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The Schwarzian Derivative of Harmonic Mappings in the Plane

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Chinese Annals of Mathematics,Series B 2020年第2期41卷 193-208页

作者： Liping nie Zongxin YANG Institute of Mathematics and Informatics Jiangxi Normal UniversityNanchang 330022China

In this paper, the authors introduce a definition of the Schwarzian derivative of any locally univalent harmonic mapping defined on a simply connected domain in the complex plane. Using the new definition, the authors prove that any harmonic mapping f which maps the unit disk onto a convex domain has Schwarzian norm ||Sf||≤ 6. Furthermore, any locally univalent harmonic mapping f which maps the unit disk onto an arbitrary regular n-gon has Schwarzian norm||Sf||≤8/3.

关键词： Schwarzian derivative Schwarzian norm Harmonic mapping

Bi-stable states of initially stressed elastic cylindrical shell structures with two piezoelectric surface layers

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Acta Mechanica Sinica 2015年第5期31卷 653-659页

作者： Bin Wang Guo-Hua nie Institute of Applied Mechanics School of Aerospace Engineering and Applied MechanicsTongji University

A theoretical model is proposed in this paper to predict the bi-stable states of initially stressed cylindrical shell structures attached by surface anisotropic piezoelectric *** condition for existence of bi-stability of the shell structural system is presented and analytical expressions for corresponding rolled-up radii of the stable shell are given based on the principle of minimum strain *** resulting solution indicates that the shell system may have two stable configurations besides its initial state under a combined action of the actuating electric field and initial stresses characterized by the bending *** the piezoelectric layer materials act as only sensor materials without the actuating electric field,initial stresses may produce the bi-stable states,but one corresponding to its initial *** the shell without initial stresses,the magnitude in the actuating electric field determines the number of the stable states,one or two stable configurations besides the initial *** theoretical prediction for the bi-stable states is verified by finite element method（FEM） simulation by using the ABAQUS code.

关键词： Bi-stable Initial stress Cylindrical shell Piezoelectric layer Elastic potential energy Rolled-up radius Finite element

Scattering Analysis and Optimization of Spherical Acoustic Cloak with Unideal Pentamode Material

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Acta Mechanica Solida Sinica 2020年第3期33卷 347-360页

作者： Xin nie Yi Chen Xiaoning Liu Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationSchool of Aerospace EngineeringBeijing Institute of TechnologyBeijing 100081China

The acoustic scattering is theoretically studied in this paper for three-dimensional spherical cloak composed of unideal pentamode material,for which small shear rigidity is always inevitable for a real designed microstructure.A theoretical formulation is developed to efficiently evaluate the cloaking *** generic scattering feature of the cloak and the efTects of material imperfectness and inner cloak boundary constraints are systematically *** preferable constraint type and the critical imperfectness parameter of the material are identified for possible broadband *** addition,a very practical lining shell scheme is proposed to tune the constraint strength on the inner *** combining the theoretical model with optimization algorithm,it is further proved that the cloak can be reduced by several piecewiseuniform layers and optimized to achieve excellent invisibility in targeted frequency *** study will provide valuable guidance for the future microstructural design of cloaks.

关键词： Pentamode material Spherical acoustic cloak Scattering calculation Boundary effect Optimization

Challenges and strategies of lithium-rich layered oxides for Li-ion batteries

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Nano Research 2023年第1期16卷 391-402页

作者： Lu nie Shaojie Chen Wei Liu School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China

Lithium-ion batteries are considered a promising energy storage technology in portable electronics and electric vehicles due to their high energy density,competitive cost,and environmental *** cathode materials is an effective way to meet the demand for better batteries,of which the utilization of high-voltage cathode materials is an important development *** recent years,lithium-rich layered oxides have gained great attention due to their desirable energy *** review presents the relationships between lattice structure and electrochemical properties,the underlying degradation mechanisms,and corresponding modification *** recent progress and strategies are then highlighted,including element doping,surface coating,morphology design,size control,***,a concise perspective for future developments and practical applications of lithium-rich layered oxides has been provided.

关键词： lithium-ion batteries lithium-rich layered oxides lattice structure degradation mechanism element doping

A Few Frontier Issues in Ocean Engineering Mechanics

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China Ocean Engineering 2021年第1期35卷 1-11页

作者： LI Jia-chun nie Bing-chuan Key Laboratory for Mechanics in Fluid Solid Coupling System Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China Beijing’s Key Laboratory of Structural Wind Engineering and Urban Wind Environment Beijing 100044China

In this review,we primarily address the present state of the arts and latest progresses in a few frontier issues mostly relevant to free surface/interface in ocean *** include TC(tropical cyclone)induced extreme surface wave,sloshing of LNG(liquefied natural gas),cavitation/bubble dynamics and VIM(vortex-induced motion)and VIV(vortex-induced vibration).In addition to general description,we mainly focus on the recent advances and challenging aspects of above-mentioned *** by the achievements in the previous 70 years,mankind starts a new round of ocean exploration ***,we can find obvious trends:the realm of ocean engineering is expanding from sea surface to deep sea,from low and middle latitude to polar region and from fossil to renewable energy in near future.

