期刊文献+
共找到3,531篇文章
< 1 2 177 >
每页显示 20 50 100
Landscape Planning and Design of Folk Culture Block Based on Theory of Three Elements of Landscape
1
作者 吴忠军 胡林波 梁莉清 《Journal of Landscape Research》 2010年第9期24-28,共5页
This paper firstly defined the concept of folk culture block,and then analyzed the significance and planning principle of landscape design in folk culture block,and at last expounded landscape planning and design of f... This paper firstly defined the concept of folk culture block,and then analyzed the significance and planning principle of landscape design in folk culture block,and at last expounded landscape planning and design of folk culture block based on theory of three elements of landscape. 展开更多
关键词 theory of THREE elements of LANDSCAPE FOLK culture BLOCK LANDSCAPE planning and design
下载PDF
Some New Results from the Electron Theory on the Elastical of Alkahoe Earth Metals and Rare Earth Elements
2
作者 崔秀山 邢胜娣 《Journal of Beijing Institute of Technology》 EI CAS 1994年第1期31+26-32,共8页
With the introduction of Poisson's ratio in the expression of Young's modulus,nearly all the theoretical values of the various elastic moduli for the alkaline earth metals and rare earth elements can be greatl... With the introduction of Poisson's ratio in the expression of Young's modulus,nearly all the theoretical values of the various elastic moduli for the alkaline earth metals and rare earth elements can be greatly refined, with the single exception of the theoreticalvalue of Young's modulus for Pr which is slightly increased This points to the validityof the new theory, that the bulk modulus is independent of the Poisson's ratio, and further that the valency electron structures of solids as determined by Yu's theory are correct. 展开更多
关键词 alkaline earth metals rare earth elements/electron theory of elasticity
下载PDF
Kinematics and Dynamics of Deployable Structures with Scissor-Like-Elements Based on Screw Theory 被引量:20
3
作者 SUN Yuantao WANG Sanmin +1 位作者 MILLS James K ZHI Changjian 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2014年第4期655-662,共8页
Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dyna... Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element(SLE). First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory. 展开更多
关键词 scissor-like-element screw theory KINEMATICS DYNAMICS the principle of virtual work
下载PDF
The Dynamic System Theory of Legal Protection for Personal Information Rights Infringement
4
作者 莫杨燊 NI Weis 《The Journal of Human Rights》 2024年第1期143-172,共30页
The advent of the big data era has presented unprecedented challenges to remedies for personal information infringement in areas such as damage assessment,proof of causation,determination of illegality,fault assessmen... The advent of the big data era has presented unprecedented challenges to remedies for personal information infringement in areas such as damage assessment,proof of causation,determination of illegality,fault assessment,and liability.Traditional tort law is unable to provide a robust response for these challenges,which severely hinders human rights protection in the digital society.The dynamic system theory represents a third path between fixed constitutive elements and general clauses.It both overcomes the rigidity of the“allor-nothing”legal effect evaluation mechanism of the“element-effect”model and avoids the uncertainty of the general clause model.It can effectively enhance the flexibility of the legal system in responding to social changes.In light of this,it is necessary to construct a dynamic foundational evaluation framework for personal information infringement under the guidance of the dynamic system theory.By relying on the dynamic interplay effect of various foundational evaluation elements,this framework can achieve a flexible evaluation of the constitutive elements of liability and the legal effects of liability for personal information infringement.Through this approach,the crisis of personal information infringement in the era of big data can be mitigated,and the realization of personal information rights as digital human rights can be promoted. 展开更多
关键词 personal information digital human rights dynamic system theory constitutive elements of torts LIABILITY
下载PDF
Skopos theory and translating strategies of cultural elements in tourism texts
5
作者 MA Jing REN Su-zhen 《Sino-US English Teaching》 2008年第9期34-37,共4页
Tourism texts (shortened as TT) have become a principal means of promoting tourism in China. Cultural elements are abundant in those texts. Therefore, the proper understanding and rendering of such messages is the k... Tourism texts (shortened as TT) have become a principal means of promoting tourism in China. Cultural elements are abundant in those texts. Therefore, the proper understanding and rendering of such messages is the key to the quality of TT translation. Based on Skopos theory the paper focuses on the translating strategies of TT cultural elements. 展开更多
关键词 tourism texts (TT) cultural elements Skopos theory translating strategies
下载PDF
Bending of small-scale Timoshenko beams based on the integral/differential nonlocal-micropolar elasticity theory: a finite element approach 被引量:3
