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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

Microstructure and dislocation structure evolution during creep life of Ni-based single crystal superalloys

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Journal of Materials Science & Technology 2020年第10期42卷 207-214页

作者： Hao Yu wei xu Sybrand van der Zwaag Novel Aerospace Materials Group Faculty of Aerospace EngineeringDelft University of Technology2629HSDelftthe Netherlands State Key Laboratory of Rolling and Automation Northeastern University110819ShenyangChina

The high performance of Ni single crystal superalloys during high temperature low stress creep service,is intrinsically determined by the combined effects of microstructural evolution and the dislocation *** the field of the evolution of dislocation network,two main recovery mechanism based on dislocation migration dominate the *** is superdislocations shearing intoγ’rafts through a two-superpartials-assisted *** is the compact dislocations migrating alongγ/γ’*** two mechanisms are similarly climb-rate-controlled *** this work,a model for the minimum creep rate based on thermodynamic and kinetic calculations and using an existing detailed dislocation dynamics model has been built by taking the dislocation migration behaviours as well as the rafted microstructure into consideration,which can well reproduce the([100]tensile)creep properties of existing Ni superalloy grades,without the need to make the dislocation parameter values composition dependent.

关键词： Ni superalloys Microstructure evolution Dislocation behaviour

Effect of work hardening discrepancy on strengthening of laminated Cu/CuZn alloys

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Journal of Materials Science & Technology 2022年第8期103卷 67-72页

作者： Zheng Cao Zhao Cheng wei xu Lei Lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

To clarify the work hardening discrepancy effect on the strengthening of laminated metals,we designed two laminated Cu/Cu4Zn and Cu/Cu32Zn samples with different layer ***/Cu4Zn has larger work hardening discrepancy between two constituent layers relative to Cu/Cu32Zn,but the yield strengths of two Cu Zn constituents are *** tensile results suggest Cu/Cu4Zn with larger work hardening discrepancy exhibits a significant strengthening at early deformation stage while Cu/Cu32Zn possesses a better *** underlying mechanisms for the strengthening effect are attributed to more geometrically necessary dislocations accumulated at interfaces and severer strain localization due to the larger work hardening discrepancy.

关键词： Laminated Cu/Cu alloys Work hardening Strengthening Interfacial affected zone Strain localization

Stochastic P-bifurcations of a noisy nonlinear system with fractional derivative element

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Acta Mechanica Sinica 2021年第3期37卷 507-515,I0004页

作者： Ya-Hui Sun Yong-Ge Yang wei xu School of Applied Mathematics Guangdong University of TechnologyGuangzhou 510520China Department of Applied Mathematics Northwestern Polytechnical UniversityXi'an 710072China

This paper investigates the stochastic P-bifurcation(SPB)of a fractionally damped oscillator subjected to additive and multiplicative Gaussian white *** transformation and the stochastic averaging technique are applied to derive the expression of probability density function(PDF)of the system *** conditions of the stochastic bifurcation induced by system parameters are presented based on the change in the number of extreme points of the probability density *** results are given to show the effectiveness of the proposed *** P-bifurcations for additive and multiplicative noise are studied in detail according to the critical conditions.

关键词： Stochastic P-bifurcation Fractional derivative Stochastic averaging method Gaussian white noise

Numerical Simulation of Tip Clearance Flow Passive Control in Axial Turbine

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Journal of Thermal Science 2008年第2期17卷 147-155页

作者： LI wei QIAO wei-yang xu Kai-fu LUO Hua-ling College of Propulsion and EnergyNorthwestern Polytechnical University Xi＇an 710072 China

This paper focuses on the effects of five different passive turbine tip clearance flow control methods on the tip clearance flow physics, which consists of a partial suction side squealer tip, a double squealer tip, a pressure side tip shelf with inclined squealer tip on a double squealer tip, a tip platform extension edge in pressure side and in suction side respectively. A pressure-correction based, 3D Reynolds-averaged Navier-Stokes equations CFD code with Reynolds Stress Model was adopted. The variable specific heat was considered. The detailed tip clearance flow field with different squealer rims was described with the streamline and the velocity vector. Accordingly, the mechanisms of five passive controls were elucidated; the effects of the passive controls on turbine efficiency and tip clearance flow field were illuminated. The results showed that the secondary flow loss near the outer casing including the tip leakage losses and the passage vortex losses could be reduced in all the five passive control methods. The turbine efficiency could be increased via the rational passive turbine tip clearance flow control. The Improved PS Squealer had the best effect on turbine efficiency, and the efficiency increased by 0.215%.

