bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite‐deformation interface formulation for frictionless contact problems
Authors: Kowalczyk Piotr 
Published: August 2005

AbstractAn interface finite element for non‐linear analysis of frictionless contact problems is presented. A constitutive equation relates stresses in the interface layer to the deformation gradient with respect to an imaginary reference configuration where the layer thickness is constant and finite. The equation of equilibrium is written in the same configuration, while the boundary conditions involve stresses related to an actual reference configuration used in the formulation for the contacting bodies. Finite element discretization is introduced for the layer in order to calculate the unknown field of displacements. Computational examples demonstrate properties of the contact element and its range of applicability in the analysis of large deformation contact problems including relative sliding of curved surfaces.
A BEM formulation of new boundary stress components
Authors: Xiao‐Yan Lei 
Published: August 2005

AbstractThe paper presents boundary integral equation to two‐dimensional elasticity with the stress component σijtitj as one of the boundary values, where ti are direction cosines of the tangent on the boundary. This form of BEM has an advantage in that the stress component σijtitj on the boundary can be calculated directly from the numerical solution. The present formulation for planar problems uses two kernels, one of which is logarithmic singular and the other is 1/r singular. The effectiveness of the approach is also discussed through some test examples.
Numerical viscosities of difference schemes
Authors: Ramshaw John D. 
Published: August 2005

AbstractNumerical viscosities of finite‐difference schemes are usually obtained from truncation‐error analyses based on Taylor series expansions. Here we observe that numerical viscosities can also be obtained very simply and directly from the growth factor ξ in a conventional Fourier stability analysis. A general formula is derived for the numerical viscosity in terms of the first and second derivatives of ξ with respect to the wavenumber k, evaluated at k = 0. A single Fourier analysis therefore suffices to determine both stability limits and numerical viscosities.
Higher‐order numerical methods for third‐order non‐linear boundary value problems
Authors: Tirmizi Ikram A. 
Published: August 2005

AbstractA sixth‐order and a ninth‐order method are developed for the numerical solution of special non‐linear third‐order boundary value problems y‴ = ø(x,y), a< x < b, y(a) = A1, y″(a) = B2 and y(b) = A2. The method arise from a four‐point recurrence relation. Convergence analysis of the sixth‐order method is discussed. The methods are tested on a problem. Modification to these methods are obtained for problems with boundary conditions of the form y(a) = A1, y'(a) = B1 and y(b) = A2.
Further developments towards a new virtual‐pulse time integral methodology for general non‐linear transient thermal analysis
Authors: Tamma K. K. , Chen X. , Sha D. 
Published: August 2005

AbstractNew developments of describing the theoretical basis towards an effective virtual‐pulse (VIP) time integral methodology are proposed for general non‐linear transient heat transfer problems. Primarily to validate the proposed methodology of computation, simple numerical test cases are provided and comparisons are also drawn with the implicit second‐order‐accurate Crank‐Nicolson method. For the models tested, the proposed method has comparable or improved accuracy and stability characteristics. The VIP methodology introduced here for tackling non‐linear thermal problems offers attractive features and is a viable alternative to traditional time‐stepping practices. Efforts are underway to demonstrate the practical applicability to multi‐dimensional thermal analysis.
A new type of B3‐spline interpolation
Authors: van Erp G. M. , Yuen S. W. , Swannell P. 
Published: August 2005

AbstractA new type of B3‐spline interpolation is presented. This new formulation allows the user to introduce interior point and line supports in much the same way as in a conventional finite element formulation. The bandedness and efficiency of the standard B3‐spline interpolation are retained. The new formulation can be incorporated into existing B3‐spline formulations with very little effort. Several examples are presented to demonstrate the versatility of the new approach.
A note on the calculation of consistent tangent operators for Von Mises and Drucker‐Prager plasticity
Authors: De Borst René , Groen Arend E. 
Published: August 2005