6
作者 M. FARAJI-OSKOUIE A. NOROUZZADEH +1 位作者 R. ANSARI H. ROUHI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第6期767-782,共16页
A novel size-dependent model is developed herein to study the bending behavior of beam-type micro/nano-structures considering combined effects of nonlocality and micro-rotational degrees of freedom. To accomplish this... A novel size-dependent model is developed herein to study the bending behavior of beam-type micro/nano-structures considering combined effects of nonlocality and micro-rotational degrees of freedom. To accomplish this aim, the micropolar theory is combined with the nonlocal elasticity. To consider the nonlocality, both integral (original) and differential formulations of Eringen’s nonlocal theory are considered. The beams are considered to be Timoshenko-type, and the governing equations are derived in the variational form through Hamilton’s principle. The relations are written in an appropriate matrix-vector representation that can be readily utilized in numerical approaches. A finite element (FE) approach is also proposed for the solution procedure. Parametric studies are conducted to show the simultaneous nonlocal and micropolar effects on the bending response of small-scale beams under different boundary conditions. 展开更多
关键词 INTEGRAL MODEL of NONLOCAL ELASTICITY DIFFERENTIAL MODEL of NONLOCAL ELASTICITY MICROPOLAR theory finite element (FE) analysis Timoshenko nano-beam
下载PDF
A new higher-order shear deformation theory and refined beam element of composite laminates 被引量:3
7
作者 WanjiChen ZhenWu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2005年第1期65-69,共5页
A new higher-order shear deformation theory based on global-local superposition technique is developed. The theory satisfies the free surface conditions and the geometric and stress continuity conditions at interfaces... A new higher-order shear deformation theory based on global-local superposition technique is developed. The theory satisfies the free surface conditions and the geometric and stress continuity conditions at interfaces. The global displacement components are of the Reddy theory and local components are of the internal first to third-order terms in each layer. A two-node beam element based on this theory is proposed. The solutions are compared with 3D-elasticity solutions. Numerical results show that present beam element has higher computational efficiency and higher accuracy. 展开更多
关键词 Laminated composite beam Higher-order shear deformation theory Refined beam element
下载PDF
Conversion between solid and beam element solutions of finite element method based on meta-modeling theory:development and application to a ramp tunnel structure 被引量:1
8
作者 JASC Jayasinghe M. Hori +2 位作者 MR Riaz MLL Wijerathne T Ichimura 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第2期297-309,共13页
In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. ... In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. The proposed method is rigorous and efficient compared to a typical conversion method which merely computes surface integration of solid element nodal stresses to obtain cross-sectional forces. The meta-modeling theory ensures the rigorousness of proposed method by defining a proper distance between beam element and solid element solutions in a function space of continuum mechanics. Results of numerical verification test that is conducted with a simple cantilever beam are used to find the proper distance function for this conversion. Time history analysis of the main tunnel structure of a real ramp tunnel is considered as a numerical example for the proposed conversion method. It is shown that cross-sectional forces are readily computed for solid element solution of the main tunnel structure when it is converted to a beam element solution using the proposed method. Further, envelopes of resultant forces which are of primary importance for the purpose of design, are developed for a given ground motion at the end. 展开更多
关键词 meta-modeling theory finite element method solid and beam element models continuum mechanics structural mechanics
下载PDF
Simulation of bulk metal forming processes using one-step finite element approach based on deformation theory of plasticity 被引量:2
9
作者 王鹏 董湘怀 傅立军 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第2期276-282,共7页
The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/stra... The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method. 展开更多
关键词 bulk metal forming plastic deformation theory finite element method one-step forward simulation rigid-plastic materials
下载PDF
Calculation of the Coupling Coefficient of Twin-Core Fiber Based on the Supermode Theory with Finite Element Method 被引量:1
10
作者 Tianhao Zhao Wenhua Ren +1 位作者 Tingya Yin Fan Wang 《Optics and Photonics Journal》 2021年第8期402-411,共10页
