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Nano-Micro Letters 2025年第1期17卷 191-204页

作者： Zizhuang He Lingzi Shi Ran Sun Lianfei Ding Mukun He Jiaming Li Hua Guo Tiande Gao Panbo Liu school of Chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi’an 710129People’s Republic of China school of Marine Science and Technology Northwestern Polytechnical UniversityXi’an 710072People’s Republic of China

Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase ***,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation *** results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial ***,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic ***,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon *** design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.

关键词： Magnetic heterointerfaces Phase evolution Interfacial polarization Magnetic coupling Electromagnetic wave absorption

Thermoelastic analysis of multiple defects with the extended finite element method

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Acta Mechanica Sinica 2016年第6期32卷 1123-1137页

作者： Honggang Jia Yufeng Nie school of mathematics and statistics Xuchang University school of Science Northwestern Polytechnical University

In this paper, the extended finite element method (XFEM) is adopted to analyze the interaction between a single macroscopic inclusion and a single macroscopic crack as well as that between multiple macroscopic or microscopic defects under thermal/mechanical load. The effects of different shapes of multiple inclusions on the material thermomechanical response are investigated, and the level set method is coupled with XFEM to analyze the interaction of multiple defects. Further, the discretized extended finite element approximations in relation to thermoelastic problems of multiple defects under displacement or temperature field are given. Also, the interfaces of cracks or materials are represented by level set functions, which allow the mesh assignment not to conform to crack or material interfaces. Moreover, stress intensity factors of cracks are obtained by the interaction integral method or the M-integral method, and the stress/strain/stiffness fields are simulated in the case of multiple cracks or multiple inclusions. Finally, some numerical examples are provided to demonstrate the accuracy of our proposed method.

关键词： Multiple defects Stress intensity factors extended finite element method (XFEM) Thermoelastic

Estimation for constant-stress accelerated life test from generalized half-normal distribution

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Journal of Systems Engineering and Electronics 2017年第4期28卷 810-816页

作者： Liang Wang Yimin Shi school of mathematics and statistics Xidian University Department of Applied mathematics Northwestern Polytechnical University

In the constant-stress accelerated life test, estimation issues are discussed for a generalized half-normal distribution under a log-linear life-stress model. The maximum likelihood estimates with the corresponding fixed point type iterative algorithm for unknown parameters are presented, and the least square estimates of the parameters are also proposed. Meanwhile, confidence intervals of model parameters are constructed by using the asymptotic theory and bootstrap technique. Numerical illustration is given to investigate the performance of our methods.

关键词： accelerated life test maximum likelihood estimation least square method bootstrap technique asymptotic distribution

Mutation detection and fast identification of switching system based on data-driven method

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Chinese Physics B 2023年第5期32卷 164-177页

作者：张钟化徐伟宋怡 school of mathematics and statistics Northwestern Polytechnical UniversityXi’an 710072China

In the engineering field,switching systems have been extensively studied,where sudden changes of parameter value and structural form have a significant impact on the operational performance of the ***,it is important to predict the behavior of the switching system,which includes the accurate detection of mutation points and rapid reidentification of the ***,few efforts have been contributed to accurately locating the mutation *** this paper,we propose a new measure of mutation detection—the threshold-based switching index by analogy with the Lyapunov *** give the algorithm for selecting the optimal threshold,which greatly reduces the additional data collection and the relative error of mutation *** the system identification part,considering the small data amount available and noise in the data,the abrupt sparse Bayesian regression(abrupt-SBR)method is *** method captures the model changes by updating the previously identified model,which requires less data and is more robust to noise than identifying the new model from *** two representative dynamical systems,we illustrate the application and effectiveness of the proposed *** research contributes to the accurate prediction and possible control of switching system behavior.

关键词： mutation detection switching index system identification sparse Bayesian regression

A drag force formula for heterogeneous granular flow systems based on finite average statistical method

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Particuology 2021年第2期19卷 94-107页

作者： Xin Li Jie Ouyang Xiaodong Wang Panpan Chu school of mathematics and statistics Northwestern Polytechnical UniversityXi’an 710129China

The existing drag models are mostly based on the assumption of homogenous ***,the use of a homogeneous drag model to predict a heterogeneous granular flow system will cause a *** this study,we developed a drag force model based on the assumption of heterogeneous *** prevent weakening of the heterogeneous characteristics in the drag force formula,we propose a finite average statistical method to filter the information of the heterogeneous granular *** filtered information was used to fit the modified drag formula,which can reflect the heterogeneity of the granular cluster considering different configurations.A comparison shows that the new proposed drag formula filtered by the finite average statistical method fits well with energy minimization multi-scale simulation results.

关键词： Granular flow Drag force Heterogeneous Lattice Boltzmann method Finite average statistical method

Most probable transition paths in eutrophicated lake ecosystem under Gaussian white noise and periodic force

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Chinese Physics B 2022年第6期31卷 155-162页

作者： Jinlian Jiang Wei Xu Ping Han Lizhi Niu school of mathematics and statistics Northwestern Polytechnical UniversityXi’an 710072China

The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are *** the existing work in detecting early warning signals,this paper presents the most probable transition paths to characterize the regime *** most probable transition paths are obtained by minimizing the Freidlin-Wentzell(FW)action functional and Onsager-Machlup(OM)action functional,*** most probable path shows the movement trend of the lake eutrophication system under noise excitation,and describes the global transition behavior of the *** the excitation of Gaussian noise,the results show that the stability of the eutrophic state and the oligotrophic state has different results from two perspectives of potential well and the most probable transition *** the excitation of Gaussian white noise and periodic force,we find that the transition occurs near the nearest distance between the stable periodic solution and the unstable periodic solution.

