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THE APPROXIMATION SOlUTIONS FOR HIGHER DIMENSIONAl INTEGRO-DIFFERENTIAl EQUATIONS

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Acta Mathematica Scientia 2019年第5期39卷 1309-1318页

作者： lüping chen School of Mathematical Sciences Xiamen University

This work deals with approximation solutions to a type of integro-differential equations in several complex variables. It concerns the Cauchy formula on higher dimensional domains. In our study, we make use of multiple power series expansions and an iterative computation method to solve a kind of integro-differential equation. We introduce a symmetrized topology product area which is called a bicylinder. We expand functions and derivatives of them to power series. Moreover we obtain unknown functions by comparing coefficients of the series on both sides of equations. We express the approximation solutions by a regular product of matrixes.

关键词： integro-differential equations polynomial approach Cauchy formula bicylinder

Photoelectrochemical Study of Passive Films on Sensitized Stainless Steel

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Journal of Materials Science & Technology 1996年第5期12卷 381-384页

作者： Du, TB chen, SH Yang, MZ chen, l BEIJING UNIV DEPT CHEMBEIJING 100871PEOPLES R CHINA

Passive films formed on sensitized stainless steel in sulphuric acid solutions have been studied using photoelectrochemical techniques. The results of the photocurrent measurement indicate that the passive films on sensitized stainless steel are characterised with n-type or p-type semiconductor in different potential regions. The difference in the photoelectrochemical behaviour can be interpreted assuming that the passive film is an iron-chromium oxide solid solution associated with various hydration degrees of the Cr(III)-oxides at various potentials.

关键词： Protective coatings

NUMERICAl SIMUlATION OF SUCCINONITRITE DENDRITIC GROWTH IN A FORCED FlOW

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Acta Metallurgica Sinica(English letters) 2008年第6期21卷 444-450页

作者： Z. chen C.l. chen l.M. Hao School of Science Department of Applied Physics Shaanxi Key Laboratory of Condensed Matter Structures and Properties Northwestern Polytechnical University Xi＇an 710072 China School of Science Xi＇an University of Science ＆ Technology Xi＇an 710054 China

Numerical simulation based on phase field method is performed to describe solidification process of pure material in a free or forced flow. The evolution of the interface is showed, and the effects of mesh grid and flow velocity on succinonitrite shape are studied. These results indicate that crystal grows into an equiaxial dendrite in a free flow and into an asymmetrical dendritic in a forced flow. With increasing flow velocity, the upstream dendritic arm tip grows faster and the downstream arm grows slower. However, the evolution of the perpendicular tip has no significant change. In addition, mesh grid has no influence on dendritic growth shape when mesh grid is above 300×300.

关键词： Phase field method Forced flow Dendritic Succinonitrite Tip velocity

INTERNAl FRICTION AND ElASTIC CONSTANTS OF Pd-B-H AllOYS

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Acta Metallurgica Sinica(English letters) 1998年第1期11卷 51-55页

作者： Y.l.chen Zhejiang Univ Hangzhou China

Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B alloys at 220K and measuring frequencies of about 4Hz could not be established at a frequency of 15MH. Ternary Pd-B-H alloys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.

关键词： Pd-B-H alioy,internal friction,elastic constant Zener effect

Tensile and cyclic deformation response of friction-stir-welded dissimilar aluminum alloy joints:Strain localization effect

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Journal of Materials Science & Technology 2021年第14期73卷 91-100页

作者： P.l.Niu W.Y.li D.l.chen State Key laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi'an710072.China Department of Mechanical and Industrial Engineering Ryerson University350 Victoria StreetTorontoOntarioM5B2K3Canada

Cyclic deformation behavior of friction-stir-welded dissimilar AA2024-T351 to AA7075-T65 aluminum alloy joints was evaluated via stepwise tests at different strain rates,along with transmission electron microscopy examinations to characterize the precipitates required to assess internal *** backscatter diffraction was employed to observe the inhomogeneous microstructures of the FSWed *** localization appeared in the heat affected zone(HAZ)of AA2024 *** cyclic deformation of 500 cycles at a total strain amplitude of 0.5%,the strength of the dissimilar joints resumed basically to that of AA2024 base *** the AA2024 HAZ was obviously hardened,which should be attributed to the introduced dislocations during cyclic deformation *** hardening capacity of the joints increased with decreasing strain rate.

