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Regular Submanifolds in Conformal Space Q_p^n

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Chinese Annals of Mathematics,Series B 2012年第5期33卷 695-714页

作者： Changxiong nie Chuanxi WU Faculty of Mathematics and Computer Sciences -Hubei University Wuhan 430062 China. E-maih chxnie~*** Institute of Mathematics Sciences Hubei University Wuhan 430062 China. E-maih cxwu@***

The authors study the regular submanifolds in the conformal space Qp^n and introduce the submanifold theory in the conformal space Qp^n. The first variation formula of the Willmore volume functional of pseudo-Riemannian submanifolds in the conformal space Qp^n is given. Finally, the conformal isotropic submanifolds in the conformal space

关键词： Conformal space Conformal invariants Willmore submanifolds Conformal isotropic

Swimming velocity of spherical squirmers in a square tube at finite fluid inertia

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1481-1498页

作者： Tongxiao JIANG Deming nie Jianzhong LIN Institute of Fluid Mechanics China Jiliang UniversityHangzhou 310008China Key Laboratory of Impact and Safety Engineering(Ningbo University) Ministry of EducationNingbo 315211China Institute of Fluid Engineering Zhejiang UniversityHangzhou 310027China

The three-dimensional lattice Boltzmann method(LBM)is used to simulate the motion of a spherical squirmer in a square tube,and the steady motion velocity of a squirmer with different Reynolds numbers(Re,ranging from 0.1 to 2)and swimming types is investigated and analyzed to better understand the swimming characteristics of microorganisms in different ***,as the Reynolds number increases,the effect of the inertial forces becomes significant,disrupting the squirmer's ability to maintain its theoretical ***,as the Reynolds number increases,the structure of the flow field around the squirmer changes,affecting its velocity of ***,the swimming velocity of the squirmer exhibits a quadratic relationship with the type of swimming and the Reynolds ***,the narrow tube exerts a significant inhibitory effect on the squirmer *** addition,although chirality does not directly affect the swimming velocity of the squirmer,it can indirectly affect the velocity by changing its motion mode.

关键词： spherical squirmer swimming characteristics swimming velocity fow structure

Recent advances in small-scale hydrogel-based robots for adaptive biomedical applications

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Nano Research 2024年第2期17卷 649-662页

作者： Mingzhe nie Qilong Zhao Xuemin Du Institute of Biomedical&Health Engineering Shenzhen Institute of Advanced Technology(SIAT)Chinese Academy of Sciences(CAS)Shenzhen 518055China

Small-scale robots,ranging in size from micrometers to centimeters,have gained significant attention in the biomedical ***,conventional small-scale robots made of rigid materials encounter challenges in adapting themselves to the soft tissues and complicated environments of human *** to the rigid counterpart,small-scale hydrogel-based robots hold great promises due to their tissue-like low modulus,outstanding biocompatibility and accessible stimuli-responsive *** attributes offer small-scale hydrogel-based robots with multimodal locomotion and reinforced functions,further enhancing the adaptability in manipulation and tasks execution for various biomedical *** this review,we present recent advances in small-scale hydrogel-based *** first summarize the design principles of small-scale hydrogel-based robots including materials,fabrication techniques and manipulation strategies,then highlighting their upgraded functions and adaptive biomedical ***,we discuss existing challenges and future perspectives for small-scale hydrogel-based robots.

关键词： small-scale robot hydrogel locomotion multi-function adaptability

Collectively induced transparency and absorption in waveguide quantum electrodynamics with Bragg atom arrays

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Communications in Theoretical Physics 2024年第8期76卷 19-28页

作者： Haolei Cheng Wei nie Center for Joint Quantum Studies and Department of Physics School of ScienceTianjin UniversityTianjin 300350China Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Tianjin UniversityTianjin 300350China

Collective quantum states, such as subradiant and superradiant states, are useful for controlling optical responses in many-body quantum systems. In this work, we study novel collective quantum phenomena in waveguide-coupled Bragg atom arrays with inhomogeneous *** atoms without free-space dissipation, collectively induced transparency is produced by destructive quantum interference between subradiant and superradiant states. In a large Bragg atom array, multi-frequency photon transparency can be obtained by considering atoms with different frequencies. Interestingly, we find collectively induced absorption(CIA) by studying the influence of free-space dissipation on photon transport. Tunable atomic frequencies nontrivially modify decay rates of subradiant states. When the decay rate of a subradiant state equals to the free-space dissipation, photon absorption can reach a limit at a certain frequency. In other words, photon absorption is enhanced with low free-space dissipation, distinct from previous photon detection schemes. We also show multi-frequency CIA by properly adjusting atomic frequencies. Our work presents a way to manipulate collective quantum states and exotic optical properties in waveguide quantum electrodynamics(QED) systems.

