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Singular perturbation for the weakly nonlinear reaction diffusion equation with boundary perturbation

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Applied Mathematics and Mechanics(English Edition) 2008年第8期29卷 1105-1110页

作者： MO jia-qi Department of Mathematics Anhui Normal University Wuhu 241000 Anhui Province P. R. China Department of Mathematics Huzhou Teachers College Huzhou 313000 Zhejiang Province P. R. China Division of Computational Science E-Institutes of Shanghai Universities at Shanghai Jiaotong University Shanghai 200240 P. R. China

In this paper, a class of nonlinear singularly perturbed initial boundary value problems for reaction diffusion equations with boundary perturbation are considered under suitable conditions. Firstly, by dint of the regular perturbation method, the outer solution of the original problem is obtained. Secondly, by using the stretched variable and the expansion theory of power series the initial layer of the solution is constructed. And then, by using the theory of differential inequalities, the asymptotic behavior of the solution for the initial boundary value problems is studied. Finally, using some relational inequalities the existence and uniqueness of solution for the original problem and the uniformly valid asymptotic estimation are discussed.

关键词： nonlinear reaction diffusion singular perturbation boundary perturbation

Solution of Travelling Wave for Nonlinear Disturbed Long-Wave System

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Communications in Theoretical Physics 2011年第3期55卷 387-390页

作者： MO jia-qi Department of Mathematics Anhui Normal University Wuhu 241003 China Division of Computational Science E-Institutes of Shanghai Universities at SJTU Shanghai 200240 China

The approximate expressions of the travelling wave solutions for a class of nonlinear disturbed long-wave system are constructed using the generalized variational iteration method.

关键词： nonlinear long-wave equation travelling wave approximate analytic solution

A Bifurcated Vascular Channel Construction Method based on Diploic Vein Characteristics

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Journal of Bionic Engineering 2019年第5期16卷 814-827页

作者： jian qi jia Li Shuxian Zheng Tianjin Key Laboratory of Equipment Design and Manufacturing Technology School of Mechanical EngineeringTianjin UniversityTianjin 300354China School ofMechanical Engineering Tianjin University of Technology and EducationTianjin 300222China

In skull bone tissue engineering,cells do not easily survive and proliferate in the scaffold because of the lack of nutrient transport *** address these problems,a vascular design and fabrication method based on human skull diploic vein characteristics was *** skull sample was scanned by micro-CT,and the 3D model was constructed by *** analyzing the characteristics of the diploic vein,the vascular centerline model,path model,taper model and bifurcation model were *** vascular network examples were constructed by iteration of the bifurcation *** mold method of constructing vascular scaffolds embedded within the bionic channels was *** scaffold material is PDMS,and the surface was coated with *** Human Umbilical Vein Endothelial Cells(HUVECs)were planted into the lumen of the channels for 7 days in vitro and found to be able to *** cells cultured for three days were fluorescently stained,and it was found that the cells were well attached to the surfaces of the *** vascular design and fabrication process can lay a foundation for vascularization in bone tissue engineering.

关键词： diploic vein vascular channels bifurcation model vascular mold vascular scaffold fabrication bionic

Progress on multiphase layered transition metal oxide cathodes of sodium ion batteries

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Chinese Chemical Letters 2020年第9期31卷 2167-2176页

作者： qi Wang Shiyong chu Shaohua Guo Center of Energy Storage Materials&Technology College of Engineering and Applied SciencesJiangsu Key Laboratory of Artificial Functional MaterialsNational Laboratory of Solid State Microstructuresand Collaborative Innovation Center of Advanced MicrostructureNanjing UniversityNanjing 210093China

As one of the most promising secondary batteries in large-scale energy storage,sodium ion batteries(SIBs) have attracted wide attention due to the abundant raw materials and low *** transition metal oxides are one kind of popular cathode material candidates because of its easy synthesis and large theoretical specific ***,the most common P2 and O3 phases show distinct structural characteristics respectively.O3 phase can serve as a sodium reservoir,but it usually suffers from serious phase transition and sluggish *** the P2 phase,it allows the fast sodium ion migration in the bulk and the structure can maintain stable,but it is lack of sodium,showing a great negative effect on Coulombic efficiency in full ***,single phase structure almost cannot achieve satisfied comprehensive sodium storage *** these circumstances,exploiting novel multiphase cathodes showing synergetic effect may give solution to these *** this review,we summarize the recent development of multiphase layered transition metal oxide cathodes of SIBs,analyze the mechanism and prospect the future potential research directions.

关键词： Sodium ion batteries Cathodes Layered transition metal oxides Biphase materials Triphase materials

Enhanced ferromagnetism and magnetoelectric response in quenched BiFeO3-based ceramics

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Chinese Physics B 2020年第8期29卷 465-470页

作者： qi Pan Bao-Jin chu Key Laboratory of Materials for Energy Conversion Chinese Academy of Sciences(CAS)Department of Materials Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

The piezoelectric,ferromagnetism,and magnetoelectric response of BiFeO3-BaTiO3 ceramics with the compositions around the morphotropic phase boundary(MPB)of the solid solution are systematically investigated after the ceramics have been quenched from a high *** find that the ferromagnetism of the quenched ceramics is greatly *** enhanced piezoelectric response d33 larger than 200 pC/N,which could be sustained up to 350℃,is *** a result of enhanced ferromagnetism and piezoelectric response,a large magnetoelectric response^1.3 V/cm·Oe(1 Oe=79.5775 A·m^-1)is obtained near the mechanical resonance frequency of the quenched ceramic *** research also shows that in addition to the ferromagnetism and piezoelectric response,the mechanical quality factor is another important parameter to achieve high magnetoelectric response because the physical effects are coupled through mechanical interaction in BiFeO3-based *** work suggests that quenching is an effective approach to enhancing the magnetoelectric response of BiFeO3-based materials and the materials belong to single-phase multiferroic materials with high magnetoelectric response.

