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Love wave propagation in one-dimensional piezoelectric quasicrystal multilayered nanoplates with surface effects

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 619-632页

作者： xin FENG Liaoliang KE Yang GAO College of Science China Agricultural UniversityBeijing 100083China School of Mechanical Engineering Tianjin UniversityTianjin 300350China

The exact solutions for the propagation of Love waves in one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)nanoplates with surface effects are *** electro-elastic model is developed to investigate the anti-plane strain problem of Love wave *** introducing three shape functions,the wave equations and electric balance equations are decoupled into three uncorrelated *** the boundary conditions of the top surface on the covering layer,the interlayer interface,and the matrix,a dispersive equation with the influence of multi-physical field coupling is provided.A surface PQC model is developed to investigate the surface effects on the propagation behaviors of Love waves in quasicrystal(QC)multilayered structures with nanoscale thicknesses.A novel dispersion relation for the PQC structure is derived in an explicit closed form according to the non-classical mechanical and electric boundary *** examples are given to reveal the effects of the boundary conditions,stacking sequence,characteristic scale,and phason fluctuation characteristics on the dispersion curves of Love waves propagating in PQC nanoplates with surface effects.

关键词： piezoelectric quasicrystal(PQC)material multilayered plate dispersion characteristic surface effect

Repair tolerance assessment for aircraft composite structures using Bayesian updating

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Chinese Journal of Aeronautics 2024年第6期37卷 360-391页

作者： xin LI Hongfu ZUO Bin YANG School of Automotive and Rail Transit Nanjing Institute of TechnologyNanjing 211167China Civil Aviation Key Laboratory of Aircraft Health Monitoring and Intelligent Maintenance College of Civil AviationNanjing University of Aeronautics and AstronauticsNanjing 211106China

Detection and repair of composite damage is crucial to ensure the safety and reliability of aircraft structures.A novel approach to quantitatively evaluate the repair tolerance of composite structures in civil aircraft based on Bayesian updating is *** method incorporates historical damage inspection data to determine the prior distribution of damage size,which is then updated with newly collected damage size data using Bayesian *** Carlo simulation is employed to investigate the probability of failure and estimate maintenance costs,considering various factors such as the frequency and timing of damage events,damage detection,structural strength,gust loads,and maintenance expenses throughout the lifecycle of composite *** and economic factors are considered to establish a lower threshold for repairs and an upper threshold for maintenance based on the occurrence of accidental impact *** of the effectiveness and feasibility of a quantitative assessment method for repair tolerance is conducted using damage statistics data from civil aircraft routes utilizing the structural skin panels of composite outer *** results demonstrate that the method proposed in conjunction with extensive simulations and full utilization of field damage inspection data can effectively simulate unexpected impact damage situations that may occur during civil aircraft service and evaluate the reliability and economic feasibility of the repair of *** research findings hold significant theoretical and practical value for the preparation of documents for continued airworthiness of composite structures,including structural repair manuals and maintenance programs.

关键词： Composite structures Repair tolerance Maintenance Bayesian updating Probability of failure

Thermodynamic property of sandwich cylindrical shell structure with metallic wire mesh:Numerical modeling and experimental analysis

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Chinese Journal of Aeronautics 2024年第1期37卷 138-152页

作者： xin XUE Guojian SHEN Juan LIAO Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China Fujian Shuikou Power Generation Group Co. LTDFuzhou 350000China

As a new addition to lightweight composite structures,the sandwich cylindrical shell with a metallic wire mesh core has emerged as a promising solution for thermodynamic performance analysis at elevated *** intricate interwoven cellular formations within the metallic wire mesh pose difficulties for thermo-mechanical modeling and property ***,the constitutive models employed to characterize hysteresis phenomena were presented,comprising isotropic elasticity,Bergstrom-Boyce model,Ogden hyper-elasticity,and parameter identification through mechanical examinations at varying ***,the finite element modeling of cylindrical shell structures was determined for modal and steady-state dynamic ***,the experimental procedures were carried out,including the preparation of the sandwich cylindrical shell and the dynamic testing *** first-order natural frequency of the cylindrical shell structure is close to the resonance frequency of the dynamic test results,with a maximum error of 6.5%,demonstrating the accuracy of the simulation *** compared to the solid-core cylindrical shell,the average insertion loss of the sandwich cylindrical shell structure within the frequency range of 10–1000 Hz at room temperature is up to 11.09 ***,at elevated temperatures,the average insertion loss of the sandwich cylindrical shell decreases but fluctuates as the temperature changes.

