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Numerical investigation on dynamic response of the screen mesh in vibrating screening through DEM-FEM co-simulation

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Particuology 2024年第4期87卷 205-217页

作者： Huan Zhang xiao zheng Weimin Jing Key Laboratory of MetallurgicalEquipment and Control Technology Ministry of EducationWuhan University of Science and TechnologyWuhan430081 China Hubei Key Laboratory of Mechanical Transmssion and Manufacturing Engineering Wuhan University of Science and TechnologyWuhan430081China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing400044China

Dynamic response of the screen mesh is of great significance in the optimum vibrating screen *** this paper,based on the DEM-FEM co-simulation method,the effect of screening parameters on the dynamic response of the screen mesh is explored and the mechanism is revealed on the particle ***,a virtual experiment on a linear vibrating screen was carried out to analyze the screening pa-rameters'effect with both impact load and sustained stress inflicted on the screen ***,the time-domain evolution regularity of the screen mesh LVA(Local Vibration Amplitude)under different particle plugging conditions was investigated based on the ***,the influence of screening parameters on LVA and its distribution was *** results show that the screening parameters can greatly affect the screen mesh LVA and its distribution by changing the movement of the granular material and the particle penetration probability,which provides an important basis for the optimal design of the screen mesh and its supporting structure.

关键词： Vibrating screen Dynamic response DEM-FEM Screening parameters Local vibration amplitude

Phase behavior of undecane–tetradecane mixtures confned in SBA-15

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Chinese Chemical Letters 2013年第10期24卷 885-888页

作者： xiao Yan xiao-zheng Lan College of Chemistry and Materials Science Shandong Agriculture University

Phase behavior of undecane-tetradecane （n-C11H24-C14H3o, C11-C14） mixtures in bulk and confined in SBA-15 have been studied using differential scanning calorimetry. The bulk C11-C14 system shows multiple phase regions due to rotator phase. Confined in the pores of SBA-15 （pore diameters 3.8- 7.8 rim）, the mixtures only show a melting boundary of a straight line and a curve, respectively. In SBA- 15 （ 17.2 nm）, phase behavior of the mixtures has some similarity to that of the bulk. Under confinement, the phase diagrams of the mixtures vary with the pore size, temperature, and compositions.

关键词： Confinement Undecane-tetradecanemixtures Size effect Phase diagram

Time-dependent density-functional theory for open electronic systems

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Science China Chemistry 2014年第1期57卷 26-35页

作者： zheng xiao WANG RuLin Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Department of Physics University of Science and Technology of China

Time-dependent density-functional theory(TDDFT)has been successfully applied to predict excited-state properties of isolated and periodic ***,it cannot address a system coupled to an environment or whose number of electrons is not *** tackle these problems,TDDFT needs to be extended to accommodate open *** paper provides a comprehensive account of the recent developments of TDDFT for open systems(TDDFT-OS),including both theoretical and practical *** practicality and accuracy of a latest TDDFT-OS method is demonstrated with two numerical examples:the time-dependent electron transport through a series of quasi-one-dimensional atomic chains,and the real-time electronic dynamics on a two-dimensional graphene *** advancement of TDDFT-OS may lead to promising applications in various fields of chemistry,including energy conversion and heterogeneous catalysis.

关键词： time-dependent density functional theory,real-time electronic dynamics,hierarchical equations of motion

Blow up of Solutions for a Nonlinear Petrovsky Type Equation with Time-dependent Coefficients

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Acta Mathematicae Applicatae Sinica 2020年第4期36卷 836-846页

作者： xiao-xiao zheng Ya-dong SHANG xiao-ming PENG School of Mathematical Sciences Qufu Normal UniversityQufu 273155China School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006China School of Statistics and Mathematics Guangdong University of Finance and EconomicsGuangzhou 510320China

4In this paper,we study a nonlinear Petrovsky type equation with nonlinear weak damping,a superlinear source and time-dependent coefficients utt+△^2u-ki(t)|ut|m^2ut=k2(t)|u|^p-2u,x∈Ω,t>0,whereΩis a bounded domain in R^*** certain conditions on k1(t),k2(t)and the initial-boundary data,the upper bound for blow-up time of the solution with negative initial energy function is given by means of an auxiliary functional and an energy estimate met hod if p>***,a lower bound of blow-up time are obtained by using a Sobolev-type inequality and a first order differential inequality technique for n=2,3 and n>4.