AbstractA comparison is made of implementations of consistent tangent operators that arise in implicit integration of Von Mises and Drucker‐Prager yield criteria. When computing the consistent tangent operator a matrix inversion has to be performed at integration point level. The consequences of different formulations of the consistent tangent operator on the numerical accuracy are assessed.
Application of the spline prism method to analyse vibration of thick rectangular plates with two opposite edges simply supported
Authors: Mizusawa T. , Takagi S. 
Published: August 2005

AbstractThe paper presents an application of the spline prism method to analyse vibration of isotropic, thick rectangular plates with two opposite edges simply supported. Three‐dimensional spline prism models are formulated by combining B‐spline functions with beam eigenfunctions. Because of the orthogonality of the beam functions, three‐dimensional problems are reduced to a series of two‐dimensional ones. To demonstrate the accuracy and convergence of the semi‐numerical method, the results are compared with those obtained by other numerical methods. Good convergence and accuracy are obtained. The effects of the ratio of thickness to width and the aspect ratio on the frequencies of thick rectangular plates with several boundary conditions are analysed, and the results are compared with those calculated by the Mindlin plate theory.
Analytical solutions of mass transport problems for error estimation of finite/infinite element methods
Authors: Zhao Chongbin , Steven G. P. 
Published: August 2005

AbstractIn order to make an exact estimation of discretization error for finite/infinite element methods, it is necessary to develop analytical solutions for some transient mass transport problems in infinite media. These transient mass transport problems may be viewed as the benchmark problems for the discretization error estimation of a new numerical method so that they generally have the following characteristics: (1) their initial and boundary conditions can be exactly modelled by the finite/infinite element method; (2) their solutions can be rigorously expressed in a closed form. In this paper, several of the aforementioned problems have been constructed and solved mathematically for transient mass transport problems in both 1D and 2D infinite media.
Inflow and outflow boundary conditions in the finite element solution of the streamfunction–vorticity equations
Authors: Manzan M. , Comini G. 
Published: August 2005

AbstractThe appropriate specification of boundary conditions is the main difficulty in the finite element solution of the streamfunction–vorticity equations for two‐dimensional incompressible laminar flows. In this context, we show that the appropriate specification of both the outflow and the inflow boundary conditions is required for the successful modelling of two well known test problems.
A B‐spline finite element method for the regularized long wave equation
Authors: Gardner L. R. T. , Gardner G. A. , Dag I. 
Published: August 2005

AbstractA B‐spline finite element method is used to solve the regularized long wave equation numerically. This approach involves a Galerkin method with quadratic B‐spline finite elements so that there is continuity of the dependent variable and its first derivative throughout the solution range. Time integration of the resulting system of ordinary differential equations is effected using a Crank‐Nicolson approximation. Standard problems are used to validate the algorithm, which is then used to model the smooth development of an undular bore.
Modified calculation of the dissipation term in thermoplastic finite element equations
Authors: Szabó László , Varga Imre 
Published: August 2005

AbstractIn the paper, a simple modification of the internal dissipation term in coupled thermoplastic finite element equations is presented. A modified form of the heat capacity and the thermomechanical coupling matrices are derived. These modifications are based on a decomposition of the internal dissipation term into two parts, which depend on the total strain rate and the rate of temperature change, respectively.
A quadratic boundary element for potential problems in 2D with no numerical integration
Authors: Verhoeven N. A. , Morgan K. 
Published: August 2005

AbstractBoth the logarithmic and derivative kernel integrations for potential problems, solved with quadratic isoparametric boundary elements, contain quartic functions of the integration parameter. It is shown that such functions can be written as the product of two quadratic functions with real coefficients. The derivative kernel integration is then represented as the sum of two integrals, which can be evaluated analytically. The logarithmic kernel integration can be similarly split but needs a Taylor series expansion of the Jacobian of the integration to enable analytical integration. The use of this Taylor series expansion means that the method presented is limited to problems involving weakly curved elements.
A Fourier boundary integral method for solving Laplace's equation in two dimensions
Authors: Huestis Stephen P. 
Published: August 2005

