bluuebunny/crossref_metadata_2025_split huggingface dataset:
Moving particle finite element method
Authors: Hao Su , Park Harold S. , Liu Wing Kam 
Published: October 2002

AbstractThis paper presents the fundamental concepts behind the moving particle finite element method, which combines salient features of finite element and meshfree methods. The proposed method alleviates certain problems that plague meshfree techniques, such as essential boundary condition enforcement and the use of a separate background mesh to integrate the weak form. The method is illustrated via two‐dimensional linear elastic problems. Numerical examples are provided to show the capability of the method in benchmark problems. Copyright © 2001 John Wiley & Sons, Ltd.
A stream function implicit finite difference scheme for 2D incompressible flows of Newtonian fluids
Authors: Bubnovich Valeri I. , Rosas César E. , Moraga Nelson O. 
Published: October 2002

AbstractThe development of a new algorithm to solve the Navier–Stokes equations by an implicit formulation for the finite difference method is presented, that can be used to solve two‐dimensional incompressible flows by formulating the problem in terms of only one variable, the stream function. Two algebraic equations with 11 unknowns are obtained from the discretized mathematical model through the ADI method. An original algorithm is developed which allows a reduction from the original 11 unknowns to five and the use of the Pentadiagonal Matrix Algorithm (PDMA) in each one of the equations. An iterative cycle of calculations is implemented to assess the accuracy and speed of convergence of the algorithm. The relaxation parameter required is analytically obtained in terms of the size of the grid and the value of the Reynolds number by imposing the diagonal dominancy condition in the resulting pentadiagonal matrixes. The algorithm developed is tested by solving two classical steady fluid mechanics problems: cavity‐driven flow with Re=100, 400 and 1000 and flow in a sudden expansion with expansion ratio H/h=2 and Re=50, 100 and 200. The results obtained for the stream function are compared with values obtained by different available numerical methods, to evaluate the accuracy and the CPU time required by the proposed algorithm. Copyright © 2002 John Wiley & Sons, Ltd.
Chebyshev rational spectral and pseudospectral methods on a semi‐infinite interval
Authors: Guo Ben‐yu , Shen Jie , Wang Zhong‐qing 
Published: October 2002

AbstractA weighted orthogonal system on the half‐line based on the Chebyshev rational functions is introduced. Basic results on Chebyshev rational approximations of several orthogonal projections and interpolations are established. To illustrate the potential of the Chebyshev rational spectral method, a model problem is considered both theoretically and numerically: error estimates for the Chebyshev rational spectral and pseudospectral methods are established; preliminary numerical results agree well with the theoretical estimates and demonstrate the effectiveness of this approach. Copyright © 2001 John Wiley & Sons, Ltd.
A p‐adaptive algorithm for the BEM with the hypersingular operator on the plane screen
Authors: Heuer Norbert , Mellado Mario E. , Stephan Ernst P. 
Published: October 2002

AbstractWe propose a p‐adaptive algorithm for the Galerkin method solving the hypersingular integral operator of the Laplacian on the plane screen. The error indicators/estimators are based on projections of the actual error onto local subspaces. These subspaces are defined by decompositions of specially designed enriched ansatz spaces. Our algorithm uses different strategies for the refinement and the stopping criterion. The error estimator that stops the algorithm is based on an overlapping decomposition of an ansatz space that is defined by mesh refinement. The error indicators that steer the p‐refinement are computed via an almost direct decomposition of an enriched ansatz space that uses the same mesh but higher polynomial degrees. Numerical results support the efficiency of our algorithm. Copyright © 2001 John Wiley & Sons, Ltd.
Hybrid‐stress solid elements for shell structures based upon a modified variational functional
Authors: Sze K. Y. , Lo S. H. , Yao L.‐Q. 
Published: October 2002

AbstractIn this paper, we start with a modified generalized laminate stiffness matrix that serves as a remedy to resolve the thickness locking and some abnormalities encountered by solid‐shell elements in laminate analyses. A modified Hellinger–Reissner functional having displacement and a set of generalized stresses as independent fields is devised. Based upon the functional, eight‐node and 18‐node hybrid‐stress solid‐shell elements are proposed. A number of benchmark tests on homogenous and laminated plates/shells are conducted. The accuracy of the elements is promising. Copyright © 2002 John Wiley & Sons, Ltd.
Remeshing for metal forming simulations—Part I: Two‐dimensional quadrilateral remeshing
Authors: Kwak Dae‐Young , Cheon Jae‐Seung , Im Yong‐Taek 
Published: October 2002

