New developments have been made on the applications of the differential quadrature(DQ)method to analysis of structural problems recently.The method is used to obtain solutions of large deflections, membrane and bendin...New developments have been made on the applications of the differential quadrature(DQ)method to analysis of structural problems recently.The method is used to obtain solutions of large deflections, membrane and bending stresses of circular plates with movable and immovable edges under uniform pressures or a central point load.The shortcomings existing in the earlier analysis by the DQ method have been overcome by a new approach in applying the boundary conditions. The accuracy and the efficiency of the newly developed method for solving nonlinear problems are demonstrated.展开更多
The static behavior of piezoelectric circular spherical shallow shells under both electrical and mechanical loads is studied by using the differential quadrature element method (DQEM). Geometrical nonlinearity effect ...The static behavior of piezoelectric circular spherical shallow shells under both electrical and mechanical loads is studied by using the differential quadrature element method (DQEM). Geometrical nonlinearity effect is considered. Detailed formulations and procedures are given for the first time. Several examples are analyzed and accurate results are obtained by the DQEM. Based on the results in this paper, one may conclude that the DQEM is a useful tool for obtaining solutions of structural elements. It can be seen that the shell shape may be theore tically controlled and snap through may occur when the applied voltage reaches a critical value even without mechanical load for certain geometric configurations.展开更多
探索和完善更合乎逻辑的分离设计体系,以中基线拉伸补偿为目的,提出基于独立非线性参数异位化性能的直接设计方法。使用直接基于性能的设计方法和传统的微调计数方法设计和分析真实工程,比较不同分离结构中数值单环法的差异,研究不同性...探索和完善更合乎逻辑的分离设计体系,以中基线拉伸补偿为目的,提出基于独立非线性参数异位化性能的直接设计方法。使用直接基于性能的设计方法和传统的微调计数方法设计和分析真实工程,比较不同分离结构中数值单环法的差异,研究不同性能降低系数下不同设计方法中内力响应和基于性能的直接设计方法的经济效益。结论:FNA方法与直接和球体的内力响应差异小于10%,不同的C函数调整系数对地板加固影响不大,但光束柱组件存在差异。如果值 C 为 0.5,则梁柱的钢含量小于微平系数法,如果 C 值为 0.7,则框架柱的钢含量高于微平系数法。一句话:基于性能的隔离结构的直接设计方法不仅显著降低了母体结构的地板响应,而且通过多种性能补偿因素实现了各种性能设计目标。笔者结合身多年设计工作经验,本次主要针对基于性能的隔震结构直接设计方法展开深入研究,所得文献与同行业人员共享,望对行业的前进起到一定的促进作用。展开更多
The Finite volume backward Euler difference method is established to discuss two-dimensional parabolic integro-differential equations.These results are new for finite volume element methods for parabolic integro-diffe...The Finite volume backward Euler difference method is established to discuss two-dimensional parabolic integro-differential equations.These results are new for finite volume element methods for parabolic integro-differential equations.展开更多
On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rota- tion and small strain established before and from the generalized-a time integration ...On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rota- tion and small strain established before and from the generalized-a time integration algorithm, the energy conserving and de- caying algorithms for corotational formulation nonlinear dynamic response analysis of thin shells are established in this paper. Responses are solved by means of a predictor-corrector procedure. In the case of ignoring the structural damping, the conserv- ing or decaying total energy of structure and the controllable numerical damping for high frequency responses can ensure the numerical stability of the algorithm. The inertial parts are linearly interpolated directly in the fixed global coordinate system by using the element nodal displacement in the global coordinate system for obtaining the constant mass matrix, while the elastic parts adopt the corotational formulation. Hence, the whole formulation obtained in this paper is element independent. Through three typical numerical examples, the performances of the algorithm in this paper were compared with those of the classical Newmak and HHT-a algorithms to indicate that the algorithm in this paper could accurately solve nonlinear dynamic respons- es of thin shells with large displacements and large rotations.展开更多
This paper investigated the nonlinear vibration of functionally graded beams containing an open edge crack based on Timoshenko beam theory.The cracked section is modeled by a massless elastic rotational spring.It is a...This paper investigated the nonlinear vibration of functionally graded beams containing an open edge crack based on Timoshenko beam theory.The cracked section is modeled by a massless elastic rotational spring.It is assumed that material properties follow exponential distributions through the beam thickness.The differential quadrature(DQ) method is employed to discretize the nonlinear governing equations which are then solved by a direct iterative method to obtain the nonlinear vibration frequencies of beams with different boundary conditions.The effects of the material gradient,crack depth and boundary conditions on nonlinear free vibration characteristics of the cracked FGM beams are studied in detail.展开更多
Abstract Magnetic resonance electrical impedance tomography （MREIT, for short） is a new medical imaging technique developed recently to visualize the cross-section conduc- tivity of biologic tissues. A new MREIT ima...Abstract Magnetic resonance electrical impedance tomography （MREIT, for short） is a new medical imaging technique developed recently to visualize the cross-section conduc- tivity of biologic tissues. A new MREIT image reconstruction method called harmonic Bz algorithm was proposed in 2002 with the measurement of Bz that is a single component of an induced magnetic flux density subject to an injection current. The key idea is to solve a nonlinear integral equation by some iteration process. This paper deals with the convergence analysis as well as the error estimate for noisy input data Bz, which is the practical situation for MREIT. By analyzing the iteration process containing the Laplacian operation on the input magnetic field rigorously, the authors give the error estimate for the iterative solution in terms of the noisy level 6 and the regularizing scheme for determining ABz approximately from the noisy input data. The regularizing scheme for computing the Laplacian from noisy input data is proposed with error analysis. Our results provide both the theoretical basis and the implementable scheme for evaluating the reconstruction accuracy using harmonic Bz algorithm with practical measurement data containing noise.展开更多
文摘New developments have been made on the applications of the differential quadrature(DQ)method to analysis of structural problems recently.The method is used to obtain solutions of large deflections, membrane and bending stresses of circular plates with movable and immovable edges under uniform pressures or a central point load.The shortcomings existing in the earlier analysis by the DQ method have been overcome by a new approach in applying the boundary conditions. The accuracy and the efficiency of the newly developed method for solving nonlinear problems are demonstrated.