AbstractLaplace's equation in two dimensions can be solved by a boundary integral method which imposes the required consistency relation between the boundary function and its outward normal gradient. Rather than incorporating this into a standard boundary element approach for the Dirichlet problem, the known boundary function and the unknown boundary gradient are here expressed as truncated Fourier series expansions. The consistency relation then becomes an algebraic relation between expansion coefficients, whose matrix entries can be found by appropriate applications of the fast Fourier transform. This is solved for the boundary gradient coefficients; the solution can then be evaluated at any interior point. Numerical experiments explore the effect of the truncation level, and indicate that reasonable accuracy can be attained without needing a prohibitively large number of Fourier coefficients.
Solution of multiple‐edge crack problem of elastic half‐plane by using singular integral equation approach
Authors: Chen Y. Z. , Hasebe Norio 
Published: August 2005

AbstractThe complex potential for a single‐edge crack problem of an elastic half‐plane is proposed. The complex potential is obtained by distributing the dislocation density along the crack configuration, and satisfies the traction‐free condition along the boundary of the half‐plane. The multiple‐edge crack problem of an elastic half‐plane can be considered as a superposition of many single‐edge crack problems. Bearing this in mind, a singular integral equation for the multiple‐edge crack problem is formulated, where the distributing dislocation density serves as the unknown function and the traction applied on the crack faces serves as the right‐hand side in the resulting integral equation. A semi‐open quadrature rule is used to solve the singular integral equation. Several numerical examples are given. The ‘shadow effect’ is observed, which means the stress intensity factor at a crack tip is negligible if the crack is placed in some particular ‘shadow area’.
Improved element stresses for node and element patches using superconvergent patch recovery
Authors: Wiberg N.‐E. , Abdulwahab F. , Ziukas S. 
Published: August 2005

AbstractMethods to calculate improved postprocessed stresses in elements for the superconvergent patch recovery technique are developed. Based on improved stresses on node patches, the improved element stresses are obtained by using weighting of patch solutions from different patch assembly points. An alternative method is to directly calculate the element stresses for an element patch based on weighted information. Numerical examples show that the performances of the two procedures are of about the same quality.
A new boundary element/mathematical programming method for contact problems with friction
Authors: Zhu Changming 
Published: August 2005

AbstractThe contact condition is described as a linear complementarity form with penalty parameters. Based on the boundary element discretization, a mathematical programming method for elastic contact problems with friction is presented. This method avoids the tiresome iterative procedures used in previous work and, if there is no unloading, only one incremental step is necessary for a solution. Two examples are given to demonstrate the correctness and effectiveness of the method.
A special incremental–iterative solution technique for non‐linear structural analysis including snap‐through
Authors: Ravichandran R. V. , Sridharan S. 
Published: August 2005

AbstractA special incremental‐iterative solution method for non‐linear finite element structural analysis including snap‐through is presented. As an alternative to the direct solution methods, a special iterative strategy along with the pseudoload method is employed within each Newton‐Raphson iteration step. Two new developments concerning the pseudoload method and the special iterative strategy, which were originally conceived and applied for the non‐linear analysis of shells of revolution using a semi‐analytical method, are presented. Firstly, the underlying principles of the method are utilized in solving general non‐linear structural mechanics problems. Secondly, the capability of the method is enhanced for tracing the load‐displacement curve beyond the critical load by integrating the arc length method. Special modifications are proposed to handle situations with a non‐positive‐definite tangential stiffness matrix. Numerical examples with snap‐through and snap‐back phases in the load‐deflection path are presented to demonstrate the applicability and accuracy of this approach. Results obtained from this numerical study verify the usefulness of this method as an alternative to the conventional direct methods or iterative methods of solving linearized equations in an incremental non‐linear analysis.
Free and forced vibrations of a Timoshenko beam with any number of translational and rotational springs and lumped masses
Authors: Wu Jong‐Shyong , Huang Chang‐Guey 
Published: August 2005