关键词： Energy dissipation Metallic matrix composites Numerical analysis Sandwich structure Thermodynamic properties

Interface property of dissimilar Ti-6Al-4V/AA1050 composite laminate made by non-equal channel lateral co-extrusion and heat treatment

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Defence Technology（防务技术） 2024年第3期33卷 197-208页

作者： Juan Liao Mengmeng Tian xin Xue School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350116China

The purpose of this paper is to examine the effect of processing parameters and subsequent heat treatments on the microstructures and bonding strengths of Ti-6Al-4V/AA1050 laminations formed via a non-equal channel lateral co-extrusion *** microstructural evolution and growth mechanism in the diffusion layer were discussed further to optimize the bonding quality by appropriately adjusting process *** electron microscopes(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)were used to characterize interfacial diffusion *** shear test was used to determine the mechanical properties of the interfacial diffusion *** experimental results indicate that it is possible to co-extrusion Ti-6Al-4V/AA1050 compound profiles using non-equal channel lateral *** heat treatment processes affect the thickness of the diffusion *** the temperature and time of heat treatment increase,the thickness of the reaction layers increases ***,the shear strength of the Ti-6Al-4V/AA1050 composite interface is proportional to the diffusion layer *** is observed that a medium interface thickness results in superior mechanical performance when compared to neither a greater nor a lesser interface *** characterization of all heat treatments reveals that the only intermetallic compound observed in the diffusion layers is TiAl_(3..Due to the inter-diffusion of Ti and Al atoms,the TiAl_(3. layer grows primarily at AA1050/TiAl_(3. interfaces.

关键词： Shear strength Co-extrusion Heat treatment Microstructure Intermetallic compounds

SOLVING OPTIMIZATION PROBLEMS OVER THE STIEFEL MANIFOLD BY SMOOTH EXACT PENALTY FUNCTIONS

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Journal of Computational Mathematics 2024年第5期42卷 1246-1276页

作者： Nachuan Xiao xin Liu The Institute of Operations Research and Analytics National University of SingaporeSingapore State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of Sciencesand University of Chinese Academy of SciencesChina

In this paper,we present a novel penalty model called ExPen for optimization over the Stiefel *** from existing penalty functions for orthogonality constraints,ExPen adopts a smooth penalty function without using any first-order derivative of the objective *** show that all the first-order stationary points of ExPen with a sufficiently large penalty parameter are either feasible,namely,are the first-order stationary points of the original optimization problem,or far from the Stiefel ***,the original problem and ExPen share the same second-order stationary ***,the exact gradient and Hessian of ExPen are easy to *** a consequence,abundant algorithm resources in unconstrained optimization can be applied straightforwardly to solve ExPen.

关键词： Orthogonality constraint Stiefel manifold Penalty function

A sub-grid scale model for Burgers turbulence based on the artificial neural network method

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Theoretical & Applied Mechanics Letters 2024年第3期14卷 162-165页

作者： xin Zhao Kaiyi Yin Department of Mechanics Beijing Institute of TechnologyBeijing 100081China

The present study proposes a sub-grid scale model for the one-dimensional Burgers turbulence based on the neuralnetwork and deep learning *** filtered data of the direct numerical simulation is used to establish thetraining data set,the validation data set,and the test data *** artificial neural network(ANN)methodand Back Propagation method are employed to train parameters in the *** developed ANN is applied toconstruct the sub-grid scale model for the large eddy simulation of the Burgers turbulence in the *** proposed model well predicts the time correlation and the space correlation of the Burgers turbulence.