<div style="text-align:justify;"> Currently, coupled mode theory (CMT) is widely used for calculating the coupling coefficient of twin-core fibers (TCFs) that are used in a broad range of important app... <div style="text-align:justify;"> Currently, coupled mode theory (CMT) is widely used for calculating the coupling coefficient of twin-core fibers (TCFs) that are used in a broad range of important applications. This approach is highly accurate for scenarios with weak coupling between the cores but shows significant errors in the strong coupling scenarios, necessitating the use of a more accurate method for coupling coefficient calculations. Therefore, in this work, we calculate the coupling coefficients of TCFs using the supermode theory with finite element method (FEM) that has higher accuracy than CMT, particularly for the strong coupling TCF. To investigate the origin of the differences between the results obtained by these two methods, the modal field distributions of the supermodes of TCF are simulated and analyzed in detail. </div> 展开更多
关键词 Coupling Coefficient Twin-Core Fiber Supermode theory Finite element Method Coupled Mode theory
下载PDF
Perturbation Theory Combined with Boundary Element Method for Analysis of Gear Contact Problems
11
作者 罗立风 常山 陈谌闻 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1997年第3期48-52,共5页
This paper combines the perturbation theory with the boundary element methodfor contact problems of three-dimensional elasticity mechanism to analyse the effect oferrors on the shape of the contact area and pressure d... This paper combines the perturbation theory with the boundary element methodfor contact problems of three-dimensional elasticity mechanism to analyse the effect oferrors on the shape of the contact area and pressure distribution in gear drive through theperturbation of a cubic order geometry,there by greatly bringing down both computationwork volume and cost and providing a powerful tool for engineering study on the effectof errors on structural strength. 展开更多
关键词 PERTURBATION theory BOUNDARY element method error GEAR
下载PDF
Quadrilateral 2D linked-interpolation finite elements for micropolar continuum
12
作者 Sara Grbcic Gordan Jelenic Dragan Ribarc? 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2019年第5期1001-1020,共20页
Quadrilateral finite elements for linear micropolar continuum theory are developed using linked interpolation.In order to satisfy convergence criteria,the newly presented finite elements are modified using the Petrov-... Quadrilateral finite elements for linear micropolar continuum theory are developed using linked interpolation.In order to satisfy convergence criteria,the newly presented finite elements are modified using the Petrov-Galerkin method in which different interpolation is used for the test and trial functions.The elements are tested through four numerical examples consisting of a set of patch tests,a cantilever beam in pure bending and a stress concentration problem and compared with the analytical solution and quadrilateral micropolar finite elements with standard Lagrangian interpolation.In the higher-order patch test,the performance of the first-order element is significantly improved.However,since the problems analysed are already describable with quadratic polynomials,the enhancement due to linked interpolation for higher-order elements could not be highlighted.All the presented elements also faithfully reproduce the micropolar effects in the stress concentration analysis,but the enhancement here is negligible with respect to standard Lagrangian elements,since the higher-order polynomials in this example are not needed. 展开更多
关键词 MICROPOLAR theory FINITE element method Linked INTERPOLATION QUADRILATERAL elements
下载PDF
Finite element implementation of poroelasticity theory for swelling dynamics of hydrogels
13
作者 Meie Li Chao Jin Jinxiong Zhou 《Theoretical & Applied Mechanics Letters》 CAS 2013年第5期42-44,共3页
Abstract Hydrogel can swell to many times of its dry volume, resulting in large deformation which is vital for its function. The swelling process is regulated by many physical and chemical mechanisms, and can, to some... Abstract Hydrogel can swell to many times of its dry volume, resulting in large deformation which is vital for its function. The swelling process is regulated by many physical and chemical mechanisms, and can, to some extent, be fairly described by the poroelasticity theory. Implementation of the poroelastieity theory in the framework of finite element method would aid the design and optimization of hydrogel-based soft devices. Choosing chemical potential and displacement as two field variables, we present the implementation of poroelastieity tailored for hydrogel swelling dynamics, detail the normalization of physical parameters and the treatment of boundary conditions. Several examples are presented to demonstrate the feasibility and correctness of the proposed strategy. 展开更多
关键词 finite element poroelasticity theory NORMALIZATION boundary conditions
下载PDF
18-DOF Triangular Quasi-Conforming Element for Couple Stress Theory
14
作者 Xiangkui Zhang ChangshengWang Ping Hu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2016年第6期473-492,共20页