关键词： nonlinear Petrovsky type equation time-dependent coefficients blow-up upper bound lower bound

Derivation of a second-order model for Reynolds stress using renormalization group analysis and the two-scale expansion technique

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Acta Mechanica Sinica 2011年第5期27卷 649-659页

作者： xiao-Hong Wang zheng-Feng Liu xiao-Xia Lu Department of Thermal Science and Energy Engineering University of Science and Technology of China230026 Hefei China

With the two-scale expansion technique proposed by Yoshizawa,the turbulent fluctuating field is expanded around the isotropic *** a low-order two-scale expansion,applying the mode coupling approximation in the Yakhot-Orszag renormalization group method to analyze the fluctuating field,the Reynolds-average terms in the Reynolds stress transport equation,such as the convective term,the pressure-gradient-velocity correlation term and the dissipation term,are *** numerical examples：turbulent flow past a backward-facing step and the fully developed flow in a rotating channel,are presented for testing the efficiency of the proposed second-order *** these two numerical examples,the proposed model performs as well as the Gibson-Launder （GL） model,giving better prediction than the standard k-ε model,especially in the abilities to calculate the secondary flow in the backward-facing step flow and to capture the asymmetric turbulent structure caused by frame rotation.

关键词： Turbulent modeling Renormalization group Two-scale expansion Reynolds stress transport equation Second-order model

The spatial-temporal evolution of coherent structures in log law region of turbulent boundary layer

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Acta Mechanica Sinica 2015年第1期31卷 16-24页

作者： xiao-Bo zheng Nan.Jiang Department of Mechanics Tianjin University Tianjin Key Laboratory of Modern Engineering Mechanics The State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences

The spatial-temporal evolution of coherent structures （CS） is significant for turbulence control and drag re- duction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was based on a time series of three-dimensional and three-component （3D-3C） velocity fields of the flat plate turbulent boundary layer （TBL） measured by a Tomographic and Time-resolved PIV （Tomo TRPIV） system. Using multi-resolution wavelet transform and conditional sampling method, we extracted the intrinsic topologies and found that the streak structures appear in bar-like patterns. Furthermore, we seized locations and velocity information of transient CS, and then calculated the propagation velocity of CS based on spatial-temporal cross-correlation scanning. This laid a foundation for further studies on relevant dynamics properties.

关键词： Log law region in TBL. Spatial-temporal cross-correlation Tomographic TRPIV Coherent structures Low and high speed streaks Multi-resolution wavelet de-composition

Remark on Mild Solution to the 3D Incompressible Micropolar System in Fourier–Herz Framework

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Acta Mathematica Sinica,English Series 2019年第10期35卷 1595-1616页

作者： Yao NIE xiao Xin zheng School of Mathematics and Systems Science Beihang University

This paper is devoted to investigating the existence and uniqueness of mild solution to the 3D incompressible micropolar fluid system in the Fourier–Herz framework. By taking advantage of microlocal analysis and the mutual effect in the same frequency range of convection term, we give a special initial data(u0,ω0) whose norm of FB1,q^-1(q>2) is arbitrarily small, however, the couple(u0,ω0) produces a solution which is arbitrarily large in FB1,q^-1 after an arbitrarily short time. This implies the system is ill-posed in the sense of "norm inflation" as q>2.

关键词： Ill-posedness micropolar system Fourier-Herz space norm inflation

Low-cycle fatigue lifetime estimation of Ti–6Al–4V welded joints by a continuum damage mechanics model

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Rare Metals 2016年第4期35卷 299-302页

作者： Hong-Yu Qi xiao-Lei zheng xiao-Guang Yang School of Energy and Power Engineering Beihang University Beijing 100191 China

The low-cycle fatigue （LCF） behavior of directionally solidified nickel-based superalloy Ti-6A1-4V was studied under bare and electron beam welding condi- tions at room temperature. Results show that：（1） under the same test conditions, all the joints exhibit lower LCF lifetime than Ti-6A1-4V; （2） the failure of welded structures is mainly ascribed to the welding defect. A novel lifetime prediction methodology based on continuum damage mechanics is proposed to predict the lifetime of Ti-6A1-4V and its welded joints.

关键词： Electron beam welding Low-cycle fatigue Life estimation Continuum damage mechanics

Joint Sample Position Based Noise Filtering and Mean Shift Clustering for Imbalanced Classification Learning

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Tsinghua Science and Technology 2024年第1期29卷 216-231页

作者： Lilong Duan Wei Xue Jun Huang xiao zheng School of Computer Science and Technology Anhui University of TechnologyMaanshan 243032China Institute of Artificial Intelligence Hefei Comprehensive National Science CenterHefei 230088China

The problem of imbalanced data classification learning has received much *** classification algorithms are susceptible to data skew to favor majority samples and ignore minority *** weighted minority oversampling technique(MWMOTE)is an effective approach to solve this problem,however,it may suffer from the shortcomings of inadequate noise filtering and synthesizing the same samples as the original minority *** this end,we propose an improved MWMOTE method named joint sample position based noise filtering and mean shift clustering(SPMSC)to solve these ***,in order to effectively eliminate the effect of noisy samples,SPMsC uses a new noise filtering mechanism to determine whether a minority sample is noisy or not based on its position and distribution relative to the majority *** that MWMOTE may generate duplicate samples,we then employ the mean shift algorithm to cluster minority samples to reduce synthetic replicate ***,data cleaning is performed on the processed data to further eliminate class *** on extensive benchmark datasets demonstrate the effectiveness of SPMsC compared with other sampling methods.

关键词： imbalanced data classification oversampling noise filtering clustering