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Applied Mathematics and Mechanics(English Edition) 2022年第5期43卷 689-708页

作者： Yongbin WANG Huadong YONG youhe ZHOU Department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Key Laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education of ChinaLanzhou UniversityLanzhou 730000China

For the accurate prediction of the effective thermal conductivities of the twisted multi-filamentary superconducting strand,a two-step homogenization method is *** on the distribution of filaments,the superconducting strand can be decomposed into a set of concentric cylinder *** layer is a two-phase composite composed of the twisted filaments and copper *** the first step of homogenization,the representative volume element(RVE)based finite element(FE)homogenization method with the periodic boundary condition(PBC)is adopted to evaluate the effective thermal conductivities of each *** the second step of homogenization,the generalized self-consistent method is used to obtain the effective thermal conductivities of all the concentric cylinder *** accuracy of the developed model is validated by comparing with the local and full-field FE ***,the effects of the twist pitch on the effective thermal conductivities of twisted multi-filamentary superconducting strand are studied.

关键词： superconducting strand multi-filamentary two-step homogenization effective thermal conductivity

VIBRATION SUPPRESSION OF CANTILEVER LAMINATED COMPOSITE PLATE WITH NONLINEAR GIANT MAGNETOSTRICTIVE MATERIAL LAYERS

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Acta Mechanica Solida Sinica 2015年第1期28卷 50-61页

作者： Yongfei Zhang Haomiao Zhou youhe Zhou Key Laboratory of Mechanics on Disaster and Environment in Western China the Ministry of Education of China Lanzhou University Department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou University College of Information Engineering China Jiliang University

In this paper, a nonlinear and coupled constitutive model for giant magnetostrictive materials （GMM） is employed to predict the active vibration suppression process of cantilever laminated composite plate with GMM layers. The nonlinear and coupled constitutive model has great advantages in demonstrating the inherent and complicated nonlinearities of GMM in re- sponse to applied magnetic field under variable bias conditions （pre-stress and bias magnetic field）. The Hamilton principle is used to derive the nonlinear and coupled governing differential equation for a cantilever laminated composite plate with GMM layers. The derived equation is handled by the finite element method （FEM） in space domain, and solved with Newmark method and an iteration process in time domain. The numerical simulation results indicate that the proposed active control system by embedding GMM layers in cantilever laminated composite plate can efficiently suppress vibrations under variable bias conditions. The effects of embedded placement of GMM layers and control gain on vibration suppression are discussed respectively in detail.

关键词： giant magnetostrictive materials nonlinear constitutive model active vibration suppression cantilever laminated composite plate

Degradation of critical current in Bi2212 composite wire under compression load

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Applied Mathematics and Mechanics(English Edition) 2017年第12期38卷 1773-1784页

作者： Zhiyang WANG Huadong YONG youhe ZHOU Key Laboratory of Mechanics on Environment and Disaster in Western China College of Civil Engineering and MechanicsLanzhou UniversityLanzhon 730000China

Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by considering micro-buckling of filament. A Bi2212 wire is regarded as a unidirectional filament-reinforced composite in the theoretical analysis. By considering the influence of inclusion, the micro-buckling wavelength can be derived by using a two-dimensional model. Based on the experimental results, the critical current is fitted as a function of buckling wavelength. It is found that the decrease of the critical current is directly proportional to the reciprocal of square of the buckling wavelength. Change of micro-buckling wavelength with material parameters is discussed. A critical strain in the wire with a filament bridge is analyzed using the finite element method.

关键词： micro-buckling Bi2Sr2Ca1Cu2O8+x(Bi2212) wire wavelength critical current

Contact force and mechanical loss of multistage cable under tension and bending

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Acta Mechanica Sinica 2016年第5期32卷 891-904页

作者： Yanyun Ru Huadong Yong youhe Zhou Key Laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education of China Department of Mechanics and Engineering Sciences College of Civil Engineering and Mechanics Lanzhou University

A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The contact and friction forces between the strands are presented by two-dimensional contact model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including contact force, contact stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the contact force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher contact force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by adjusting the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.

关键词： Contact force Friction force Tension Bending Mechanical loss

Numerical analysis of magnetization AC losses in high-temperature superconducting slabs subjected to uniform strains

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Science China(Technological Sciences) 2014年第4期57卷 765-772页

作者： XIA Jing ZHOU youhe Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China and Department of Mechanics and Engineering Sciences College of Civil Engineering and Mechanics Lanzhou University

High-temperature superconductors in superconductor apparatuses are subjected to mechanical strains under operating *** strains cause the degradation of the critical current densities and influence AC losses in the *** on the dynamic process of thermomagnetic interaction,we report the results of numerical analysis of AC losses in an infinite high-temperature superconducting slab subjected to a uniform in-plane strain in an alternating external magnetic field parallel to the sample *** numerical analysis shows the details of electromagnetic phenomena in the slab and the dependences of AC loss on various external parameters including the uniform strain in the slab and the amplitude and frequency of the external magnetic *** this paper,we find that whether the magnetic field fully penetrates the superconductor is the key factor that influences the features of AC *** the magnetic field cannot fully penetrate the superconductor,the loss rises with increasing strain or decreasing *** the magnetic field can fully penetrate the superconductor,the feature is just *** also analyze the effects of periodic strain on AC *** is interesting to find that when the periodic strain frequency equals the external magnetic field frequency,the AC loss reaches the maximum,regardless if the magnetic field fully penetrates the superconductor or not.

