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941.
Ying Wai Fan 《Linear algebra and its applications》2011,434(11):2244-163
In this paper we introduce a new boundary condition that can be used when reconstructing an image from observed blurred and noisy data. Our approach uses information from the observed image to enforce boundary conditions that continue image features such as edges and texture across the boundary. Because of its similarity to methods used in texture synthesis, we call our approach synthetic boundary conditions. We provide an efficient algorithm for implementing the new boundary condition, and provide a linear algebraic framework for the approach that puts it in the context of more classical and well known image boundary conditions, including zero, periodic, reflective, and anti-reflective. Extensive numerical experiments show that our new synthetic boundary conditions provide a more accurate approximation of the true image scene outside the image boundary, and thus allow for better reconstructions of the unknown, true image scene. 相似文献
942.
Shu‐Hua Zhang Dr. Hong‐Wei Xi Prof. Dr. Kok Hwa Lim Qingyong Meng Prof. Dr. Ming‐Bao Huang Prof. Dr. Cheuk‐Wai So 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4258-4263
The synthesis and characterization of a singlet delocalized 2,4‐diimino‐1,3‐disilacyclobutanediyl, [LSi(μ‐CNAr)2SiL] ( 2 , L: PhC(NtBu)2, Ar: 2,6‐iPr2C6H3), and a silylenylsilaimine, [LSi(?NAr)? SiL] ( 3 ), are described. The reaction of three equivalents of the disilylene [LSi? SiL] ( 1 ) with two equivalents of ArN?C?NAr in toluene at room temperature for 12 h afforded [LSi(μ‐CNAr)2SiL] ( 2 ) and [LSi(?NAr)? SiL] ( 3 ) in a ratio of 1:2. Compounds 2 and 3 have been characterized by NMR spectroscopy and X‐ray crystallography. Compound 2 was also investigated by theoretical studies. The results show that compound 2 possesses singlet biradicaloid character with an extensive electronic delocalization throughout the Si2C2 four‐membered ring and exocyclic C?N bonds. Compound 3 is the first example of a silylenylsilaimine, which contains a low‐valent silicon center and a silaimine substituent. A mechanism for the formation of 2 and 3 is also proposed. 相似文献
943.
A rigorous statistical method is established to compute the rate constants of the bimolecular decomposition of redox catalysts used to initiate polymer chains. Results obtained for the systems styrene-dimethylaniline-benzoyl peroxide and acrylamide-thio-glycollic acid-potassium bromate compare favorably with those reported by other workers. The merits of this error-in-variable technique, which outperforms conventional nonlinear least-square analysis and the dead-end polymerization method, are discussed. 相似文献
944.
Mohammed Harun Chakrabarti Nigel P. Brandon Farouq S. Mjalli Laleh Bahadori Inas M. Al Nashef Mohd. Ali Hashim M. A. Hussain Chee Tong John Low Vladimir Yufit 《Journal of solution chemistry》2013,42(12):2329-2341
Seven commercially sourced acetylacetonate salts were investigated in deep eutectic solvents (DESs that were prepared from ethylene glycol and trifluoroacetamide hydrogen bond donors) by cyclic voltammetry, to identify electrolytes suitable for future applications in electrochemical energy storage devices. Although the solubilities are low and on the order of 0.02 mol·L?1 for the most soluble salts, some were found to display encouraging quasi-reversible electrochemical kinetics. For instance, the diffusion coefficients of copper(II) acetylacetonate and iron(III) acetylacetonate in the trifluoroacetamide based DES are 1.14 × 10?8 and 5.12 × 10?9 cm2·s?1, which yields rate constants of 3.16 × 10?3 and 8.43 × 10?6 cm·s?1, respectively. These results are better than those obtained with the DESs prepared from ethylene glycol. The poor kinetics of the iron(III) acetylacetonate system was possibly due to the hygroscopic nature of the DESs that resulted in a continuous build-up of moisture in the system in spite of the maintenance of an inert atmosphere by means of a plastic glove bag. Further work is thus envisaged in an inert dry box that could lead to H-type glass cell charge/discharge experiments in the future. 相似文献
945.
In [10], the authors have designed a new fifth order WENO finite-difference scheme by adding a higher order smoothness indicator which is obtained as a simple and inexpensive linear combination of the already existing low order smoothness indicators. Moreover, this new scheme, dubbed as WENO-Z, has a CPU cost which is equivalent to the one of the classical WENO-JS [2], and smaller than that of the mapped WENO-M, [5], since it involves no mapping of the nonlinear weights. In this article, we take a closer look at Taylor expansions of the Lagrangian polynomials of the WENO substencils and the related inherited symmetries of the classical lower order smoothness indicators to obtain a general formula for the higher order smoothness indicators that allows the extension of the WENO-Z scheme to all (odd) orders of accuracy. We further investigate the improved accuracy of the WENO-Z schemes at critical points of smooth solutions as well as their distinct numerical features as a result of the new sets of nonlinear weights and we show that regarding the numerical dissipation WENO-Z occupies an intermediary position between WENO-JS and WENO-M. Some standard numerical experiments such as the one dimensional Riemann initial values problems for the Euler equations and the Mach 3 shock density-wave interaction and the two dimensional double-Mach shock reflection problems are presented. 相似文献
946.
The effect of UV radiation on both pure and additive-containing polyaniline thin films is described. Experimental investigations
included optical transmittance spectroscopy and electrical conductivity measurements. Exposure to UV radiation in the range
of 380 to 400 nm was seen to increase film transmittance by 4% through photobleaching. Different gas ambients were employed
for this experiment and progressively more photobleaching was observed for nitrogen, air and oxygen atmospheres. This effect
arises due to the destruction of quinoid and benzenoid chromophores on the polymer backbone. Concomitantly, a decrease in
film resistivity was also observed and this can be attributed to increased oxidative doping of the film material. The addition
of controlled amounts of Tinuvin 213—an ultraviolet absorber (UVA) material—was seen to reduce the UV-induced degradation
of polyaniline thin films by absorption of UV photons through regenerative intramolecular photolysis. 相似文献
947.
Chee Heng Teo 《Journal of Physics and Chemistry of Solids》2011,72(7):886-890
This paper reports on investigations carried out to study the behaviour of contacts between polyaniline and surface electron-rich solids. The objective of the study was to study polymer-conducting system hybrids. Experiments were carried out on three metals, graphite sheets and on indium arsenide. The results show that in the case of metals, where there is good alignment of the metal's Fermi level with the LUMO bands of the polymer one gets a lower contact resistance. With graphite a good, low resistance, ohmic contact was obtained whereas with indium arsenide a non-linear I-V characteristic was observed. Behaviour of a polyaniline-silica-silicon structure is also described where gate-controlled conductivity enhancement was observed. 相似文献
948.
949.