关键词： waveguide quantum electrodynamics collective quantum states photon absorption Bragg atom array

Vector Dominance with Threshold Searchable Encryption (VDTSE) for the Internet of Things

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Computers, Materials & Continua 2024年第6期79卷 4763-4779页

作者： Jingjing nie Zhenhua Chen College of Safety Science and Engineering Xi’an University of Science and TechnologyXi’an710054China College of Computer Science and Technology Xi’an University of Science and TechnologyXi’an710054China

The Internet of Medical Things(IoMT)is an application of the Internet of Things(IoT)in the medical *** is a cutting-edge technique that connects medical sensors and their applications to healthcare systems,which is essential in smart ***,Personal Health Records(PHRs)are normally kept in public cloud servers controlled by IoMT service providers,so privacy and security incidents may be ***,Searchable Encryption(SE),which can be used to execute queries on encrypted data,can address the issue ***,most existing SE schemes cannot solve the vector dominance threshold *** response to this,we present a SE scheme called Vector Dominance with Threshold Searchable Encryption(VDTSE)in this *** use a Lagrangian polynomial technique and convert the vector dominance threshold problem into a constraint that the number of two equal-length vectors’corresponding bits excluding wildcards is not less than a threshold ***,we solve the problem using the proposed technique modified in Hidden Vector Encryption(HVE).This technique makes the trapdoor size linear to the number of attributes and thus much smaller than that of other similar SE schemes.A rigorous experimental analysis of a specific application for privacy-preserving diabetes demonstrates the feasibility of the proposed VDTSE scheme.

关键词： Internet of Things(IoT) Internet of Medical Things(IoMT) vector dominance with threshold searchable encryption(VDTSE) threshold comparison electronic healthcare

COUPLING DISTINCT AND CONTINUOUS MEDIUM MODEL FOR FLOW ANALYSIS IN A FRACTURED ROCK MASS AND ITS APPLICATION

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Journal of Hydrodynamics 1998年第2期10卷 94-104页

作者： Wang, Hongtao nie, Yongfeng Tsinghua Univ Beijing China

Method for analyzing a three-dimensional ground water flow in fractured rock mass was presented, in which flow in dominant fracture system was described by a distinct medium model, while flow in network fracture system plus rock matrices was described by a continuous medium model. Two models were coupled by using hydraulic head and flux. The method can be applied to a large sized domain. In addition, a method by using network geometry data to calculate its equivalent porous permeability was also discussed. The results of a theoretical calculation show that the coupled method can effectively analyze ground water flow in fractured rock mass.

关键词： Fracture Mathematical models Mechanical permeability Porous materials Rocks

AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES

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Acta Mechanica Solida Sinica 2007年第4期20卷 289-295页

作者： Guojun nie Zheng Zhong School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China

Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical nu- merical method is with great advantage in the computational efficiency. Moreover, study on ax- isymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials.

关键词： two-directional functionally graded materials circular and annular plates axisym-metric bending semi-analytical numerical method integrated design

Schwarz lemma from a Kähler manifold into a complex Finsler manifold

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Science China Mathematics 2022年第8期65卷 1661-1678页

作者： Jun nie Chunping Zhong School of Mathematical Sciences Xiamen UniversityXiamen 361005China

Suppose that M is a complete Kähler manifold such that its holomorphic sectional curvature is bounded from below by a constant and its radial sectional curvature is also bounded from *** that N is a strongly pseudoconvex complex Finsler manifold such that its holomorphic sectional curvature is bounded from above by a negative *** this paper,we establish a Schwarz lemma for holomorphic mappings f from M into *** applications,we obtain a Liouville type rigidity result for holomorphic mappings f from M into N,as well as a rigidity theorem for bimeromorphic mappings from a compact complex manifold into a compact complex Finsler manifold.

关键词： Schwarz lemma Kähler manifold complex Finsler manifold holomorphic sectional curvature

Matched Volterra reduced-order model for an airfoil undergoing periodic translation

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Chinese Journal of Aeronautics 2024年第1期37卷 19-23页

作者： Lianrui nie Ziniu WU Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

This paper is devoted to application of the Reduced-Order Model(ROM)based on Volterra series to prediction of lift and drag forces due to airfoil periodic translation in transonic flow *** there is large amplitude oscillation of the relative Mach number,as appeared in helicopter rotor movement in forward flight,the conventional Volterra ROM is found to be *** cover such applications,a matched Volterra ROM,inspired from previous multistep nonlinear indicial response method based on Duhamel integration,is thus considered,in which the step motions are defined inside a number of equal intervals with both positive and negative step motions to match the airfoil forward and backward movement,and the kernel functions are constructed independently at each *** shows that,at least for the translation movement considered,this matched Volterra ROM greatly improves the accuracy of ***,the matched Volterra ROM,with the total number of step motions and thus the computational cost close to those of the conventional Volterra ROM method,has the additional advantage that the same set of kernels can match various translation motions with different starting conditions so the kernels can be predesigned without knowing the specific motion of airfoil.

关键词： Airfoil periodic translation Lift and drag Reduced-order model Transonic flow Unsteady flow