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Xi'an, China

Feng H.-J.,Changan University
Journal of Magnetism and Magnetic Materials | Year: 2012

Ab initio calculations show that the coupling between antiferrodistortive (AFD) distortions and magnetization in perovskite Bi 2FeMnO 6 is prohibited to make magnetization rotate as effective Hubbard parameter is larger than 2.7 eV, where anomalies in antiferromagnetic (AFM) vectors and band gap varying with on-site Coulomb interaction can be observed. This coupling is attributed to the antisymmetric DzyaloshinskiiMoriya interaction driven by the e ge g states AFM interaction and charge redistribution with respect to different AFD distortions. © 2011 Elsevier B.V. All rights reserved. Source

Yang X.,Changan University
IET Signal Processing | Year: 2012

A new method for the dual estimation in dynamic state-space model was proposed in this study with a focus on sequential Bayesian learning about time-varying state and static parameter simultaneously. The proposed algorithm combines auxiliary particle filtering (APF) with particle swarm optimisation (PSO) to achieve computational efficiency and stability. The PSO provides the mechanism for generating new parameter values for the particle filtering at each time step. By properly choosing the fitness function of PSO, the algorithm produces the recursive maximum-likelihood estimation of the parameter. It is shown that PSO can be integrated with APF in the simulation-based sequential frame for dual estimation. The algorithm is tested on Markov switching stochastic volatility model with promising results compared with existing ones. © 2012 The Institution of Engineering and Technology. Source

Shen P.,CAS Institute of Geology and Geophysics | Pan H.,Changan University
Lithos | Year: 2013

The Baogutu porphyry Cu deposit, located in the West Junggar Region, Xinjiang, China, has the reduced mineralization features. Baogutu is associated with a Late Carboniferous intrusive complex that was emplaced into Lower Carboniferous volcano-sedimentary sequences. The complex consists of a main-stage diorite stock and late-stage diorite porphyry dikes. The former hosts the most of the Cu mineralization. The main-stage stock has a wide range of composition, from minor gabbro through dominant diorite to tonalite porphyry. These are all inhomogeneous over a few meters, with no distinct boundary between the gabbro, diorite and tonalite porphyry. Some felsic microgranular enclaves and heterogeneous phenocrysts occur in these rocks: the latter is a single mineral with a range of compositions. The elemental and Sr-Nd compositions of the tonalite porphyry have a transitional character from the gabbro and diorite to the country rocks. These findings suggest possible country-rock contamination. Mineral composition data suggest that the primary magma at Baogutu is oxidized I-type magma. The gabbro and diorite have high positive εNd(t) (+3.3 to +6.0) and low initial 87Sr/87Sr ratios (0.7035-0.7038), and are characterized by moderately fractionated rare earth element (REE) patterns, pronounced Nb depletion and weak negative Eu anomalies. These observations suggest that the Baogutu magmas were derived from partial melting of a metasomatized mantle wedge and underwent significant country-rock contamination after emplacement. The contamination process involved the felsic components and reduced materials (e.g. Carbonaceous sediment), which caused the chemical variation of the Baogutu rocks and the reduced mineralization features in the Baogutu deposit. Thus, contamination played an important role in the formation of the host rocks and associated mineralization at Baogutu. © 2013 Elsevier B.V. Source

Li W.,Changan University
Advances in Information Sciences and Service Sciences | Year: 2012

In this paper, we investigate the multiple attribute decision making (MADM) problems for evaluating the software quality with interval intuitionistic trapezoidal fuzzy information. We utilize the interval intuitionistic trapezoidal fuzzy weighted geometric(IITFWG) operator to aggregate the interval intuitionistic trapezoidal fuzzy information corresponding to each alternative and get the overall value of the software systems, then rank the software systems and select the most desirable one(s) by using the formula of the score function and accuracy function. Finally, an illustrative example for evaluating the software quality is given to verify the developed approach and to demonstrate its practicality and effectiveness. Source

Zhang W.X.,Changan University | He C.,Xian Jiaotong University
Journal of Physical Chemistry C | Year: 2010

The melting behaviors and transport properties of Cu nanowires (NWs) are studied for the future application as interconnects in microelectronics by using first-principles molecular dynamics (FP-MD) and classical molecular dynamics (MD) methods. The results of the potential energy, Cp(T), the quantum conduction, and the density of states are used to monitor the phase transition. It is found that the melting temperature using the MD method is 10% higher than that using the FP-MD method, and the corresponding FP-MD results of Cu NWs are predicted with the diameter of 2-6 nm. Meanwhile, the size effects of the nanowires on the melting temperature are validated by the theoretical model. © 2010 American Chemical Society. Source

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