AbstractIn this paper, a general framework of practical two‐dimensional quadrilateral remeshing, which includes the determination of remeshing time, automatic quadrilateral mesh generation, and data transfer process, will be formulated. In particular, the current work contains new algorithms of mesh density specification according to the distribution of effective strain‐rate gradients, mesh density smoothing by fast Fourier transform (FFT) and low‐pass filtering techniques, coarsening it by node placement scheme, and a modified Laplacian mesh smoothing technique. The efficiency of the developed remeshing scheme was tested through three practical two‐dimensional metal forming simulations. The results clearly indicate that the algorithms proposed in this study make it possible to simulate two‐dimensional metal forming problems efficiently and automatically. Copyright © 2002 John Wiley & Sons, Ltd.
An optimal high‐order non‐reflecting finite element scheme for wave scattering problems
Authors: Givoli Dan , Patlashenko Igor 
Published: October 2002

AbstractA new finite element scheme is proposed for the numerical solution of time‐harmonic wave scattering problems in unbounded domains. The infinite domain in truncated via an artificial boundary ℬ︁ which encloses a finite computational domain Ω. On ℬ︁ a local high‐order non‐reflecting boundary condition (NRBC) is applied which is constructed to be optimal in a certain sense. This NRBC is implemented in a special way, by using auxiliary variables along the boundary ℬ︁, so that it involves no high‐order derivatives regardless of its order. The order of the scheme is simply an input parameter, and it may be arbitrarily high. This leads to a symmetric finite element formulation where standard C0 finite elements are used in Ω. The performance of the method is demonstrated via numerical examples, and it is compared to other NRBC‐based schemes. The method is shown to be highly accurate and stable, and to lead to a well‐conditioned matrix problem. Copyright © 2002 John Wiley & Sons, Ltd.
Automatic generation of anisotropic quadrilateral meshes on three‐dimensional surfaces using metric specifications
Authors: Lee Y. K. , Lee C. K. 
Published: October 2002

AbstractA new algorithm for constructing full quadrilateral anisotropic meshes on 3D surfaces is proposed in this paper. The proposed method is based on the advancing front and the systemic merging techniques. Full quadrilateral meshes are constructed by systemically converting triangular elements in the background meshes into quadrilateral elements.By using the metric specifications to describe the element characteristics, the proposed algorithm is applicable to convert both isotropic and anisotropic triangular meshes into full quadrilateral meshes. Special techniques for generating anisotropic quadrilaterals such as new selection criteria of base segment for merging, new approaches for the modifications of the background mesh and construction of quadrilateral elements, are investigated and proposed in this study. Since the final quadrilateral mesh is constructed from a background triangular mesh and the merging procedure is carried out in the parametric space, the mesh generator is robust and no expensive geometrical computation that is commonly associated with direct quadrilateral mesh generation schemes is needed. Copyright © 2002 John Wiley & Sons, Ltd.
Extended preconditioners for the FETI method applied to constrained problems
Authors: Rixen Daniel J. 
Published: October 2002

AbstractAn efficient and simple approach for handling linear multipoint constraints in a class of substructure‐based solvers, namely the finite element tearing and interconnecting (FETI) method, is proposed. Previously, it was argued that multipoint constraints should be handled in FETI by adding a second level iteration on a coarse grid such that the FETI iterates satisfy the multipoint constraints exactly. The procedure presented here does not require an additional coarse grid but instead takes account of the multipoint constraints in the preconditioning step. The preconditioning strategy is shown to be mechanically consistent and to incur only a small additional computational cost. This strategy is simpler and computationally less expensive than the two‐level FETI procedure. Its numerical scalability even for highly heterogeneous problems is demonstrated in several test examples. Copyright © 2002 John Wiley & Sons, Ltd.
Large strain finite element analysis of a local second gradient model: application to localization
Authors: Matsushima Takashi , Chambon René , Caillerie Denis 
Published: October 2002