关键词： multiferroic materials magnetoelectric ferromagnetic piezoelectric

Mechanism of Affecting the Performance and Stability of an Axial Flow Compressor with Inlet Distortion

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Journal of Thermal Science 2021年第4期30卷 1406-1420页

作者： ZHANG Haoguang LI qi DONG Feiyang chu Wuli School of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China

The purpose of the investigation is to obtain the mechanism of affecting the performance and stability of an axial flow compressor with two kinds of multi distortion *** the investigation,the compressor inlet distortion is made by the distortion generator,which is a column and is placed in the compressor rotor passage *** five-passages unsteady numerical results show that the compressor performances for two kinds of multi distortion area are both lower than that for the clean inlet,and the compressor peak efficiencies for inlet distortions of 6×12 degrees and 6×24 degrees are about 3.5%,and 9.2%lower than that for the clean inlet,***,two kinds of multi distortion area both reduce the compressor stability,and the stall margin improvements of–2.93%and–6.11%are provided by inlet distortions of 6×12 degrees and 6×24 degrees,*** flow field analyses show that the flow conditions of the rotor tip inlet upstream deteriorate after the application of multi distortion *** values of axial velocity and flow angle of incoming flows in some regions,which are near the shroud,become small due to the adverse effect made by the inlet ***,the circulation capacity of the regions becomes low,and inlet blockages appear in some rotor tip *** bigger the distorted range is,the greater inlet blockages and corresponding flow losses *** multi distortion area changes from 6×12 degrees to 6×24 degrees,there are obvious separations of the boundary layer near the blade suction surface in some blade tip passages,and the serious separations prevent the incoming flows from entering the blade tip *** a result,overflows occur at the leading edge of the blade ***,as the number of the distortion generator increases by a factor of one,the effects of inlet distortion on the amplitudes of the air relative velocity and static pressure in the rotor inlet upstream at the distortion generator passing frequency of 1076.5 Hz

关键词： axial flow compressor stability performance multi distortion area separation

Robust control for constant thrust rendezvous under thrust failure

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Chinese Journal of Aeronautics 2015年第2期28卷 518-526页

作者： qi Yongqiang jia Yingmin Wang jian College of Sciences China University of Mining and Technology School of Automation Science and Electrical Engineering Beihang University School of Environment Science and Spatial Informatics China University of Mining and Technology

A robust constant thrust rendezvous approach under thrust failure is proposed based on the relative motion dynamic model. Firstly, the design problem is cast into a convex optimization problem by introducing a Lyapunov function subject to linear matrix inequalities. Secondly, the robust controllers satisfying the requirements can be designed by solving this optimization problem. Then, a new algorithm of constant thrust fitting is proposed through the impulse compensation and the fuel consumption under the theoretical continuous thrust and the actual constant thrust is cal- culated and compared by using the method proposed in this paper. Finally, the proposed method having the advantage of saving fuel is proved and the actual constant thrust switch control laws are obtained through the isochronous interpolation method, meanwhile, an illustrative example is pro- vided to show the effectiveness of the proposed control design method.

关键词： Constant thrust Optimal fuel Rendezvous Robust controller Thrust failure

Kernel semi-supervised graph embedding model for multimodal and mixmodal data

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Science China(Information Sciences) 2020年第1期63卷 247-249页

作者： qi ZHANG Rui LI Tianguang chu School of Information Technology & Management University of International Business & Economics Key Laboratory of Machine Perception(Ministry of Education) Peking University School of Mathematical Sciences Dalian University of Technology State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University

Dear editor,Semi-supervised learning has obtained increasing interests in machine learning, because making use of both labeled and unlabeled training samples helps extracting discriminative features and meanwhile reduces the time-consuming and labor-intensive labeling burden. For extracting features upon multimodal (i.e., data of the same

关键词： Kernel semi-supervised graph embedding model for multimodal and mixmodal data

Optimal redundancy allocation for reliability systems with imperfect switching

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Journal of Systems Engineering and Electronics 2014年第2期25卷 332-339页

作者： Lun Ran Jinlin Li Xujie jia Hongrui chu School of Management and Economics Beijing Institute of Technology College of Science Minzu University of China

The problem of stochastically allocating redundant com- ponents to increase the system lifetime is an important topic of reliability. An optimal redundancy allocation is proposed, which maximizes the expected lifetime of a reliability system with sub- systems consisting of components in parallel. The constraints are minimizing the total resources and the sizes of subsystems. In this system, each switching is independent with each other and works with probability p. Two optimization problems are studied by an incremental algorithm and dynamic programming technique respectively. The incremental algorithm proposed could obtain an approximate optimal solution, and the dynamic programming method could generate the optimal solution,

关键词： optimal redundancy allocation parallel imperfectswitching incremental algorithm dynamic programming.