Tianjin, China

Tianjin Normal University

Tianjin, China

Tianjin Normal University is a university in Tianjin, China. Wikipedia.

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Huang C.,Tianjin Normal University
Annals of Physics | Year: 2017

The existence and stability of fundamental, dipole and tripole solitons are investigated in parity-time symmetric potential with competing gain and loss. The competing parameter decides both the width of potential and loss or gain region. All these solitons exist in the potential with a suitable width. It is easy to form a fundamental soliton when increasing the parameter k. To form a dipole and a tripole soliton, the values of k should locate in some region. The multimode solitons are unstable for a larger power while may be stable for a relatively small one. The effects of competing gain or loss profile on the stability of these solitons are investigated with a linear stability analysis corroborated by a beam propagation method. © 2017 Elsevier Inc.

Zhang X.,Tianjin Normal University
Pattern Recognition | Year: 2017

Multimodal data commonly exists in human lives. Early analysis usually concentrates on mining information based on single modality. Recent studies show that learning tasks could be greatly enhanced by analyzing data from the aspect of multimodality. This paper deals with classifying multimodal data comprised of visual and acoustic contents. Different data features are fused under a hierarchical structure to achieve a good semantic understanding. Then, to accomplish accurate classification, an adaptive support vector machine method (ASVM) is proposed. The method is support vector machine with hyperparameters controlled by a novel and efficient artificial bee colony algorithm. First, a micro colony is set as the number of hyperparameters is usually less than 5. Second, one position inheritance based on roulette wheel selection is used. Third, discarded solutions are mutated by position shift operation instead of random reinitialization. The ASVM method is first verified on classical data sets demonstrating the goodness of the proposed method. Then the proposed method is applied on a multimodal data set. Each sample includes both image and audio data features. Experimental results show that the ASVM method is more effective and robust than the compared methods. © 2017 Elsevier Ltd.

Zhou L.,Tianjin Normal University
Nonlinear Dynamics | Year: 2013

In this paper, the problem of dissipativity is investigated for cellular neural networks with proportional delays. Without assuming monotonicity, differentiability, and boundedness of activation functions, two new delay-independent criteria for checking the dissipativity of the addressed neural networks are established by using inner product properties and matrix theory. Two examples and their simulation results are given to show the effectiveness and less conservatism of the proposed criteria. © 2013 Springer Science+Business Media Dordrecht.

Zhou L.,Tianjin Normal University
Nonlinear Dynamics | Year: 2014

Proportional delay, which is different from distributed delay, is a kind of unbounded delay. The proportional delay system as an important mathematical model often rises in some fields such as physics, biology systems, and control theory. In this paper, the uniqueness and the global asymptotic stability of equilibrium point of cellular neural networks with proportional delays are analyzed. By using matrix theory and constructing suitable Lyapunov functional, delay-dependent and delay-independent sufficient conditions are obtained for the global asymptotic stability of cellular neural networks with proportional delays. These results extend previous works on these issues for the delayed cellular neural networks. Two numerical examples and their simulation are given to illustrate the effectiveness of obtained results. © 2014 Springer Science+Business Media Dordrecht.

Feng Y.,Tianjin Normal University
Electrochimica Acta | Year: 2010

Silicon.carbon.nitrogen material (SiCN) is pyrolyzed from polysilylethylenediamine (PSEDA) derivation, followed by a heat-treating process at 1000°C in Ar atmosphere. This heat-treated SiCN material has an excellent electrochemical performance as an anode for lithium ion batteries. Charge.discharge cycle measurements show that the heat-treated SiCN material exhibits a high first cycle discharge capacity of 829.0mAhg-1 and stays between 400 and 370mAhg-1 after 30 cycles. The discharge capacity remains above 300mAhg-1 at the high current density of 80 and 160mAg-1. These values are higher than untreated SiCN and commercial graphite anodes, which indicates that the heat-treating process improves the charge.discharge capacity, cycle stability and high-rate ability of SiCN anode. It is seemed that changes of SiCN structure, the formation of loose nano-holes on material surface and the formation of graphitic carbon phase in heat-treating process contribute to the improvement of electrochemical properties for SiCN anode. © 2010 Elsevier Ltd. All rights reserved.

