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Bai Y.,Beijing Institute of Technology | Wu F.,Beijing Institute of Technology | Yang H.-T.,Tianjin Lishen Battery Joint Stock Co. | Zhong Y.,Patent Examination Cooperation Center | Wu C.,Beijing Institute of Technology
Advanced Materials Research | Year: 2012

Spinel LiMn 2O 4 was modified with Y 2O 3 coating by a chemical process. The crystal structures of the as-prepared samples were investigated by X-ray diffraction (XRD). The charge/discharge characteristics of the modified samples were evaluated at different rates between 3.0 and 4.4V. The discharge capacities of 2.0 wt.% Y 2O 3-coated LiMn 2O 4 are 116 mAh·g -1, 99.7mAh·g -1, 93.3mAh·g -1 and 82.9mAh·g -1 at 0.1C, 0.5C, 1C and 2C rates (at 20°C). The cycle abilities improvement of the spinel LiMn 2O 4 coated with Y 2O 3 are demonstrated at elevated temperature (55°C) and high rates (2C). From the analysis of electrochemical impedance spectroscopy (EIS), the improvement of cycle ability may be attributed to the suppression on the formation of the passivating films and the reduction of Mn dissolution, which result from the surface modification with Y 2O 3. Source

Xu L.,Beihang University | Zhou W.,Beihang University | Li X.,Beihang University | Tang S.,Patent Examination Cooperation Center
IEEE Transactions on Instrumentation and Measurement | Year: 2011

In this paper, a novel approach is presented to the measurement of wet gas flows by using a throat-extended Venturi meter (TEVM) and soft-computing approximation techniques. Results obtained by using an industrial-scale test rig suggest that the flow rate of wet gas flowing in the TEVM is related not only to the static features but also to the dynamic features of the differential pressures (DPs) across the converging and the extended throat sections of the Venturi meter, as well as the static pressure and temperature signals within the Venturi meter. The relation between the signal features and the gas/liquid flow rates of wet gas is established through the use of backpropagation (BP) artificial neural network (ANN) and support vector machine (SVM) approximation techniques. The experimental test carried out within static pressure range of 0.3-0.8 MPa, gas flow rate range of 0.0139-0.0444 m3s/, and liquid flow rate range of 3.0556 × 10-4-0.0015 m3/s suggested that it is a cost-effective and viable method to solve the problem of wet gas metering by combining a revised Venturi meter and soft-computing approximation techniques. © 2006 IEEE. Source

Shao W.,Anhui University of Science and Technology | Shao W.,CAS Beijing National Laboratory for Molecular | Zhang Y.,Anhui University of Science and Technology | Wang Z.,Anhui University of Science and Technology | And 3 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

The influence of the addition of low amounts of ultrahigh-molecular-weight polyethylene (UHMWPE) on the crystallization kinetics of isotactic polypropylene (iPP) in iPP/UHMWPE blends has been investigated by means of differential scanning calorimetry (DSC) and polarized optical microscopy. During the nonisothermal crystallization process, the primarily formed UHMWPE crystals serve as heterogeneous nucleating agents for iPP nucleation, whereas during the isothermal crystallization process, UHMWPE is in the molten state, iPP nucleation preferentially occurs at the UHMWPE and iPP phase interfaces, and the spherulitic growth rates are not obviously affected. It is particularly interesting to find a critical UHMWPE content (2.5 wt %) in the blends to induce the highest iPP nucleation rate; however, above the critical UHMWPE content, the iPP nucleation rate slows because of aggregation of the UHMWPE component. A delicately designed DSC measurement provides insight into the nucleation mechanism of iPP at the interfaces between the UHMWPE and iPP phase domains. It is proposed that the concentration fluctuations generated from the unstable inhomogeneous phase interfaces in the iPP/UHMWPE blends promote the formation of nuclei, which eventually enhances the nucleation and overall crystallization rates of the iPP component. © 2012 American Chemical Society. Source

Li M.,Nankai University | Tian Y.,Nankai University | Tian Y.,Patent Examination Cooperation Center | Zhao Y.,Nankai University | Bu W.,Nankai University
PLoS ONE | Year: 2012

Heteroptera, or true bugs, are the largest, morphologically diverse and economically important group of insects with incomplete metamorphosis. However, the phylogenetic relationships within Heteroptera are still in dispute and most of the previous studies were based on morphological characters or with single gene (partial or whole 18S rDNA). Besides, so far, divergence time estimates for Heteroptera totally rely on the fossil record, while no studies have been performed on molecular divergence rates. Here, for the first time, we used maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) with multiple genes (18S rDNA, 28S rDNA, 16S rDNA and COI) to estimate phylogenetic relationships among the infraorders, and meanwhile, the Penalized Likelihood (r8s) and Bayesian (BEAST) molecular dating methods were employed to estimate divergence time of higher taxa of this suborder. Major results of the present study included: Nepomorpha was placed as the most basal clade in all six trees (MP trees, ML trees and Bayesian trees of nuclear gene data and four-gene combined data, respectively) with full support values. The sister-group relationship of Cimicomorpha and Pentatomomorpha was also strongly supported. Nepomorpha originated in early Triassic and the other six infraorders originated in a very short period of time in middle Triassic. Cimicomorpha and Pentatomomorpha underwent a radiation at family level in Cretaceous, paralleling the proliferation of the flowering plants. Our results indicated that the higher-group radiations within hemimetabolous Heteroptera were simultaneously with those of holometabolous Coleoptera and Diptera which took place in the Triassic. While the aquatic habitat was colonized by Nepomorpha already in the Triassic, the Gerromorpha independently adapted to the semi-aquatic habitat in the Early Jurassic. © 2012 Li et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Chen M.-S.,Central South University | Chen M.-S.,State Key Laboratory of High Performance Complex Manufacturing | Lin Y.C.,Central South University | Lin Y.C.,State Key Laboratory of High Performance Complex Manufacturing | Ma X.-S.,Patent Examination Cooperation Center
Materials Science and Engineering A | Year: 2012

The dynamic recrystallization behavior in 42CrMo steel was investigated by hot compression tests. The effects of deformation temperature, strain rate, and initial austenite grain size on the dynamic recrystallization behavior were discussed. Based on the experimental results, the kinetic equations for the dynamic recrystallization behavior of 42CrMo steel were proposed. Results indicate that the effects of the deformation temperature, strain rate and initial austenitic grain size on the dynamic recrystallization behavior in 42CrMo are significant. The dynamic recrystallization in 42CrMo steel easily occurs at high deformation temperature, low strain rate and fine initial austenitic grain. A good agreement between the experimental and predicted results shows that the proposed kinetic equations can give an accurate estimate of the dynamic recrystallization behavior in hot deformed 42CrMo steel. © 2012 Elsevier B.V. Source

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