The basic idea of quasi-conforming method is that the strain-dis-placement equations are weakened as well as the equilibrium equations.In this paper,an 18-DOF triangular element for couple stress theory is proposed wi... The basic idea of quasi-conforming method is that the strain-dis-placement equations are weakened as well as the equilibrium equations.In this paper,an 18-DOF triangular element for couple stress theory is proposed within the framework of quasi-conforming technique.The formulation starts from truncated Taylor expansion of strains and appropriate interpolation functions are chosen to calculate strain integration.This element satisfies C0 continuity with second order accuracy and weak C1 continuity simultaneously.Numerical examples demonstrate that the proposed model can pass the C0??1 patch test and has high accuracy.The element does not exhibit extra zero energy modes and can capture the scale effects of microstructure. 展开更多
关键词 COUPLE stress theory TRIANGULAR quasi-conforming element enhanced PATCH test SCALE effect
下载PDF
Vibration analysis of two-dimensional structures using micropolar elements
15
作者 M.KOHANSAL-VAJARGAH R.ANSARI +1 位作者 M.FARAJI-OSKOUIE M.BAZDID-VAHDATI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第7期999-1012,共14页
Based on the micropolar theory(MPT),a two-dimensional(2 D)element is proposed to describe the free vibration response of structures.In the context of the MPT,a 2 D formulation is developed within the ABAQUS finite ele... Based on the micropolar theory(MPT),a two-dimensional(2 D)element is proposed to describe the free vibration response of structures.In the context of the MPT,a 2 D formulation is developed within the ABAQUS finite element software.The user-defined element(UEL)subroutine is used to implement a micropolar element.The micropolar effects on the vibration behavior of 2 D structures with arbitrary shapes are studied.The effect of micro-inertia becomes dominant,and by considering the micropolar effects,the frequencies decrease.Also,there is a considerable discrepancy between the predicted micropolar and classical frequencies at small scales,and this difference decreases when the side length-to-length scale ratio becomes large. 展开更多
关键词 finite element method(FEM) quadrilateral element micropolar theory(MPT) user-defined element(UEL)subroutine free vibration
下载PDF
A New Rectangular Finite Element Formulation Based on Higher Order Displacement Theory for Thick and Thin Composite and Sandwich Plates
16
作者 Sanjib Goswami Wilfried Becker 《World Journal of Mechanics》 2013年第3期194-201,共8页
A new displacement based higher order element has been formulated that is ideally suitable for shear deformable composite and sandwich plates. Suitable functions for displacements and rotations for each node have been... A new displacement based higher order element has been formulated that is ideally suitable for shear deformable composite and sandwich plates. Suitable functions for displacements and rotations for each node have been selected so that the element shows rapid convergence, an excellent response against transverse shear loading and requires no shear correction factors. It is completely lock-free and behaves extremely well for thin to thick plates. To make the element rapidly convergent and to capture warping effects for composites, higher order displacement terms in the displacement kinematics have been considered for each node. The element has eleven degrees of freedom per node. Shear deformation has also been considered in the formulation by taking into account shear strains ( rxz and ryz) as nodal unknowns. The element is very simple to formulate and could be coded up in research software. A small Fortran code has been developed to implement the element and various examples of isotropic and composite plates have been analyzed to show the effectiveness of the element. 展开更多
关键词 Finite element DISPLACEMENT Approach Plate Bending COMPOSITE Shear Deformation Higher Order theory LOCK-FREE
下载PDF
The Influence of Alkaline Earth Elements on Electronic Properties ofα-Si3N4 via DFT Calculation
17
作者 ZHANG Jianwen HUANG Zhifeng +3 位作者 YIN Ziqian LI Meijuan CHEN Fei SHEN Qiang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2020年第5期863-871,共9页
We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alka... We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alkaline earth metal elements results in structural expansion when they were doped into theα-Si3N4 lattice.Formation energies of the doped structures indicate that dopants prefer to occupy the interstitial site under the nitrogen-deficient environment,while substitute Si under the nitrogen-rich environment,which provides a guide to synthesizingα-Si3N4 with different doping types by controlling nitrogen conditions.For electronic structures,energy levels of the dopants appear in the bottom of the conduction band or the top of the valence band or the forbidden band,which reduces the bandgap ofα-Si3N4. 展开更多
关键词 FIRST-PRINCIPLES density functional theory calculations alkaline earth elements dopedα-Si3N4 photoluminescence material crystal structure electronic structure
下载PDF
THE RATIONALISM THEORY AND ITS FINITE ELEMENT ANALYSIS METHOD OF SHELL STRUCTURES
18
作者 李龙元 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1990年第4期395-402,共8页
In this paper, a kind of rationalism theory of shell is established which is of different mechanic characters in tension and in compression, and the finite element numerical analysis method is also described.