关键词： Artificial neural network Back propagation method Burgers turbulence Large eddy simulation Sub-grid scale model

Hawking-Page transition and the dual relations of anti-de Sitter black holes surrounded by dark energy in general dimensions

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Communications in Theoretical Physics 2024年第7期76卷 94-104页

作者： Zhang xin Xu Wei School of Mathematics and Physics China University of GeosciencesWuhan 430074China

Recently,a dual relation T_(0)(n+1)=T_(HP)(n)between the minimum temperature(T_(0)(n+1))black hole phase and the Hawking-Page transition(T_(HP)(n))black hole phase in two successive dimensions was introduced by Wei et al(2020 ***.D10210411);this was reminiscent of the anti-de Sitter/conformal field theory(AdS/CFT)correspondence,as the Hawking-Page transition temperature could be treated as the temperature of the dual physical quantity on the boundary and the latter corresponds to that in the *** this paper,we discuss the Hawking-Page transition and the dual relations in Ads black holes surrounded by dark energy in general *** findings reveal the occurrence of the Hawking-Page transition between the thermal AdS radiation and thermodynamically stable large AdS black holes,in both the spacetime surrounded by phantom dark energy and the spacetime surrounded by quintessence dark *** discuss the effects of the phantom dark energy and quintessence dark energy on the Hawking-Page transition *** the dual relation in particular,it works well for the case of an AdS black holes surrounded by phantom dark *** the case of an Ads black hole surrounded by quintessence dark energy,the dual relation should be modified under an open assumption that the state parameter and the density parameter of the quintessence dark energy depend on the dimensions of the spacetime.

关键词： Hawking-Page transition dark energy black hole thermodynamics

Experimental and numerical study on protective effect of RC blast wall against air shock wave

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Defence Technology（防务技术） 2024年第1期31卷 567-579页

作者： xin-zhe Nian Quan-min Xie xin-li Kong Ying-kang Yao Kui Huang State Key Laboratory of Precision Blasting Jianghan UniversityWuhan430056China Hubei Key Laboratory of Blasting Engineering Jianghan UniversityWuhan430056China Hubei(Wuhan)Institute of Explosion and Blasting Technology Jianghan UniversityWuhan430056China College of Defense Engineering Army Engineering University of PLANanjing210007China Institute of Defense Engineering AMSPLALuoyang471023China

Prototype experiments were carried out on the explosion-proof performance of the RC blast *** mass of TNT detonated in the experiments is 5 kg and 20 kg *** shock wave overpressure was tested in different *** above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP *** results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP *** dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was *** to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are *** above results can provide a reference for the design and construction of the reinforced concrete blast wall.

关键词： Blast wall Shock wave Diffraction Overpressure Protection

Composition operators on weighted Bergman spaces induced by doubling weights

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Science China Mathematics 2024年第7期67卷 1571-1598页

作者： xin Guo Maofa Wang School of Mathematics and Statistics Wuhan UniversityWuhan430072China

Given a doubling weightωon the unit disk D,let A_(ω)^(p) be the space of all the holomorphic functions f,where∥f∥A_(ω)^(p):=(∫_(D)|f(z)|_(p)ω(z)dA(z))^(1/p)<∞.We completely characterize the topological connectedness of the set of composition operators on A_(ω)^(p).As an application,we construct an interesting example which reveals that two composition operators on A_(α)^(p) in the same path component may fail to have a compact difference and give a negative answer to the Shapiro-Sundberg question in the(standard)weighted Bergman *** addition,we completely describe the central compactness of any finite linear combinations of composition operators on A_(ω)^(p) in three terms:a Julia-Carathéodory-type function-theoretic characterization,a power-type characterization,and a Carleson-type measure-theoretic characterization.

关键词： composition operator linear combination linearly connected weighted Bergman space doubling weight