关键词： eutrophicated lake ecosystem Freidlin-Wentzell action functional Onsager-Machlup action functional most probable transition path

The General Compromise Value for Cooperative Games With Transferable Utility

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Journal of Systems Science & Complexity 2023年第1期36卷 375-392页

作者： SUN Panfei HOU Dongshuang SUN Hao school of mathematics and statistics Northwestern Polytechnical UniversityXi’an 710101China

The authors introduce the general compromise value for cooperative games with transferable *** respect to a set of potential payoffs of which the maximal and minimal potential payoff vectors are regarded as the upper and lower bounds for players,the unique pre-imputation lying on the straight line segment with these two vectors as the extreme points is defined as the general compromise ***-consistency and maximal proportional property are introduced to characterize the general compromise value.

关键词： Axiomatization compromise value cooperative game solution concept

Stochastic bifurcations of generalized Duffing–van der Pol system with fractional derivative under colored noise

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Chinese Physics B 2017年第9期26卷 62-69页

作者：李伟张美婷赵俊锋 school of mathematics and statistics Xidian University Applied mathematics Department School of ScienceNorthwestern Polytechnical University

The stochastic bifurcation of a generalized Duffing–van der Pol system with fractional derivative under color noise excitation is studied. Firstly, fractional derivative in a form of generalized integral with time-delay is approximated by a set of periodic functions. Based on this work, the stochastic averaging method is applied to obtain the FPK equation and the stationary probability density of the amplitude. After that, the critical parameter conditions of stochastic P-bifurcation are obtained based on the singularity theory. Different types of stationary probability densities of the amplitude are also obtained. The study finds that the change of noise intensity, fractional order, and correlation time will lead to the stochastic bifurcation.

关键词： stochastic bifurcation fractional derivative color noise stochastic averaging method

Effect of hygrothermal aging on moisture diffusion and tensile behavior of CFRP composite laminates

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Chinese Journal of Aeronautics 2023年第3期36卷 382-392页

作者： Yong DU Yu’e MA Wenbo SUN Zhenhai WANG school of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China school of mathematics and statistics Northwestern Polytechnical UniversityXi’an 710129China

Carbon Fiber Reinforced Polymer(CFRP)composites are widely used in aircraft structures,because of their superior mechanical and lightweight *** composites are often exposed to hygrothermal environments in *** and moisture can affect the material properties of *** order to make clear the moisture diffusion behavior and the properties degradation of composites,the TG800/E207 composite laminates with four stacking sequences[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sare designed and *** absorption tests are carried out at 80℃,90%*** is shown that the moisture absorption curves of composite laminates present a three-stage.A modified Fickian model was proposed to capture the diffusion behavior of TG800/E207 composite *** relationships among the non-Fickian parameters,the environmental parameters and the stacking sequences of CFRP were correlated and *** showed that the modified Fickian curve is sensitive to the diffusivity of Stage Ⅰ and Stage Ⅱ.Compared with unaged specimens,the maximum tensile stress for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 14.94%,28.15%,11.96%,and 26.36%,*** strains at failure for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 55.38%,62.65%,46.41%,and31.71%,*** elastic modulus for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sincreased by 90.93%,94.57%,49.22%,and 8.22%,respectively.[90]16sample has the minimum saturated moisture content and the maximum strength degeneration.

关键词： CFRP Hygrothermal aging Moisture diffusion Stacking sequence Tensile behavior

Control of epileptic activities in a cortex network of multiple coupled neural populations under electromagnetic induction

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Applied mathematics and Mechanics(English Edition) 2023年第3期44卷 499-514页

作者： Zhongkui SUN Yuanyuan LIU Xiaoli YANG Wei XU school of mathematics and statistics Northwestern Polytechnical UniversityXi’an 710129China school of mathematics and statistics Shaanxi Normal UniversityXi’an 710062China

Epilepsy is believed to be associated with the abnormal synchronous neuronal activity in the brain,which results from large groups or circuits of *** this paper,we choose to focus on the temporal lobe epilepsy,and establish a cortex network of multiple coupled neural populations to explore the epileptic activities under electromagnetic *** demonstrate that the epileptic activities can be controlled and modulated by electromagnetic induction and coupling among *** certain regions,these two types of control are observed to show exactly reverse *** results show that the strong electromagnetic induction is conducive to eliminating the epileptic *** coupling among regions has a conduction effect that the previous normal background activity of the region gives way to the epileptic discharge,owing to coupling with spike wave discharge ***,these results highlight the role of electromagnetic induction and coupling among the regions in controlling and modulating epileptic activities,and might provide novel insights into the treatments of epilepsy.

关键词： epilepsy electromagnetic induction multiple coupled neural population dynamical transition