关键词 THE RATIONALISM theory AND ITS FINITE element ANALYSIS METHOD OF SHELL STRUCTURES THAN
下载PDF
The Dao of Mathematical Creativity,Symmetry Theories,and Yin-Yang Philosophy With Their Classroom Applications
19
作者 WANG Tongjun 《Sino-US English Teaching》 2020年第10期306-313,共8页
This paper introduces creativity,one of the significant features in maths.The creative mathematical beauty of symmetry and asymmetry are worth investigating in the practicing of Taichi.Symmetrical variances make the r... This paper introduces creativity,one of the significant features in maths.The creative mathematical beauty of symmetry and asymmetry are worth investigating in the practicing of Taichi.Symmetrical variances make the real world.Symmetry can be regarded as a kind of mirroring,like the line symmetry,the mirror image of the other parts,or rotational symmetry.Such characteristics can be vividly demonstrated in the traditional Chinese philosophical yin-yang theory(YY).The accompanying of male and female reveals the friendly cooperative relationship.YY reflects the counterparts of vacancy and firm,inhale and exhale,noun and verb,theory and practice,light and heavy,slow and fast,the pace,the sound effect in the classroom.Such an analysis is undergone about yin and yang in Yi School and Dao De Ching(DDC).Furthermore,there are detailed arguments of the symmetric nature of every verse of DDC,revealing the cultural value of the language.Their applications in the class admit the recognition under the new liberal arts project by China’s Ministry of Education.Yet,the integration of research and teaching is required to go further. 展开更多
关键词 mathematical creativity symmetry and asymmetry yin-yang theory(YY) Dao De Ching(DDC)
下载PDF
The Application of Ecological Elements of Digital Technology in Construction Industry
20
作者 Jie Sun 《Open Journal of Civil Engineering》 2021年第1期14-27,共14页
The application of digital technology in the field of construction is still in its infancy, and the existing concrete framework of digital technology application in the construction industry and the study of applied e... The application of digital technology in the field of construction is still in its infancy, and the existing concrete framework of digital technology application in the construction industry and the study of applied ecological elements are not enough. The ecological elements of digital technology application in the construction industry are important factors that promote the healthy op</span><span style="font-family:Verdana;">eration of the entire digital technology application ecosystem. </span><span style="font-family:Verdana;">Using grounded theory, we compiled the data of 33 researchers who participated in </span><span style="font-family:Verdana;">semi-structured interviews, and obtained 4 main categories and 9</span><span style="font-family:Verdana;"> sub-categories of ecological elements of digital technology application in the construction industry. Among them, the digital technology application mechanism is the core category of ecological application elements. We also used the Bass model to analyze the application trend of digital technology in the construction industry. </span><span style="font-family:Verdana;">In 2040, the number of construction companies applying digital</span><span style="font-family:Verdana;"> technology will reach 98.66% of the maximum market potential. 展开更多
关键词 Digital Technology in Construction Industry Ecological elements Technology Diffusion Grounded theory Bass Model
下载PDF
上一页 1 2 177 下一页 到第
使用帮助 返回顶部