Design redundant Chebyshev dictionary with generalized extreme value distribution for sparse approximation and image denoising

This paper illustrates a novel method for designing redundant dictionary from Chebyshev polynomials for sparse coding. Having an overcomplete dictionary in ${{\mathbb R}^{d \times N}:d < N}$ from N, orthogonal functions need to sample d times from orthogonal intervals. It is proved (“Appendix B”) that uniform distribution is not optimal for sampling. Experiments show that using non-uniform measures for dividing orthogonal intervals has some advantages in making incoherent dictionary with a mutual coherence closer to equiangular tight frames, which is appropriate for sparse approximation methods. In this paper, we first describe the dictionary design problem, then modify this design with any kind of distribution, and define an objective function respect to its parameters. Because of the abundant extremums in this objective function, genetic algorithm is used to find the best parameters. Experimental results show that generalized extreme value distribution has better performance among others. This type of dictionary design improves the performance of sparse approximation and image denoising via redundant dictionary. The advantages of this method of designing overcomplete dictionaries are going to be compared with uniform ones in sparse approximation areas.     

Energy absorption behaviour of braided basalt composite tube

Braided composite had been proven to have a great potential as energy absorber. However, the past studies done were limited to synthetic fibre as the reinforcement composite. In this study, we focused on a natural fibre, namely basalt, as the reinforcement material. The effects of braid thickness, braid angle and braid tow density of the basalt composite tube subjected to quasi-static crushing response were investigated. Crushing failure mode had been observed in comparing those braid parametric effects. Moreover, the analysis of variance was used to analyse the main and interaction effects subjected to specific energy absorption (SEA) response for the test. Three crushing modes had been observed. The splayed and diamond shape of progressive folding were reported for the braid angles of ±30° and ±45°, respectively, and fibre micro-cracking mode effects for the ±60° braid angle. Furthermore, SEA increased with the decrease of braid angle and increase of diameter-to-thickness ratio. On the other hand, the highest braid angle demonstrated the lowest crush efficiency and poor triggering crushing progression.     

Non-hydrolytic sol–gel route to a family of hybrid mesoporous aluminosilicate ethanol dehydration catalysts

Journal of Materials Science - Hybrid materials are intensely studied for potential applications in heterogeneous catalysis. Organic groups at the catalyst surface can modify not only its...     

Phenyl-thio-carbamide perception by adult Tribolium castaneum

Chemoperception was studied in Tribolium castaneum. The ability of the adults to distinguish between normal medium (95% whole wheat flour and 5% dried yeast) and normal medium supplemented with 4% phenyl-thio-carbamide (PTC) was tested in a Y-shaped maze made of glass. Males and females were observed separately. Both sexes preferred normal medium; however, more females (40%) chose the PTC medium than did males (21%).

The PTC chemoreceptor was found to be localized in the antennae, which when removed caused both sexes to lose their ability to discriminate between the two media. Female beetles required both antennae to sense PTC. On the other hand, one antenna compensated for the loss of the other in males in avoiding this compound, even though the operation reduced the activity of the antennectomized beetles. Antennectomy resulted in doubling the number of unresponsive beetles that stayed at the source for both sexes (males were less responsive than females). The loss of the right or the left antenna made no difference in the unresponsiveness or the choice between the two media.     

Mimosa tannin resins for impregnated paper overlays

The surface quality of plywood coated with resin impregnated papers based on tannin/furfuryl alcohol resins was studied. Several hardeners such as hexamine, paraformaldehyde, formurea and a mixture of formurea and paraformaldehyde were added in small quantities to a mimosa tannin/furfuryl alcohol resin. Papers impregnated with resin based on tannin + furfuryl alcohol + paraformaldehyde, or + formurea were found to yield excellent results in standard water vapour resistance and cross-cut tests. Matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry and cross-polarisation-magic angle spinning NMR (CP-MAS ¹³C NMR) were used to show coreaction of tannin with furfuryl alcohol and even furfuryl alcohol self condensation under alkaline conditions, as well as coreaction of formaldehyde-yielding compounds such as hexamine with both tannin aromatic rings and the aromatic ring of furfuryl alcohol. Some of the more important oligomers formed were identified by MALDI-TOF.     

Metamodels in Europe: Languages, Tools, and Applications

Editor's note:This article provides an overview of current efforts in Europe for using metamodeling in the integrated development of critical systems such as automotive electronics. It distinguishes between lightweight versus heavyweight approaches, surveys a number of related current European projects, and gives details about the Speeds project to illustrate the role of metamodeling-driven system engineering.—Sandeep Shukla, Virginia Tech