文摘The static behavior of piezoelectric circular spherical shallow shells under both electrical and mechanical loads is studied by using the differential quadrature element method (DQEM). Geometrical nonlinearity effect is considered. Detailed formulations and procedures are given for the first time. Several examples are analyzed and accurate results are obtained by the DQEM. Based on the results in this paper, one may conclude that the DQEM is a useful tool for obtaining solutions of structural elements. It can be seen that the shell shape may be theore tically controlled and snap through may occur when the applied voltage reaches a critical value even without mechanical load for certain geometric configurations.
文摘探索和完善更合乎逻辑的分离设计体系,以中基线拉伸补偿为目的,提出基于独立非线性参数异位化性能的直接设计方法。使用直接基于性能的设计方法和传统的微调计数方法设计和分析真实工程,比较不同分离结构中数值单环法的差异,研究不同性能降低系数下不同设计方法中内力响应和基于性能的直接设计方法的经济效益。结论:FNA方法与直接和球体的内力响应差异小于10%,不同的C函数调整系数对地板加固影响不大,但光束柱组件存在差异。如果值 C 为 0.5,则梁柱的钢含量小于微平系数法,如果 C 值为 0.7,则框架柱的钢含量高于微平系数法。一句话:基于性能的隔离结构的直接设计方法不仅显著降低了母体结构的地板响应,而且通过多种性能补偿因素实现了各种性能设计目标。笔者结合身多年设计工作经验,本次主要针对基于性能的隔震结构直接设计方法展开深入研究,所得文献与同行业人员共享,望对行业的前进起到一定的促进作用。
基金Supported by the NSF of China(4080502090511009+2 种基金107020506070401560877001)
文摘The Finite volume backward Euler difference method is established to discuss two-dimensional parabolic integro-differential equations.These results are new for finite volume element methods for parabolic integro-differential equations.
基金supported by the National Natural Science Foundation of China (Grant No. 51075208)the Innovation Project for Graduate Students of Jiangsu Province (Grant No. CX07B-162z)the Fund for Innovative and Excellent Doctoral Dissertation of NUAA (Grant No. BCXJ07-01)
文摘On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rota- tion and small strain established before and from the generalized-a time integration algorithm, the energy conserving and de- caying algorithms for corotational formulation nonlinear dynamic response analysis of thin shells are established in this paper. Responses are solved by means of a predictor-corrector procedure. In the case of ignoring the structural damping, the conserv- ing or decaying total energy of structure and the controllable numerical damping for high frequency responses can ensure the numerical stability of the algorithm. The inertial parts are linearly interpolated directly in the fixed global coordinate system by using the element nodal displacement in the global coordinate system for obtaining the constant mass matrix, while the elastic parts adopt the corotational formulation. Hence, the whole formulation obtained in this paper is element independent. Through three typical numerical examples, the performances of the algorithm in this paper were compared with those of the classical Newmak and HHT-a algorithms to indicate that the algorithm in this paper could accurately solve nonlinear dynamic respons- es of thin shells with large displacements and large rotations.
基金supported by the National Natural Science Foundation of China (Grant No. 11002019)Ph.D. Programs Foundation of the Ministry of Education of China (Grant No. 20100009120018)the Fundamental Research Funds for the Central Universities (Grant No. 2009JBM073)
文摘This paper investigated the nonlinear vibration of functionally graded beams containing an open edge crack based on Timoshenko beam theory.The cracked section is modeled by a massless elastic rotational spring.It is assumed that material properties follow exponential distributions through the beam thickness.The differential quadrature(DQ) method is employed to discretize the nonlinear governing equations which are then solved by a direct iterative method to obtain the nonlinear vibration frequencies of beams with different boundary conditions.The effects of the material gradient,crack depth and boundary conditions on nonlinear free vibration characteristics of the cracked FGM beams are studied in detail.
基金supported by the National Natural Science Foundation of China(No.91330109)the Research Found for the Doctoral Program of Higher Education of China(No.20110092110018)
文摘Abstract Magnetic resonance electrical impedance tomography （MREIT, for short） is a new medical imaging technique developed recently to visualize the cross-section conduc- tivity of biologic tissues. A new MREIT image reconstruction method called harmonic Bz algorithm was proposed in 2002 with the measurement of Bz that is a single component of an induced magnetic flux density subject to an injection current. The key idea is to solve a nonlinear integral equation by some iteration process. This paper deals with the convergence analysis as well as the error estimate for noisy input data Bz, which is the practical situation for MREIT. By analyzing the iteration process containing the Laplacian operation on the input magnetic field rigorously, the authors give the error estimate for the iterative solution in terms of the noisy level 6 and the regularizing scheme for determining ABz approximately from the noisy input data. The regularizing scheme for computing the Laplacian from noisy input data is proposed with error analysis. Our results provide both the theoretical basis and the implementable scheme for evaluating the reconstruction accuracy using harmonic Bz algorithm with practical measurement data containing noise.