关键词： high-temperature superconducting slab AC loss strain

A simultaneous space-time wavelet method for nonlinear initial boundary value problems

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Applied Mathematics and Mechanics(English Edition) 2018年第11期39卷 1547-1566页

作者： Jizeng WANG Lei ZHANG youhe ZHOU Key Laboratory of Mechanics on Disaster and Environment in Western China the Ministry of Education College of Civil Engineering and Mechanics Lanzhou University

A high-precision and space-time fully decoupled numerical method is developed for a class of nonlinear initial boundary value problems. It is established based on a proposed Coiflet-based approximation scheme with an adjustable high order for the functions over a bounded interval, which allows the expansion coefficients to be explicitly expressed by the function values at a series of single points. When the solution method is used, the nonlinear initial boundary value problems are first spatially discretized into a series of nonlinear initial value problems by combining the proposed wavelet approximation and the conventional Galerkin method, and a novel high-order step-by-step time integrating approach is then developed for the resulting nonlinear initial value problems with the same function approximation scheme based on the wavelet theory. The solution method is shown to have the N th-order accuracy, as long as the Coiflet with [0, 3 N-1]compact support is adopted, where N can be any positive even number. Typical examples in mechanics are considered to justify the accuracy and efficiency of the method.

关键词： nonlinear initial boundary value problem Coiflet numerical method

Effects of charged sand on electromagnetic wave propagation and its scattering field

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Science China(Physics,Mechanics & Astronomy) 2006年第1期49卷 77-87页

作者： HE Qinshu ZHOU youhe ZHENG Xiaojing Department of Mechanics Lanzhou University Gansu 730000 China Department of Mechanics Lanzhou University Gansu 730000 China Department of Mechanics Lanzhou University Gansu 730000 China

Based on the Rayleigh’s scattering theory, the effects of sandstorms on the propagation of electromagnetic wave with different visibilities are presented by solving the scattering field of charged sand particles. Because of the electric charges on the sand surface, the theoretical attenuation will be large enough to match the measured value under certain conditions. And the results show that the effect of sand with electric charges all over its surface on electromagnetic wave attenuation is the same as that of sand without charge, which proves that electric charges distribute on partial surface of the sand in fact.

关键词： scattering field, electromagnetic waves attenuation, wind-blown sand transport, charged sand.

EFFECT OF MAGNETIC NANOPARTICLES ON THE MECHANICAL PROPERTIES OF TYPE-II SUPERCONDUCTORS

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Acta Mechanica Solida Sinica 2014年第1期27卷 65-72页

作者： Chenguang Huang Huadong Yong youhe Zhou Key Laboratory of Mechanics on Environment and Disaster in Western China The Ministry of Education of China and Department of Mechanics and Engineering Sciences School of Civil Engineering and MechanicsLanzhou University

In this paper, the effect of magnetic nanoparticles on the mechanical properties of a type-II superconductor is investigated both theoretically and numerically. Magnetic part of the pinning force associated with the interaction between a finite-size spheroidal magnetic inclusion and an Abrikosov vortex is calculated in the London approximation. It is found that the size and shape of magnetic nanoparticles result in different enhancements of vortex pinning in large-k type-II superconductors. Meanwhile, the screening current induced by a magnetic spheroid suffer the action of Lorentz force, which will lead to prestress in the superconductor, so further numerical calculations are needed to explore the interaction between the spheroidal magnetic particle and superconductor. The distribution of displacement, stress and strain in the superconductor are finally obtained. It is shown that different sizes and shapes of nanoparticles also can change the distributions of these quantities.

关键词： magnetic nanoparticles spheroidal inclusion pinning force stress distribution type-II superconductor

2D/3D MoS_(2)/HTCN异质结制备及光催化固氮综合实验

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实验技术与管理 2024年第1期41卷 44-51页

作者：温福山黄晓栗李亚杰王有和中国石油大学(华东)材料科学与工程学院山东青岛266580 中国石油大学(华东)化学工程学院山东青岛266580

光催化固氮是目前光催化领域的一个重要研究方向。该文利用自组装法合成了2D/3D MoS_(2)/HTCN光催化剂,并通过XRD、XPS、SEM、TEM、UV-vis DRS、PL和EIS等技术对催化剂进行了表征。在模拟太阳光的条件下,进行了光催化固氮的测试,通过控... 详细信息

光催化固氮是目前光催化领域的一个重要研究方向。该文利用自组装法合成了2D/3D MoS_(2)/HTCN光催化剂,并通过XRD、XPS、SEM、TEM、UV-vis DRS、PL和EIS等技术对催化剂进行了表征。在模拟太阳光的条件下,进行了光催化固氮的测试,通过控制变量法对合成氨的氮源进行了研究,并对光催化固氮的机理进行了探讨。该实验包含了多种材料的制备以及测试工作,综合性强、新颖性高,不仅能培养学生在催化剂合成和表征方面的能力,同时注重培养学生的科研思维,全面提高学生的科研素养。

关键词：石墨相氮化碳二硫化钼形貌调控光催化固氮综合实验

Urine—an untapped goldmine for biomarker discovery?

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Science China(Life Sciences) 2013年第12期56卷 1145-1146页

作者： GAO youhe National Key Laboratory of Medical Molecular Biology Department of Physiology and PathophysiologyInstitute of Basic Medical SciencesChinese Academy of Medical Sciences/School of Basic Medicine

The past decade witnessed a few biomarkers discovered and validated;however,biomarker research as a whole has not been fruitful as expected.A majority of our efforts has been focused on blood,the dynamic tissue directly connecting every part of the ***,despite all the interest and endeavor spent on it,the blood has failed to deliver sufficient number of clinically valuable *** it possible that we have been barking up the wrong tree?

关键词：生物标志物金矿开发动态组织临床价值尿