AbstractA large strain finite element formulation based on a local second gradient plasticity model is presented. The corresponding constitutive equations were developed as a direct extension of microstructured (SIAM J. Appl. Math. 1973; 25(3):556–575; Arch. Rational Mech. Anal. 1964; 16:51–78) or micromorphic (In Mechanics of Generalized Continua, IUTAM Symposium, Kröner (ed.), Springer: Berlin, 1968; 18–35; J. Math. Mech. 1966; 15(6):909–924.) continua in which a mathematical constraint between the micro kinematics description and the usual macrodeformation gradient field has been introduced. This constraint is enforced in a weak sense by the use of Lagrange multipliers in order to avoid difficulties with the C1 continuity, for the finite element method. Corresponding finite elements are then constructed involving the Lagrange multipliers field. A geometrically non‐linear 2‐D finite element code is developed within a framework of an incremental method. For every step, a full Newton–Raphson involving a numerical consistent tangent stiffness operator for the complete model (i.e., the second gradient terms as well as the classical ones) is done and some numerical tests allow to validate the method and to discuss the influence of the geometrical non‐linearity. Copyright © 2002 John Wiley & Sons, Ltd.
Testing the asymptotic behaviour of shell elements—Part I: the classical benchmark tests
Authors: Briassoulis D. 
Published: October 2002

AbstractThe asymptotic behaviour is considered to be one of the most demanding levels of benchmark testing for shell elements. In the present paper, the asymptotic behaviour of classical benchmark problems is analytically and numerically investigated. The aim is to examine the possibility of using the classical benchmark tests for testing the asymptotic behaviour of shell elements. Appropriate analytical approaches are introduced to investigate the asymptotic behaviour of the classical benchmark problems. The reformulated four‐node shell element (RFNS) is employed in the numerical analyses. It is shown that the classical benchmark tests, in addition to testing the reliability and robustness of shell elements, also represent strong challenging tests for the asymptotic behaviour of shell elements. In the course of the numerical investigation of the asymptotic behaviour of the classical benchmark problems, the reliability and efficiency of the RFNS element already established by means of the classical configuration of the benchmark tests is re‐confirmed in all cases of the corresponding asymptotic test configurations. Copyright © 2002 John Wiley & Sons, Ltd.
Elastic wave propagation in a 3‐D unbounded random heterogeneous medium coupled with a bounded medium. Application to seismic soil–structure interaction (SSSI)
Authors: Savin E. , Clouteau D. 
Published: October 2002

AbstractWe present a sub‐structuring method for the coupling between a large elastic structure, and a stratified soil half‐space exhibiting random heterogeneities over a bounded domain and impinged by incident waves. Both media are also weakly dissipative. The concept of interfaces classically used in sub‐structuring methods is extended to ‘volume interfaces’ in the proposed approach. The random dimension of the stochastic fields modelling the heterogeneities in the soil is reduced by introducing a Karhunen–Loéve expansion of these stochastic fields. The coupled overall problem is solved by Monte‐Carlo simulation techniques. A realistic example of a large industrial structure interacting with an uncertain stratified soil medium under earthquake is finally presented. This case study and others validate the presented methodology and its ability to handle complex mechanical systems. Copyright © 2002 John Wiley & Sons, Ltd.
Numerical inclusion methods of solutions for variational inequalities
Authors: Ryoo C. S. , Agarwal R. P. 
Published: October 2002

AbstractWe consider a numerical method that enables us to verify the existence of solutions for variational inequalities. This method is based on the infinite dimensional fixed point theorems and explicit error estimates for finite element approximations. Using the finite element approximations and explicit a priori error estimates, we present an effective verification procedure that through numerical computation generates a set which includes the exact solution. Copyright © 2002 John Wiley & Sons, Ltd.
A new shear flexible cubic spline plate element for vibration analysis
Authors: Patel B. P. , Ganapathi M. 
Published: October 2002