关键词： tropical cyclone wind wave sloshing cavitation bubble vortex-induced vibration

Nanotechnology-based combinational strategies toward the regulation of myofibroblasts and diseased microenvironment in liver fibrosis and hepatic carcinoma

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Nano Research 2023年第12期16卷 13042-13055页

作者： Fenfen Li Ying Zhao Guangjun nie School of Pharmaceutical Sciences Zhengzhou UniversityZhengzhou 450001China CAS Center for Excellence in Nanoscience National Center for Nanoscience and TechnologyBeijing 101408China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China GBA National Institute for Nanotechnology Innovation Guangzhou 510530China

Liver fibrosis and hepatic carcinoma(HCC)pose a huge challenge worldwide due to the lack of effective treatment options for end-stage liver *** to their functions and roles,hepatic myofibroblasts mainly include nontumoral fibroblasts(mainly activated hepatic stellate cells(HSCs)),which are involved in the wound-healing process of liver fibrosis,and cancer-associated fibroblasts(CAFs)in hepatic *** play a significant role in regulating extracellular matrix(ECM)deposition in progressive liver *** can be derived from activated HSCs and differentiate into ECM-producing ***,growing evidence shows that CAFs are the primary regulators of the HCC microenvironment,releasing growth factors and cytokines and suppressing the antitumor immune *** therapeutic strategies show reduced drug resistance and side ***-based combined strategies aim to improve the delivery efficiency of various therapeutic agents with reduced toxicity via multiple *** this review,we will discuss recent developments in combinational strategies based on nanotechnology that regulate myofibroblasts and the diseased microenvironment for liver fibrosis and HCC *** will also identify the major challenges that the field is facing and offer some insights for future drug discovery.

关键词： fibroblasts liver fibrosis hepatic carcinoma nanotechnology

Dynamic quasi-continuum model for plate-type nano-materials and analysis of fundamental frequency

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Applied Mathematics and Mechanics(English Edition) 2021年第1期42卷 85-94页

作者： Chunxiao XIA Wenlong XU Guohua nie School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

A dynamic quasi-continuum model is presented to analyze free vibration of plate-type cubic crystal *** to the Hamilton principle,fundamental governing equations in terms of displacement components and angles of rotations are *** an application of the model,the cylindrical bending deformation of the structure fixed at two ends is analyzed,and a theoretical formula evaluating the fundamental frequency is obtained by using Galerkin's ***,the solution for the classical continuous plate model is also derived,and the size-dependent elastic modulus and Poisson's ratio are taken in *** frequencies corresponding to different atomic layers are numerically presented for the plate-type NaC l ***,a molecular dynamics(MD)simulation is conducted with the code *** comparison shows that the present quasi-continuum model is valid,and it may be used as an alternative model,which reflects scale effects in analyzing dynamic behaviors of such plate-type nano-materials.

关键词： plate-type nano-material quasi-continuum model size-dependent fundamental frequency theoretical solution molecular dynamics(MD)simulation

Shear behaviours of cohesionless mixed soils using the DEM:The influence of coarse particle shape

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Particuology 2021年第2期19卷 151-165页

作者： Yangui Zhu Jian Gong Zhihong nie School of Civil Engineering Central South UniversityChangsha 410075China

The coarse particles in mixed soils can be cobbles or gravels,with the main difference being their roundness(an indicator describing particle shape characteristics at an intermediate scale).The influence of coarse particle shape(i.e.,roundness)on the macroscopic and microscopic shear behaviours of cohesionless mixed soils with various fines contents(FCs)was investigated via the discrete element method in this *** shapes of coarse particles were formed using the rotation-invariant spherical harmonic method proposed by previous *** equation was proposed to predict the initial void ratios of samples in this study.A decrease in the roundness of coarse particles can increase the peak friction angle(FC≤40%)and critical friction angle(FC≤30%).As the roundness of coarse particles decreases,the peak dilatancy angle initially increases and then decreases(FC≤20%).Furthermore,it was found that the roundness of coarse particles hardly affects the classification of cohesionless mixed soils,as determined by probing the percentage contributions of coarse-coarse,coarse-fine,and fine-fine *** cohesionless mixed soils change from an underfilled structure to an interactive-underfilled structure at the critical state,the main forms of coarse-coarse contacts were ***,the force-fabric anisotropy mechanisms of the influences of the roundness and rolling resistance coefficient of coarse particles on the shear strengths of cohesionless mixed soils were found to be different.

关键词： Cohesionless mixed soils Particle shape Roundness Shear behaviours Discrete element method

Force measurement using strain-gauge balance in shock tunnel based on deep learning

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Chinese Journal of Aeronautics 2023年第8期36卷 43-53页

作者： Shaojun nie Yunpeng WANG Zonglin JIANG State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of ScienceBeijing 100049China

When a force test is conducted in a shock tunnel,vibration of the Force Measurement System(FMS)is excited under the strong flow impact,and it cannot be attenuated rapidly within the extremely short test duration of milliseconds *** output signal of the force balance is coupled with the aerodynamic force and the inertial *** interference can result in inaccurate force measurements,which can negatively impact the accuracy of the test *** eliminate inertial vibration interference from the output signal,proposed here is a dynamic calibration modeling method for an FMS based on deep *** signal is processed using an intelligent Recurrent Neural Network(RNN)model in the time domain and an intelligent Convolutional Neural Network(CNN)model in the frequency *** processed with the intelligent models show that the inertial vibration characteristics of the FMS can be identified efficiently and its main frequency is about 380 *** processed by the intelligent models,the inertial vibration is mostly eliminated from the output ***,the data processing results are subjected to error *** relative error of each component is about 1%,which verifies that the modeling method based on deep learning has considerable engineering application value in data processing for pulse-type strain-gauge ***,the proposed dynamic calibration modeling method has the potential to improve the accuracy and reliability of force measurements in shock tunnel tests,which could have significant implications for the field of aerospace engineering.

关键词： Convolutional neural net-works Deep learning Frequency domain analysis Forcemeasurement Time domain analysis Recurrent neural networks