bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Taylor‐least squares finite element to three‐dimensional advection‐diffusion equation
Authors: Park N.‐S. , Liggett J. A. 
Published: October 2005

AbstractThe Taylor‐least squares (TLS) scheme, developed to solve the unsteady advection‐diffusion equation for advection‐dominated cases in one and two dimensions, is extended to three dimensions and applied to some 3D examples to demonstrate its accuracy. The serendipity Hermite element is selected as an interpolation function on a linear hexagonal element. As a validation of the code and as a simple sensitivity analysis of the scheme on the different types of shape functions, the 2D example problem of the previous study is solved again. Four 3D problems, two with advection and two with advection‐diffusion, are also solved. The first two examples are advection of a steep 3D Gaussian hill in rotational flow fields. For the advection‐diffusion problems with fairly general flow fields and diffusion tensors, analytical solutions are obtained using the ray method. Despite the steepness of the initial conditions, very good agreement is observed between the analytical and TLS solutions.
The simulation of inviscid, compressible flows using an upwind kinetic method on unstructured grids
Authors: Mathur J. S. , Weatherill N. P. 
Published: October 2005

AbstractA kinetic flux‐vector‐splitting method has been used to solve the Euler equations for inviscid, compressible flow on unstructured grids. This method is derived from the Boltzmann equation and is an upwind, cell‐centered, finite volume scheme with an explicit time‐stepping procedure. The Delaunay triangulation has been used to generate the grids. The approach is demonstrated for three flow field simulations, namely the subsonic flow over a two‐component high‐lift aerofoil, the transonic flow over an aerofoil and the supersonic flow in a channel.
A numerical study of the laminar incompressible flow over a 6:1 prolate spheroid at 10° incidence
Authors: Rosenfeld Moshe , Wolfshtein Micha , Israeli Moshe 
Published: October 2005

AbstractThe steady incompressible laminar flow field over a 6:1 prolate spheroid at 10° incidence and a Reynolds number of 1·6 × 106 is investigated numerically by solving a reduced set of the Navier‐Stokes equations. The present study moves one step beyond the boundary layer approximation by relaxing the requirement of an imposed pressure field to permit the calculation of both attached and longitudinal vortical flow fields. The results shed light on the flow properties over slender bodies at intermediate incidence. The longitudinal vortex is found to be weak relative to vortex‐dominated flows. Nevertheless, it has pronounced effects on the flow near the surface and on global features of the flow field. A displacement velocity which describes the effect of the vortical flow on the outer inviscid flow is defined. The line on the spheroid where the displacement velocity vanishes closely follows the projection of the vortex centreline on the surface of the spheroid. It is demonstrated numerically that the convergence of the skin friction lines is not a unique criterion for identifying a vortex flow.
Fluid flow and heat transfer test problems for non‐orthogonal grids: Bench‐mark solutions
Authors: Demirdžić I. , Lilek Ž. , Perić M. 
Published: October 2005

AbstractFour problems of fluid flow and heat transfer were designed in which non‐orthogonal, boundary‐fitted grids were to be used. These are proposed to serve as test cases for testing new solution methods. This paper presents solutions of the test problems obtained by using a multigrid finite volume method with grids of up to 320 × 320 control volumes. Starting from zero fields, iterations were performed until the sum of the absolute residuals had fallen seven orders of magnitude, thus ensuring that the variable values did not change to six most significant digits. By comparing the solutions for successive grids at moderate Reynolds and Rayleigh numbers, the discretization errors were estimated to be lower than 0·1%. The results presented in this paper may thus serve for comparison purposes as bench‐mark solutions.
Advection‐diffusion modelling using the modified QUICK scheme
Authors: Chen Yiping , Falconer Roger A. 
Published: October 2005