AbstractHere, a new cubic B‐spline plate element is developed using field consistency principle, for vibration analysis. The formulation includes anisotropy, transverse shear deformation, in‐plane and rotary inertia effects. The element is based on a laminated refined plate theory, which satisfies the interface transverse shear stress and displacement continuity, and has a vanishing shear stress on the top and bottom surfaces of the plates. The lack of consistency in the shear strain field interpolations in its constrained physical limits produces poor convergence and results in unacceptable solutions due to locking phenomenon. Hence, numerical experimentation for the evaluation of natural frequencies of plates is carried out to check this deficiency with a series of assumed shear strain functions, redistributed in a field consistent manner. Copyright © 2002 John Wiley & Sons, Ltd.
Classical and advanced multilayered plate elements based upon PVD and RMVT. Part 1: Derivation of finite element matrices
Authors: Carrera Erasmo , Demasi Luciano 
Published: October 2002

AbstractThis paper deals with the formulation of finite plate elements for an accurate description of stress and strain fields in multilayered, thick plates subjected to static loadings in the linear, elastic cases. The so‐called zig‐zag form and interlaminar continuity are addressed in the considered formulations. Two variational statements, the principle of virtual displacements (PVD) and the Reissner mixed variational theorem (RMVT) are employed to derive finite element matrices. Transverse stress assumptions are made in the framework of RMVT and the resulting finite elements describe a priori interlaminar continuous transverse shear and normal stresses. Both modellings which preserve the number of variables independent of the number of layers (equivalent single‐layer models, ESLM) and layer‐wise models (LWM) in which the same variables are independent in each layer, have been treated. The order N of the expansions assumed for both displacement and transverse stress fields in the plate thickness direction z as well as the number of element nodes Nn have been taken as free parameters of the considered formulations. By varying N, Nn, variable treatment (LW or ESL) as well as variational statements (PVD and RMVT), a large number of newly finite elements have been presented. Finite elements that are based on PVD and RMVT have been called classical and advanced, respectively.In order to write the matrices related to the considered plate elements in a concise form and to implement them in a computer code (see Part 2), extensive indicial notations have been set out. As a result, all the finite element matrices have been built from only five arrays that were called fundamental nuclei (four are related to RMVT applications and one to PVD cases). These arrays have 3×3 dimensions and are therefore constituted of only nine terms each. The different formulations are then obtained by expanding the indices that were introduced for the N‐order expansion, for the number of nodes Nn and for the constitutive layers Nl. Compliances and/or stiffness are accumulated from layer to multilayered level according to the corresponding variable treatment (ESLM or LWM). The numerical evaluations and assessment for the presented plate elements have been provided in the companion paper (Part 2), where it has been concluded that it is convenient to refer to RMVT as a variational tool to formulate multilayered plate elements that are able to give a quasi‐three‐dimensional description of stress/strain fields in multilayered thick structures. Copyright © 2002 John Wiley & Sons, Ltd.
Local defect correction with different grid types
Authors: Nefedov V. , Mattheij R. M. M. 
Published: October 2002

AbstractFor a Poisson problem with a solution having large gradients in (nearly) circular subregions a local defect correction method is considered. The problem on the global domain is discretized on a cartesian grid, whereas the restriction of the problem to a circular subdomain is discretized on a polar grid. The two discretizations are then combined in an iterative way. We show that LDC can be viewed as an iterative method for the Poisson equation on a single composite cartesian‐polar grid. The efficiency of methods is illustrated by numerical examples. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 454–468, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10018
The involvement of matrix glycoproteins in vascular calcification and fibrosis: an immunohistochemical study
Authors: Canfield A. E. , Farrington C. , Dziobon M. D. , Boot‐Handford R. P. , Heagerty A. M. , Kumar S. N. , Roberts I. S. D. 
Published: October 2002