Li C.-P.,Tianjin Normal University | Du M.,Tianjin Normal University
Chemical Communications | Year: 2011

Solvent effect is a vital subject in the domain of coordination chemistry. In this connection, previous researches mainly focus on the role of solvents in reaction kinetics and thermodynamics during the coordination processes. In virtue of the recent efforts on coordination supramolecular systems, especially coordination polymers or metal-organic frameworks, this feature article aims to demonstrate the solvent effect on regulating such diversiform metallosupramolecular solids, incorporating their crystal growth/assembly, structural modulation, dynamic transformations, and potential applications, which may provide new insights into the rational design and construction of such advanced crystalline materials. © 2011 The Royal Society of Chemistry.

Zhao X.,Tianjin Normal University | Zhang Y.,CAS Beijing National Laboratory for Molecular | Wang J.,CAS Beijing National Laboratory for Molecular
Chemical Communications | Year: 2012

Copper-catalyzed reaction of diazo compounds generates copper carbene intermediates that undergo diverse transformations. In recent years, the selectivity and efficiency of these important conversions have been further improved. In particular, breakthroughs have been made in catalytic asymmetric polar X-H bond insertion reactions. Moreover, novel transformations based on copper carbene, namely copper-catalyzed cross-couplings of diazo compounds, have emerged as powerful methods for carbon-carbon bond formations. This feature article summarizes the most recent developments in this area. © The Royal Society of Chemistry 2012.

Zhou L.,Tianjin Normal University
Neural Processing Letters | Year: 2013

Global exponential stability of a class of cellular neural networks with multi-proportional delays is investigated. New delay-dependent sufficient conditions ensuring global exponential stability for the system presented here are related to the size of the proportional delay factor, by employing matrix theory and Lyapunov functional, and without assuming the differentiability, boundedness and monotonicity of the activation functions. Two examples and their simulation results are given to illustrate the effectiveness of the obtained results. © 2012 Springer Science+Business Media New York.

Du M.,Tianjin Normal University | Li C.-P.,Tianjin Normal University | Liu C.-S.,Zhengzhou University of Light Industry | Fang S.-M.,Zhengzhou University of Light Industry
Coordination Chemistry Reviews | Year: 2013

The rational construction of coordination polymers (CPs), normally existing as infinite crystalline lattices extended from inorganic vertices and organic struts, essentially benefits from the development of crystal engineering strategies. In this review, we summarily comment on the key advances in the design of CPs using mixed-ligand synthetic strategy and discuss the relationship between the specifically selected mixed organic ligands and the resulting CPs. Significantly, fine tuning on the structural features of organic ligands, such as spacers, positional isomers, and substituents, can lead to a delicate regulation of the diverse network structures of CPs. Additionally, such mixed-ligand coordination assemblies may also be heavily affected by metal ion, synthetic route, and some other external stimuli such as solvent and pH condition, etc. The advantages of mixed-ligand systems as promising approaches to construct CPs-based crystalline materials with interesting structures and useful properties will also be demonstrated. © 2012 Elsevier B.V.

LiFePO4-MWCNTs (multi-walled carbon nanotubes) composite cathode materials were prepared by mixing LiFePO4 and MWCNTs in ethanol followed by heat-treatment at 500 °C for 5 h. The structural, morphology and electrochemical performances of LiFePO4-MWCNTs composite materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge cycle tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that MWCNTs adding improved the electronic conductivity, the discharge capacity, cycle stability and lithium ion diffusion kinetics of LiFePO4, but MWCNTs adding did not charge the orthorhombic olivine-type structure of LiFePO4. In all these prepared LiFePO4 with x wt.% MWCNTs (x = 4, 7, 10) composites, 7 wt.% MWCNTs adding composite cathode shows the best electrochemical performance, which gets an initial discharge capacity of 152.7 mAh g-1 at 0.18 C discharge rates with capacity retention ratio of 97.77% after 100 cycles. © 2010 Elsevier B.V. All rights reserved.

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