AbstractIn recent years the QUICK finite difference scheme has been increasingly used in solving the advection‐diffusion equation, particularly for water quality modelling studies relating to coastal and estuarine flows. This scheme has the benefits of mass conservation, reasonably high accuracy and computational efficiency in comparison with many other higher‐order‐accurate schemes reported in the recent literature. A von Neumann stability analysis showed that the explicit QUICK scheme has a severe stability constraint which depends upon the diffusion coefficient. It can be proved that this scheme is numerically unstable for the case of pure advection. Various modified forms of the implicit QUICK scheme have been formulated and their numerical stability properties have been studied and analysed. The modified QUICK schemes considered have been tested for transient simulations for the cases of pure advection and of advection and diffusion in an idealized one‐dimensional basin using three different initial boundary conditions: (a) a sharp front concentration gradient, (b) a Gaussian concentration distribution and (c) a plug source. Details of the comparisons between these modified schemes and with other typical second‐order‐accurate difference schemes are given, together with comparisons with the analytical solutions for each case. A two‐dimensional version of the semi‐time‐centred QUICK scheme (ADI‐QUICK), has also been applied to a two‐dimensional test case using the standard ADI technique and has been shown to be attractive in comparison with other comparable second‐order schemes.
Numerical study on the two‐phase flow distribution in a T‐junction
Authors: Moura L. F. M. , Rezkallah K. S. 
Published: October 2005

AbstractThe main objective of this paper is to investigate the ability of a two‐dimensional two‐fluid computer code to predict the phase separation in a T‐junction. A new semi‐implicit numerical scheme is developed for solving the two‐fluid model equations. Special attention is directed to the modelling of the constitutive for the interfacial friction term. Detailed distribution of void fraction, pressure and velocities are obtained for an air–water mixture in a vertical tee. Good agreement was obtained between the computer code results and the experimental data for the phase separation in the T‐junction.
Numerical computations of two‐dimensional solitary waves generated by moving disturbances
Authors: Cao Yusong , Beck Robert F. , Schultz William W. 
Published: October 2005

AbstractTwo‐dimensional solitary waves generated by disturbances moving near the critical speed in shallow water are computed by a time‐stepping procedure combined with a desingularized boundary integral method for irrotational flow. The fully non‐linear kinematic and dynamic free‐surface boundary conditions and the exact rigid body surface condition are employed. Three types of moving disturbances are considered: a pressure on the free surface, a change in bottom topography and a submerged cylinder. The results for the free surface pressure are compared to the results computed using a lower‐dimensional model, i.e. the forced Korteweg–de Vries (fKdV) equation. The fully non‐linear model predicts the upstream runaway solitons for all three types of disturbances moving near the critical speed. The predictions agree with those by the fKdV equation for a weak pressure disturbance. For a strong disturbance, the fully non‐linear model predicts larger solitons than the fKdV equation. The fully non‐linear calculations show that a free surface pressure generates significantly larger waves than that for a bottom bump with an identical non‐dimensional forcing function in the fKdV equation. These waves can be very steep and break either upstream or downstream of the disturbance.
A least squares finite element method for viscoelastic fluid flow problems
Authors: Wang K. C. , Carey G. F. 
Published: October 2005

AbstractViscoelastic flows remain a demanding class of problems for approximate analysis, particularly at increasing Weissenberg numbers. Part of the difficulty stems from the convective behavior and in the treatment of the stress field as a primary unknown. This latter aspect has led to the use of higher‐order piecewise approximations for the stress approximation spaces in recent finite element research. The computational complexity of the discretized problem is increased significantly by this approach but at present it appears the most viable technique for solving these problems. Motivated by recent success in treating mixed systems and convective problems, we formulate here a least squares finite element method for the viscoelastic flow problem. Numerical experiments are conducted to test the method and examine its strengths and limitations. Some difficulties and open issues are identified through the numerical experiments. We consider the use of high degree elements (p refinement) to improve performance and accuracy.
Enhancing the mechanical integrity of the implant–bone interface with BoneWelding® technology: Determination of quasi‐static interfacial strength and fatigue resistance
Authors: Ferguson Stephen J. , Weber Urs , von Rechenberg Brigitte , Mayer Joerg 
Published: October 2005