AbstractCalcification and fibrointimal proliferation are associated with advanced complicated atherosclerosis in large arteries but may also occur in smaller vessels, resulting in ischaemic tissue necrosis. This study investigates whether the mechanisms of calcification and intimal fibrosis are similar in vessels of different sizes. The localization of osteopontin (OPN), matrix Gla protein (MGP), thrombospondin‐1 (TSP‐1), and cartilage oligomeric matrix protein (COMP) was investigated in three types of human vascular lesions: atherosclerosis, chronic vascular rejection (CVR) in renal allografts, and calcific uraemic arteriolopathy (calciphylaxis). These lesions were chosen as they affect different sized blood vessels and they exhibit a fibroproliferative intimal reaction, with or without calcification, resulting in luminal obliteration and ischaemic complications. OPN, MGP, TSP‐1, and COMP were not detected in normal blood vessels. However, OPN and MGP were expressed at sites of calcification within atherosclerotic lesions and in microvessels in calciphylaxis, suggesting that calcification in different sized vessels may occur by a common mechanism. These proteins were not detected in areas of fibrointimal proliferation. In contrast, TSP‐1 was localized primarily within the fibrous tissue of atherosclerotic lesions and was also expressed in the expanded fibrous intima of arteries showing CVR. COMP was localized primarily within the fibrous tissue under the lipid core of the majority of advanced atherosclerotic lesions. TSP‐1 and COMP were also detected in areas of microcalcification in atherosclerotic lesions and TSP‐1 was detected adjacent to areas of calcification in calciphylaxis. However, neither TSP‐1 nor COMP was localized to calcific foci within these lesions. The localization of OPN, MGP, TSP‐1, and COMP to pathological, but not normal arterial intima supports a pathogenetic role for these proteins in the development of vascular fibrosis and calcification. Modulation of their production and activity may offer a novel approach to the therapy of a number of vascular diseases. Copyright © 2001 John Wiley & Sons, Ltd.
Evidence for activation of the renin–angiotensin system in the human prostate: increased angiotensin II and reduced AT1 receptor expression in benign prostatic hyperplasia
Authors: Dinh Diem T. , Frauman Albert G. , Somers Gino R. , Ohishi Mitsuru , Zhou Jialong , Casley David J. , Johnston Colin I. , Fabiani Maurice E. 
Published: October 2002

AbstractThe expression and cellular localization of angiotensin II (Ang II) and AT1 receptor proteins were examined in the normal human prostate and benign prostatic hyperplasia (BPH) by immunohistochemistry. In the normal prostate, Ang II immunoreactivity was localized to the basal layer of the epithelium and AT1 receptor immunostaining was found predominantly on stromal smooth muscle and also on vascular smooth muscle of prostatic blood vessels. Ang II immunoreactivity was markedly increased in hyperplastic acini in BPH compared with acini in the normal prostate (normal: 7.4±0.2%, n=5 vs. BPH: 22.7±1.9%, n=5, p<0.001). However, AT1 receptor immunoreactivity was significantly decreased in BPH compared with the normal prostate [normal: 16.4±2.2%, n=4 vs. BPH: 9.4±1.3%, n=5, p<0.05 (p=0.025)]. The present study demonstrates the presence of Ang II peptide in the basal layer of the epithelium and AT1 receptors on stromal smooth muscle, suggesting that Ang II may mediate paracrine functions on cellular growth and smooth muscle tone in the human prostate. Furthermore, AT1 receptor down‐regulation in BPH may be due to receptor hyperstimulation by increased local levels of Ang II in BPH. These data extend previous findings in support of the novel concept that overactivity of the renin–angiotensin system (RAS) may be involved in the pathophysiology of BPH. Copyright © 2001 John Wiley & Sons, Ltd.
Expression of S100A4 protein is associated with metastasis and reduced survival in human bladder cancer
Authors: Davies Barry R. , O'Donnell Marie , Durkan Garrett C. , Rudland Philip S. , Barraclough Roger , Neal David E. , Kilian Mellon J. 
Published: October 2002

AbstractThe calcium‐binding protein S100A4 induces the metastatic phenotype in rodent models of breast cancer and its expression correlates strongly with reduced survival in human breast cancer. The expression of S100A4 in normal bladders and 101 bladder tumours has been studied using immunocytochemistry. Moderate or strong expression of S100A4 was found in 28% of the tumours, whilst the remaining tumours and normal urothelium either failed to stain or showed weak staining. S100A4 staining was more frequently observed in invasive bladder tumours than in non‐invasive tumours (p<0.05). In invasive tumours, S100A4 staining was usually strongest in invasive regions and single infiltrating cells. Statistically significant associations were found between S100A4 expression and metastasis (p=0.0003) and reduced survival (p<0.0001). It is concluded that S100A4 expression may play an important role in bladder cancer and may identify a subgroup of patients at increased risk of metastasis who should be considered for adjuvant systemic therapy. Copyright © 2002 John Wiley & Sons, Ltd.