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The structural, elastic, anisotropic, and thermodynamic properties of P3m1-BC7 and Pmm2-BC7 have been studied in this paper utilizing first-principles calculations. In comparison with the elastic properties of Pmm2-BC7, P3m1-BC7 exhibits slightly higher values in bulk modulus and B/G, with similar values in shear modulus, the Young modulus, and the Poisson ratio. The calculated Pugh modulus ratio (B/G) and the Poisson ratio demonstrates P3m1-BC7 from brittle to ductile at 93.60 and 93.73 GPa, respectively. Calculations of shear anisotropic factor, universal elastic anisotropy index, shear modulus, the Young modulus, and the Poisson ratio for BC7 then demonstrate that Pmm2-BC7 exhibits a larger elastic anisotropy than P3m1-BC7. Quasi-harmonic Debye model is finally applied to investigate the Debye temperature, the coefficient of thermal expansion, heat capacity and Grüneisen parameter of Pmm2-BC7 and P3m1-BC7. [ABSTRACT FROM AUTHOR]

Nowadays, we are living in an information overload age. A tremendous amount of information has been produced on the Internet, how to find the interesting information is the main goal of recommendation system research. However, the most of current traditional recommendation algorithms (such as Collaborative filtering) are suffering from flowing difficulties: (i) The traditional recommendation system assume that users are independent and identically distributed; this assumption fails to consider the social relation and connection between users, which is not consistent with the social relations in our real world. (ii) Although there are some recommendation system research began to focus on the trust relationship between users, trust information is also very sparse. This leads to most of datasets only contains very little information about the user's relationship. In this paper, we propose an innovative method that integrated users' trust propagation and singular value decomposition into recommendation Algorithm to improve the quality of the recommendation effectively and efficiently. We performed our experiments on two real data sets respectively, the public domain Epinions.com and Filemtrust.com. The experimental results show that our method has a better outperform. [ABSTRACT FROM AUTHOR]

I4-carbon was first proposed by Zhang et al., this paper will report regarding this phase of carbon. The present paper reports the structural and elastic properties of the three-dimensional carbon allotrope I4-carbon using first-principles density functional theory. The related enthalpy, elastic constants, and phonon spectra confirm that the newly-predicted I4-carbon is thermodynamically, mechanically, and dynamically stable. The calculated mechanical properties indicate that I4-carbon has a larger bulk modulus (393 GPa), shear modulus (421 GPa), Young's modulus (931 GPa), and hardness (55.5 GPa), all of which are all slightly larger than those of c-BN. The present results indicate that I4-carbon is a superhard material and an indirect-band-gap semiconductor. Moreover, I4-carbon shows a smaller elastic anisotropy in its linear bulk modulus, shear anisotropic factors, universal anisotropic index, and Young's modulus. [ABSTRACT FROM AUTHOR]

An efficient multifocus image fusion scheme in nonsubsampled contourlet transform (NSCT) domain is proposed. Based on the property of optical imaging and the theory of defocused image, we present a selection principle for lowpass frequency coefficients and also investigate the connection between a low-frequency image and the defocused image. Generally, the NSCT algorithm decomposes detail image information indwells in different scales and different directions in the bandpass subband coefficient. In order to correctly pick out the prefused bandpass directional coefficients, we introduce multiscale curvature, which not only inherits the advantages of windows with different sizes, but also correctly recognizes the focused pixels from source images, and then develop a new fusion scheme of the bandpass subband coefficients. The fused image can be obtained by inverse NSCT with the different fused coefficients. Several multifocus image fusion methods are compared with the proposed scheme. The experimental results clearly indicate the validity and superiority of the proposed scheme in terms of both the visual qualities and the quantitative evaluation. [ABSTRACT FROM AUTHOR]