AbstractThe BoneWelding® technology is an innovative bonding method, which offers new alternatives in the treatment of fractures and other degenerative disorders of the musculoskeletal system. The BoneWelding process employs ultrasonic energy to liquefy a polymeric interface between orthopaedic implants and the host bone. Polymer penetrates the pores of the surrounding bone and, following a rapid solidification, forms a strong and uniform bond between implant and bone. Biomechanical testing was performed to determine the quasi‐static push‐out strength and fatigue performance of 3.5‐mm‐diameter polymeric dowels bonded to a bone surrogate material (Sawbones solid and cellular polyurethane foam) using the BoneWelding process. Fatigue tests were conducted over 100,000 cycles of 20–100 N loading. Mechanical test results were compared with those obtained with a comparably‐sized, commercial metallic fracture fixation screw. Tests in surrogate bone material of varying density demonstrated significantly superior mechanical performance of the bonded dowels in comparison to conventional bone screws (p < 0.01), with holding strengths approaching 700 N. Even in extremely porous host material, the performance of the bonded dowels was equivalent to that of the bone screws. For both cellular and solid bone analog materials, failure always occurred within the bone analog material surrounding and distant to the implant; the infiltrated interface was stronger than the surrounding bone analog material. No significant decrease in interfacial strength was observed following conditioning in a physiological saline solution for a period of 1 month prior to testing. Ultrasonically inserted implants migrated, on average, less than 20 μm over, and interfacial stiffness remained constant the full duration of fatigue testing. With further refinement, the BoneWelding technology may offer a quicker, simpler, and more effective method for achieving strong fixation and primary stability for fracture fixation or other orthopaedic and dental implant applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Induction of chemokines and chemokine receptors CCR2b and CCR4 in authentic human osteoclasts differentiated with RANKL and osteoclast like cells differentiated by MCP‐1 and RANTES
Authors: Kim Michael S. , Magno Carly L. , Day Christopher J. , Morrison Nigel A. 
Published: October 2005

AbstractChemokines MCP‐1 and RANTES are induced when authentic bone resorbing human osteoclasts differentiate from monocyte precursors in vitro. In addition, MCP‐1 and RANTES can stimulate the differentiation of cells with the visual appearance of osteoclasts, being multinuclear and positive for tartrate resistance acid phosphatase (TRAP +). We show here that MIP1α is also potently induced by RANKL during human osteoclast differentiation and that this chemokine also induces the formation of TRAP + multinucleated cells in the absence of RANKL. MIP1α was able to overcome the potent inhibition of GM‐CSF on osteoclast differentiation, permitting the cells to pass through to TRAP + multinuclear cells, however these were unable to form resorption pits. Chemokine receptors CCR2b and CCR4 were potently induced by RANKL (12.6‐ and 49‐fold, P = 4.0 × 10−7 and 4.0 × 10−8, respectively), while CCR1 and CCR5 were not regulated. Chemokine treatment in the absence of RANKL also induced MCP‐1, RANTES and MIP1α. Unexpectedly, treatment with MCP‐1 in the absence of RANKL resulted in 458‐fold induction of CCR4 (P = 1.0 × 10−10), while RANTES treatment resulted in twofold repression (P = 1.0 × 10−4). Since CCR2b and CCR4 are MCP‐1 receptors, these data support the existence of an MCP‐1 autocrine loop in human osteoclasts differentiated using RANKL. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Interleukin‐1β induces osteopontin expression in pulmonary fibroblasts
Authors: Serlin David M. , Kuang Ping Ping , Subramanian Mangalalaxmy , O'Regan Anthony , Li Xinfang , Berman Jeffrey S. , Goldstein Ronald H. 
Published: October 2005

AbstractOsteopontin is a multifunctional matricellular protein identified as one of the most upregulated genes in pulmonary fibrosis. Experimental animal models have identified early pro‐fibrotic cytokines as essential to the pathogenesis of inflammation‐induced pulmonary fibrosis. However, the principal sources of osteopontin in the fibroproliferative lung, and the factors responsible for its induction, have not been fully defined. We isolated primary rat lung fibroblasts in culture to examine the expression and regulation of lung fibroblast‐derived osteopontin. Our results demonstrate a potent and dramatic increase in osteopontin expression induced by interleukin‐1β (IL‐1β), whereas tumor necrosis factor‐α, transforming growth factor‐β, and angiotensin II had minimal effect. Stimulation with IL‐1β resulted in the secretion of soluble osteopontin protein. We found that osteopontin expression by IL‐1β was regulated via signaling primarily through the mitogen‐activated protein kinase member ERK1/2, partially by p38 MAPK, but not at all by JNK. Finally, the mechanism of IL‐1β increase in osteopontin mRNA requires de novo transcription and translation. In conclusion, we find that osteopontin is expressed by primary lung fibroblasts and is potently upregulated by the early inflammatory and pro‐fibrotic cytokine IL‐1β. Activated fibroblasts may be a significant source of osteopontin production during lung fibrogenesis. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Interpolymer Complex between Hydroxypropyl Cellulose and Maleic Acid–Styrene Copolymer: Phase Behavior of Semi‐Dilute Solutions
Authors: Bumbu Gina‐Gabriela , Eckelt John , Wolf Bernhard A. , Vasile Cornelia 
Published: October 2005

