens for TG analysis. 相似文献
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David J. Lowe Andrew V. Chapman Stuart Cook James J. C. Busfield 《Journal of Polymer Science.Polymer Physics》2011,49(22):1621-1627
Small strain Young's moduli of natural rubber (NR)/organoclay nanocomposites were estimated using the Guth–Gold, Halpin–Tsai (HT), and Krieger–Dougherty (KD) models, and compared with experimental measurements of NR vulcanizates containing organo‐montmorillonite (OM) or organo‐sepiolite (OS). To account for the effect on modulus of the NR matrix of the vulcanization‐active modifier in the organoclay, a matrix modulus correction (MMC) term was derived from the vulcanization parameters of the nanocomposites. The KD model gave a better empirical fit with the experimental data than the Guth–Gold model, with both giving good agreement with particle shape factors estimated from transmission electron microscope (TEM) images. The HT model gave the best fit with experiment for both types of nanocomposite, and use of the MMC term meant that the empirical shape factor was sufficiently close to that estimated from TEM images that the model could potentially be used to accurately predict the Young's moduli of NR/OM and NR/OS nanocomposites. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1621–1627, 2011 相似文献
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C. A. Stuart 《Milan Journal of Mathematics》2011,79(1):327-341
For a class of second order quasilinear elliptic equations we establish the existence of two non–negative weak solutions of
the Dirichlet problem on a bounded domain, Ω. Solutions of the boundary value problem are critical points of C
1–functional on H01(W){H_0^1(\Omega)}. One solution is a local minimum and the other is of mountain pass type. 相似文献
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69.
This paper proposes a problem decomposition approach to solve hard Frequency Assignment Problem instances with standard meta-heuristics.
The proposed technique aims to divide the initial problem into a number of easier subproblems, solve them and then recompose
the partial solutions into one of the original problem. We consider the COST-259 MI-FAP instances and other Cardiff University
test problems in order to simulate larger and more realistic networks. For both benchmarks the standard implementations of
meta-heuristics do not generally produce a satisfactory performance within reasonable times of execution. However, the decomposed
assignment approach can improve their results, both in terms of solution quality and runtime. 相似文献
70.