AbstractThe free vibration and the forced dynamic responses of a uniform cantilever Timoshenko beam carrying any number of concentrated masses, translational and rotational springs and subjected to various external loadings are studied by means of the analytical‐and‐numerical‐combined method (ANCM), where the locations and the magnitudes of the masses, springs and loadings are arbitrary. First of all, the (exact) closed‐form solutions for the natural frequencies and the normal mode shapes of the ‘unconstrained’ Timoshenko beam (without carrying any concentrated elements) are determined; then the eigenvalue equation for free vibration analysis and the equation of motion for forced vibration analysis of the ‘constrained’ Timoshenko beam (carrying the prescribed concentrated elements) are derived analytically by applying the expansion theorem and the mode superposition methodology; finally the approximate natural frequencies and mode shapes of the ‘constrained’ Timoshenko beam and its dynamic responses due to external excitations are calculated numerically. It is found that the ANCM presented in the paper has the advantages of both the pure analytical method (to be able to save computing time) and the pure numerical method (to be able to solve various practical problems).
A generalized Newton–Raphson method using curvature
Authors: Lee In‐Won , Jung Gil‐Ho 
Published: August 2005

AbstractA numerical method for finding the roots of any function is developed. This method considers a circle using the concept of curvature instead of the tangential line in the Newton‐Raphson method. The compared results between the proposed method and the Newton‐Raphson method are listed. The proposed method has a wider convergent region of initial points and finds more proper solutions than the Newton‐Raphson method. In particular, the paper proposes that the curvature method is replaced by the modified Newton method discussed by Ralston in dealing with multiple roots.
Comparison of three commercially available antibodies for flow cytometric monitoring of P‐glycoprotein expression in tumor cells
Authors: Krishan Awtar , Sauerteig Antonieta , Stein Jeanne H. 
Published: August 2005

AbstractCellular drug resistance to natural products is often due to the presence of an efflux pump which reduces intracellular drug content and chemosensitivity. A 170 kD cell surface resident P‐glycoprotein is believed to act as the efflux pump. In the present report, we have compared three commercially available antibodies C‐219, JSB‐1, and mdr(Ab‐1) for use in flow cytometric detection of P‐glycoprotein positive cells. Our data show that C219 gives uniformly good results in a variety of murine and human tumor cell lines for detection of P‐glycoprotein positive cells. We have also compared data of C219 stained cells analyzed in parallel on a flow cytometer equipped with a small laser (15 mW) and a large laser (5 watt) cell sorter. Data obtained on these two instruments are comparable. A staining protocol and data on dual staining of cells for DNA content by propidium iodide and P‐glycoprotein expression after FITC labeling are also presented.
Flow cytometric and biochemical analysis of dose‐dependent effects of sodium butyrate on human endometrial adenocarcinoma cells
Authors: Saito Satoshi , Crissman Harry A. , Nishijima Mitsushige , Kagabu Teruo , Nishiya Iwao , Cram L. Scott 
Published: August 2005

AbstractSodium butyrate (SB) treatment was previously shown to produce seven‐fold increases in estrogen hormone receptor binding sites of human endometrial adenocarcinoma (IK) cells. Flow cytometric analysis and histone gel electrophoresis were used to examine cell cycle, cell metabolism, and nuclear histone fractions in IK cells treated with different concentrations of SB. SB‐treated cells stained with fluorochromes specific for DNA, RNA, or general protein were analyzed by flow cytometry (FCM).Changes in accessibility to three DNA stains and gel electrophoresis were used to analyze rearrangements in chromatin structure. SB caused an accumulation of cells in the G1 phase and inhibited DNA synthesis, but not cellular levels of RNA and protein. Hoechst accessibility to A‐T rich regions on DNA was dramatically increased after removal of SB. H1 histones were dephosphorylated and core histones were acetylated during SB‐treatment.Information obtained in these studies may be useful for correlating cellular and biochemical events with SB‐induced increases in nuclear steroid hormone binding sites.
Mono and Bridged Azolium Picrates as Energetic Salts
Authors: Jin Chuan‐Ming , Ye Chengfeng , Piekarski Crystal , Twamley Brendan , Shreeve Jean’ne M. 
Published: August 2005