AbstractSummary: The phase behavior of a water/hydroxypropyl cellulose/maleic acid–styrene copolymer (H2O/HPC/MAc‐S) system was investigated in the semi‐dilute range by turbidimetry, rheology, and optical microscopy. The two polymers under investigation form interpolymer complexes via hydrogen bonding. In the case of a total polymer concentration of cpol = 5 mg · mL−1 a second phase segregates upon heating the homogeneous ternary system. By applying a constant shear rate ($\dot \gamma$ = 50 s−1) the phase separation temperature of the system is 10–15 °C lower than for an unsheared one. For cpol = 10 mg · mL−1 phase separation has already occurred at room temperature when the two binary polymer solutions are mixed. The distribution of the partners among the coexisting phases was examined by FT‐IR spectroscopy. The stoichiometry of the interpolymeric complex (IPC) was estimated to be HPC/MAc‐S = 40:60 (w/w) independent of cpol.The phase separation temperature of HPC/MAc‐S aqueous mixtures versus the weight fraction of the HPC in the blend.magnified imageThe phase separation temperature of HPC/MAc‐S aqueous mixtures versus the weight fraction of the HPC in the blend.
Cognitive profiles of individual patients with Parkinson's disease and dementia: Comparison with dementia with lewy bodies and Alzheimer's disease
Authors: Janvin Carmen Cristea , Larsen Jan Petter , Salmon David P. , Galasko Douglas , Hugdahl Kenneth , Aarsland Dag 
Published: October 2005

AbstractWe describe the pattern of cognitive profiles within a community‐based sample of patients with Parkinson's disease (PD) and dementia (PDD) using cluster analyses, and compare the results with data from patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Fifty patients with PDD and 39 with AD from Stavanger, Norway, and 62 patients with DLB from San Diego, CA, USA were diagnosed by either standardized clinical procedures or criteria (all PDD and all AD cases) or necropsy (all DLB cases). Four subgroups were identified: two subgroups with a subcortical cognitive profile (one with mild and one with moderate dementia severity), one subgroup with global impairment and severe dementia, and one subgroup with a cortical cognitive profile and moderate dementia. Of the patients with PDD and with DLB, 56% and 55%, respectively, had a subcortical cognitive profile, compared with only 33% of the AD patients. Conversely, 30% of the patients with PDD and 26% of those with DLB had a cortical cognitive profile, compared with 67% of the patients with AD. These findings suggest that in some patients with PDD, frontosubcortical changes are the main contributing factor to dementia, whereas in other patients, cortical and hippocampal changes are more important. © 2005 Movement Disorder Society
Remarks on the wave front of polarization: Polarized solutions for the evolution three‐dimensional Lame system
Authors: Chełminski K. , Łada A. , Sidz L. 
Published: October 2005

AbstractSome remarks complementary to the work of N. Dencker in [1] concerning the wave front of polarization are given. The theorem due to N. Dencker about the propagation of a wave front of polarization is applied to solutions for the evolution of the three‐dimensional Lame system. The propagation of polarized solutions is established.
Decay properties of periodic, radially symmetric solutions of Sine‐Gordon‐type equations
Authors: Scarpellini B. 
Published: October 2005

AbstractWe investigate the radially symmetric, nonlinear wave equation
equation image
and discuss the asymptotic behaviour as r → ∞ of solutions which are T‐periodic in time t. It is shown that only two possibilities of decay can arise, namely polynomial like t−½(n−1) and exponential e−bt for some b > 0. Existence results are obtained.
Outgassing and contamination: Strict solution of a Boltzman‐like model
Authors: Belleni‐Morante A. , Busoni G. 
Published: October 2005