关键词： contact face wave receiving tube absorber

Reliability and control of strongly nonlinear vibro-impact system under external and parametric Gaussian noises

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Science China(Technological Sciences) 2020年第9期63卷 1837-1845页

作者： LIU Li xu wei YANG GuiDong HUANG DongMei Department of Applied Mathematics Northwestern Polytechnic UniversityXi’an710072China School of Mathematics and Statistics Ningxia UniversityYinchuan750021China School of Mathematics and Statistics Xidian UniversityXi’an710071China

This paper mainly focuses on reliability and the optimal bounded control for maximizing system reliability of a strongly nonlinear vibro-impact system. Firstly, the new stochastic averaging in which the impact condition is converted to the system energy is applied to obtain the averaged It? stochastic differential equation, by which the associated Backward Kolmogorov(BK)equation and Generalized Pontryagin(GP) equation are derived. Then, the dynamical programming equations are obtained based on the dynamical programming principle, by which the optimal bounded control for maximizing system reliability is ***, the effects of the bounded control and noise intensity on the reliability of the vibro-impact system are discussed in detail;meanwhile, the influence of impact conditions on the system's reliability is also studied. The feasibility and effectiveness of the proposed analytical method are substantiated by numerical results obtained from Monte-Carlo simulation.

关键词： vibro-impact system first-passage failure stochastic averaging method stochastic optimal control

Interface control for pure ultraviolet electroluminescence from nano-ZnO-based heterojunction devices

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Science Bulletin 2018年第1期63卷 38-45页

作者： Daotong You Chunxiang xu Feifei Qin Zhu Zhu A.Gowri Manohari wei xu Jie Zhao wei Liu State Key Laboratory of Bioelectronics School of Biological Science & Medical Engineering Southeast University

Realization of pure and stable ultraviolet electroluminescence(UV EL) of ZnO light-emitting diode(LED)is still a challenging issue, due to complicated defects of intrinsic ZnO and the corresponding device interfaces. In this paper, we demonstrated a simple & feasible method to fabricate n-ZnO/AlN/p-GaN heterojunctions light-emitting devices. First, the vertically aligned ZnO nanorods(NRs) have been prepared as high quality active layer, and the nanostructured heterojunction LED arrays were constructed by directly bonding ZnO NRs onto AlN-coated p-GaN wafer. By optimizing the AlN layer thickness to be 20 nm, a strong and pure ultraviolet emission located at 387 nm can be observed. The energy band alignment of n-ZnO/AlN(20 nm)/p-Ga N heterojunction LED has been studied by using X-ray photoelectron spectroscopy(XPS), the valence band offset between AlN and GaN was calculated to be 0.34 eV. On the other side, the conduction band offset(as large as 3.28 eV) between Al N and ZnO can block the flow of electrons from ZnO top-GaN. Thus, electron-hole recombination takes place in the ZnO layer, and a pure UV EL could be observed. Our results provide a significant approach toward future of pure ultraviolet optoelectronic LEDs.

关键词： ZnO nanorods AlN insulator layer Interface control Pure ultraviolet light emitting diode Directly bonding

Subband Light Emission from Phosphorous-Doped Amorphous Si/SiO_(2) Multilayers at Room Temperature

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Chinese Physics Letters 2011年第6期28卷 291-294页

作者： SUN Hong-Cheng xu Jun LIU Yu MU wei-wei xu wei LI wei CHEN Kun-Ji Nanjing National Laboratory of Microstructures Key Laboratory of Advanced Photonic and Electronic MaterialsSchool of Electronic Science and EngineeringNanjing UniversityNanjing 210093

Phosphorous-doped hydrogenated amorphous Si/SiO2 multilayer structures are fabricated in a plasma enhanced chemical vapor deposition *** microstructural and luminescence properties of the samples are characterized after annealing at various *** the onset crystallization temperature 800–900℃,a strong subband infrared light emission in the range 1.1–1.8μm is observed at room temperature instead of the usually observed visible light *** subband infrared emission is gradually enhanced with the increase of phosphorus doping concentration,which can be ascribed to the increase of the luminescent defect states promoted by the doped phosphorous atoms.

关键词： annealing crystallization amorphous

Exact Solutions and Invariant Sets to General Reaction-Diffusion Equation

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Communications in Theoretical Physics 2008年第6期49卷 1389-1392页

作者： JIA Hua-Bing xu wei Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China

In this paper, we introduce new invariant sets, and the invariant sets and exact solutions to general reactiondiffusion equation are discussed. It is shown that there exist a class of exact solutions to the equations ... 详细信息

关键词： invariant set exact solution general reaction-diffusion equation rotation group scaling group