关键词： Friction stir welding Dissimilar aluminum alloys Strain localization Cyclic hardening Slip irreversibility

Integral Barrier lyapunov function-based adaptive control for switched nonlinear systems

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Science China(Information Sciences) 2020年第3期63卷 212-225页

作者： lei lIU Yan-Jun lIU Aiqing chen Shaocheng TONG C.l.Philip chen College of Science Liaoning University of Technology Computer Science and Engineering South China University of Technology Navigation College Dalian Maritime University

This paper presents an adaptive control method for a class of uncertain strict-feedback switched nonlinear systems. First, we consider the constraint characteristics in the switched nonlinear systems to ensure that all states in switched systems do not violate the constraint ranges. Second, we design the controller based on the backstepping technique, while integral Barrier lyapunov functions(i BlFs) are adopted to solve the full state constraint problems in each step in order to realize the direct constraints on state ***, we introduce the lyapunov stability theory to demonstrate that the adaptive controller achieves the desired control goals. Finally, we perform a numerical simulation, which further verifies the significance and feasibility of the presented control scheme.

关键词： adaptive control switched nonlinear systems integral Barrier lyapunov functions backstepping technique full state constraints

Finite element implementation of strain-hardening Drucker-Prager plasticity model with application to tunnel excavation

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Underground Space 2017年第3期2卷 168-174页

作者： K.liu S.l.chen Department of Civil&Environmental Engineering Louisiana State UniversityBaton RougeLAUSA

This paper presents a finite element implementation of a strain-hardening Drucker-Prager model and its application to tunnel *** computational model was constructed based on the return mapping scheme,in which an elastic trial step was first executed,followed by plastic correction involving the Newton-Raphson method to return the predicted state of stresses to the supposed yield *** combining the plastic shear hardening rule and stress correction equations,the loading index for the strain-hardening Drucker-Prager model was *** is therefore possible to update the stresses,elastic and plastic strains,and slope of the yield locus at the end of each incremental *** an illustrative example,an integration algorithm was incorporated into ABAQUS through the user subroutine UMAT to solve the tunnel excavation problem in strain-hardening Drucker-Prager rock *** obtained numerical results were found to be in excellent agreement with the available analytical solutions,thus indicating the validity and accuracy of the proposed UMAT code,as well as the finite element model.

关键词： Strain-hardening Drucker-Prager model Finite element method UMAT code Tunnel excavation

Performance analysis of fuzzy BlS using different cluster methods for classification

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Science China(Information Sciences) 2021年第4期64卷 232-234页

作者： Shuang FENG C.l.Philip chen School of Applied Mathematics Beijing Normal University Faculty of Science and Technology University of Macau

Dear editor,Neural networks (NNs) and fuzzy systems are commonly used computational intelligence techniques, each with their own merits in terms of applications. The integration of NNs and fuzzy systems, which leads to a hybrid framework known as neuro-fuzzy systems, inherits the useful properties of its constituents:the learning power of an NN and the knowledge representation of a fuzzy inference system,

关键词： Information Systems and Communication Service

A Multiple Feature Approach for Disorder Normalization in Clinical Notes

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Wuhan University Journal of Natural Sciences 2016年第6期21卷 482-490页

作者： lü chen chen Bo lü Chaozhen QIU likun JI Donghong School of Computer Wuhan University Department of Chinese language and literature Hubei University of Art and Science Shandong Key lab of language Resource Development and Application Ludong University

In this paper we propose a multiple feature approach for the normalization task which can map each disorder mention in the text to a unique unified medical language system（UMlS）concept unique identifier（CUI）. We develop a two-step method to acquire a list of candidate CUIs and their associated preferred names using UMlS API and to choose the closest CUI by calculating the similarity between the input disorder mention and each candidate. The similarity calculation step is formulated as a classification problem and multiple features（string features,ranking features,similarity features,and contextual features） are used to normalize the disorder mentions. The results show that the multiple feature approach improves the accuracy of the normalization task from 32.99% to 67.08% compared with the Meta Map baseline.

关键词： natural language processing disorder normalization levenshtein distance semantic composition multiple features