AbstractWe consider a Boltzmann‐like model of a problem of outgassing and contamination in a region ℛ. For simplicity, we assume that ℛ = ℛ1 ∪ ℛ2 ∪ ℛ3, where ℛ1 is the slab {x: −a < x < 0}, ℛ2 = {x:0 < x < b}, ℛ3 = {x: b < x < b1}. ℛ1 is the region where the contaminant particles are produced, ℛ2 is the ‘cavity’ where such particles migrate and interact with some inert gas, usually at low pressure, and ℛ3 is the region which is contaminated by the particles coming from ℛ2. In each of the three regions, the behaviour of the contaminant particles is represented by means of a Boltzmann‐like equation.We prove that such a mathematical problem has a unique positive strict solution, belonging to a suitable Banach space Y. A system of ordinary differential equations is also derived, which gives the global balances of the contaminant particles in each of the three regions.
A solution formula for a non‐convex scalar hyperbolic conservation law with monotone initial data
Authors: Kunik Matthias 
Published: October 2005

AbstractIn this paper we prove an explicit representation formula for the solution of a one‐dimensional hyperbolic conservation law with a non‐convex flux function but monotone initial data. This representation formula is similar to those of Lax [10] and Kunik [7,8] and enables us to compute the solution pointwise explicitly. This result is a generalization of a theorem given in Kunik [8] where the case of only one inflexion point for the fluxes was considered. Its proof uses the polygonal method of Dafermos [2]. The application of this method leads to a simple explicit construction of the solutions for a Kynch sedimentation process [9] and to an explicit parameter representation for the shock curves evolving during the sedimentation process.
Finite element approximation of a microstructure evolution
Authors: Roubiček Tomáš 
Published: October 2005

AbstractThe evolution model of a microstructure described as appropriately generalized Young measures, which was developed in [11], is discretized here by means of a suitably adapted finite element method. The convergence of the approximate solutions is proved, and a one‐dimensional example is treated to discuss some implementation experience and to show some illustrative results.
Continuous dependence of the scattering amplitude on the surface of an obstacle
Authors: Ramm A. G. 
Published: October 2005

AbstractLet Dj,j = 1,2, be two bounded domains (obstacles) in ℝn, n ≥ 2, with the boundaries Γj. Let Aj be the scattering amplitude corresponding to Dj. The Dirichlet boundary condition is assumed on Γj. A formula is derived for A:= A1 − A2. This formula is used for a derivation of the estimate of ∣A1 − A2∣ in terms of the distance d(Γ1, Γ2) between Γ1 and Γ2. If d(Gamma;1, Gamma;2) ⩽ ϵ, then ∣A∣ ⩽ cϵ, where c is a positive constant which depends on Γ1 and Γ2 provided that one of the boundaries is of C1,λ class, 0 < λ < 1, and the other one is a polyhedron which approximates the first one. The results are useful, in particular, for boundary elements method of solving scattering problems.
Vacuum and non‐vacuum solutions of the quasi‐hydrodynamic semiconductor model in thermal equilibrium
Authors: Unterreiter A. 
Published: October 2005

AbstractThe quasi‐hydrodynamical model for bipolar semiconductor devices in thermal equilibrium admits in general solutions for which the non‐negative electron‐ or hole‐density is not strict positive. In this paper sufficient conditions depending on the device's data which lead to or prevent vacuum are presented. The transformation of the model equations to a single semilinear elliptic mixed boundary value problem for the electrostatic potential V reduces the vacuum‐non‐vacuum discussion to an investigation of the range of V. Monotonicity arguments and the employment of local sub‐ and supersolutions allow to estimate the size as well as the distance from the Dirichlet boundary of the respective vacuum sets. An one‐dimensional model is analysed in some detail.
Parallel block preconditioning based on SSOR and MILU
Authors: Washio Takumi , Hayami Ken 
Published: October 2005

AbstractTwo kinds of parallel preconditioners for the solution of large sparse linear systems which arise from the 2‐D 5‐point finite difference discretization of a convection‐diffusion equation are introduced. The preconditioners are based on the SSOR or MILU preconditioners and can be implemented on parallel computers with distributed memories. One is the block preconditioner, in which the interface components of the coefficient matrix between blocks are ignored to attain parallelism in the forward‐backward substitutions. The other is the modified block preconditioner, in which the block preconditioner is modified by taking the interface components into account. The effect of these preconditioners on the convergence of preconditioned iterative methods and timing results on the parallel computer (Cenju) are presented.