AbstractThe energetic mono and bridged imidazolium, triazolium and tetrazolium picrates 7–10, 14, and 16, the dipicrates 23, 25, and 26 and the dinitrates 24, and 27 were synthesized by the quaternization of azolium derivatives (1, 2, 13, 15, 19 and 20) with picric acid and nitric acid or by metathesis of the corresponding quaternary salts (3, 6, 21 and 22) with silver picrate or silver nitrate. The structures of 14 and 16 were determined by single‐crystal X‐ray diffraction analysis confirming quaterization on the triazolium and tetrazolium rings. Their physical and thermodynamic properties were determined. In some cases, the salts are thermally stable to ca. 300 °C and they exhibit densities averaging ca. 1.6 g/cm3. Nearly all have positive heats of formation with the highest calculated value, ΔfHom = 611.6 kJ/mol, found for 3‐azido‐1,4‐dimethyl‐1,2,4‐triazolium picrate (10). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The cause and cure (!) of the spurious pressures generated by certain fem solutions of the incompressible Navier‐Stokes equations: Part 2
Authors: Sani R. L. , Gresho P. M. , Lee R. L. , Grifftths D. F. , Engelman M. 
Published: August 2005

AbstractThe spurious pressures and ostensibly acceptable velocities which sometimes result from certain FEM approximate solutions of the incompressible Navier‐Stokes equations are explained in detail. The concept of pressure modes, physical and spurious, pure and impure, is introduced and their effects on discretized solutions is analysed, in the context of mixed interpolation and penalty approaches. Pressure filtering schemes, which are capable of recovering useful pressures from otherwise polluted numerical results, are developed for two particular elements in two‐dimensions and one element in three‐dimensions. The automatic pressure filter associated with the penalty method is also explained. Implications regarding the effect of spurious pressure modes on accuracy and ultimate convergence with mesh refinement are discussed and a list of unanswered questions presented. Sufficient numerical examples are discussed to corroborate the theory presented herein.
Hermitian space‐time finite elements for estuarine mass transport
Authors: Sobey R. J. 
Published: August 2005

AbstractSpace‐time finite element solutions of the convection–dispersion equation using higher‐order nodal continuity and Hermitian polynomial shape functions are described. Five separate elements ranging from a complete linear element with C0,0 nodal continuity to a complete first‐order Hermitian element with C1,1 nodal continuity are subjected to detailed analysis. Wave deformation analyses identify the source of leading or trailing edge oscillations, trailing edge oscillations being the major source of difficulty. These observations are confirmed by numerical experiments which further demonstrate the potential of higher‐order nodal continuity. The performance of the complete first‐order Hermitian element is quite satisfactory and measurably superior to the linear element.
Finite element, stream function–vorticity solution of steady laminar natural convection
Authors: Stevens W. N. R. 
Published: August 2005

AbstractStream function–vorticity finite element solution of two‐dimensional incompressible viscous flow and natural convection is considered. Steady state solutions of the natural convection problem have been obtained for a wide range of the two independent parameters. Use of boundary vorticity formulae or iterative satisfaction of the no‐slip boundary condition is avoided by application of the finite element discretization and a displacement of the appropriate discrete equations. Solution is obtained by Newton–Raphson iteration of all equations simultaneously. The method then appears to give a steady solution whenever the flow is physically steady, but it does not give a steady solution when the flow is physically unsteady. In particular, no form of asymmetric differencing is required. The method offers a degree of economy over primitive variable formulations. Physical results are given for the square cavity convection problem. The paper also reports on earlier work in which the most commonly used boundary vorticity formula was found not to satisfy the no‐slip condition, and in which segregated solution procedures were attempted with very minimal success.