bluuebunny/crossref_metadata_2025 huggingface dataset:
Entrance flow in elliptical ducts
Authors: Velusamy K. , Garg Vijay K.
Published: November 2005

A control volume‐based solution of the complete set of Navier–Stokes equations for the laminar, three dimensional developing flow in elliptical cross‐section ducts is described. Numerical results for velocity and pressure development, pressure defect and entrance lengths are presented for a wide range of aspect ratios from 0·1 to 0·999. The present results match very well with earlier numerical solutions for developing flow in a circular duct and the fully developed flow in elliptical ducts. A comparison with earlier numerical and experimental data for developing flow in elliptical ducts is also satisfactory for pressure development but not so good for the velocity profiles. The relative growth rate of boundary layer thickness along the major axis is slower than that along the minor axis which is contrary to the assumption used in earlier numerical analyses. The present results show no transverse recirculation contrary to the speculation based on earlier experimental data. The ratio of entry length in an elliptical duct to that in a circular duct with radius equal to the semi‐major axis of the elliptical duct is nearly equal to the aspect ratio of the duct. In conformity with the previous work, the present results find the total pressure defect to be independent of the aspect ratio, with a value of 1·234.
The calculation of separated flows using a distributed memory mimd computer
Authors: Hardy N. , Murray B. A. , Downie M. J. , Bettess P.
Published: November 2005

A brief description of distributed memory MIMD computers, and in particular, a transputer based computing surface, is presented. The factors to be considered in their application to computationally intensive CFD problems are discussed with reference to the discrete vortex method used for the solution of separated flow about bluff bodies. Three parallel algorithms for its implementation are presented, and the results are discussed in the context of the speed‐ups obtained using up to sixty‐four parallel processors.
Stability of a numerical algorithm for gas bubble modelling
Authors: Barkhudarov M. R. , Chin S. B.
Published: November 2005

A free‐surface‐tracking algorithm based on the SOLA‐VOF method is analysed for numerical stability when modelling gas bubble evolution in a fluid. It is shown that an instability can arise from the fact that the bubble pressure varies with its volume. A time step stability criterion is introduced which is a function of the natural oscillation period but does not depend on the mesh size. This dependence suggests that the instability is likely to arise in the case of a general motion of a bubble, especially if break‐up occurs. The effect is shown using linear Fourier analysis of the discretized equation for radial bubble oscillation and demonstrated numerically using a CFD code FLOW‐3D. One‐ and three‐dimensional situations are considered: a bubble in a fluid bounded by two concentric surfaces and a bubble floating in a fluid chamber with and without gravity. In cases where no analytical solution is available, a numerical method for the stability time step limit calculation is suggested based on finding the natural oscillation frequency.

The nature of the instability suggests that it can be a feature of any numerical algorithm which models transient fluid flow with a free surface.
Fully coupled finite volume solutions of the incompressible Navier–Stokes and energy equations using an inexact Newton method
Authors: McHugh Paul R. , Knoll Dana A.
Published: November 2005

An inexact Newton method is used to solve the steady, incompressible Navier–Stokes and energy equation. Finite volume differencing is employed on a staggered grid using the power law scheme of Patankar. Natural convection in an enclosed cavity is studied as the model problem. Two conjugate‐gradient ‐like algorithms based upon the Lanczos biorthogonalization procedure are used to solve the linear systems arising on each Newton iteration. The first conjugate‐gradient‐like algorithm is the transpose‐free quasi‐minimal residual algorithm (TFQMR) and the second is the conjugate gradients squared algorithm (CGS). Incomplete lower‐upper (ILU) factorization of the Jacobian matrix is used as a right preconditioner. The performance of the Newton‐ TFQMR algorithm is studied with regard to different choices for the TFQMR convergence criteria and the amount of fill‐in allowed in the ILU factorization. Performance data are compared with results using the Newton‐CGS algorithm and previous results using LINPACK banded Gaussian elimination (direct‐Newton). The inexact Newton algorithms were found to be CPU competetive with the direct‐Newton algorithm for the model problem considered. Among the inexact Newton algorithms, Newton‐CGS outperformed Newton‐ TFQMR with regard to CPU time but was less robust because of the sometimes erratic CGS convergence behaviour.
Finite element solution of the streamfunction‐vorticity equations for incompressible two‐dimensional flows
Authors: Comini G. , Manzan M. , Nonino C.
Published: November 2005

The streamfunction‐vorticity equations for incompressible two‐dimensional flows are uncoupled and solved in sequence by the finite element method. The vorticity at no‐slip boundaries is evaluated in the framework of the streamfunction equation. The resulting scheme achieves convergence, even for very high values of the Reynolds number, without the traditional need for upwinding. The stability and accuracy of the approach are demonstrated by the solution of two well‐known benchmark problems: flow in a lid‐driven cavity at Re ⩽ 10,000 and flow over a backward‐facing step at Re = 800.
A numerical approach to model non‐isothermal viscous flow through fibrous media with free surfaces
Authors: Bruschke M. V. , Advani S. G.
Published: November 2005

A numerical simulation is presented to predict the free surface and its interactions with heat transfer and cure for flow of a shear‐thinning resin through the fibre preform the flow part of the simulation is based on the finite element/control volume method. Since the traditional control volume approach produces an error associated with a mass balance inconsistency, a new method which overcomes this issue is proposed, the element control volume method.

The heat transfer and cure analysis in the simulation are based on the finite difference/control volume method. Since heat conduction is dominant in the through‐thickness direction and most of the heat convection is in‐plane, heat transfer and cure are solved in fully three‐dimensional form. A simple concept of the boundary condition constant is introduced which models a realistic mould configuration with a heating element located at a distance behind the mould wall. The varying viscosity throughout the mould associated with the strain rate, temperature and degree of cure distribution may be accounted for in calculating the mould‐filling pattern. This introduces a two‐way coupling between momentum and energy transport in fibrous media during mould filling.
Grid adaptation using a distribution of sources applied to inviscid compressible flow simulations
Authors: Weatherill N. P. , Marchant M. J. , Hassan O. , Marcum D. L.
Published: November 2005

Unstructured tetrahedral grids are generated using a new, very efficient procedure based upon the Delaunay triangulation. The generation procedure is extremely fast, having the capability to generate large grids in minutes on workstations. To maximize this computational performance, a new form of adaptivity has been developed involving the use of sources placed within regions of the domain which require further grid point resolution. A source has a position and a specified grid point density. An error indicator is used to find the elements within the grid which require refinement. Within such elements sources are placed with specified grid point densities which are proportional to the amount of refinement required. The grid generation procedure is then invoked and a grid generated whose grid point density is controlled by the sources. The resulting grid is thus refined in the regions identified by the error indicator as requiring greater resolution. The paper discusses the generation process and emphasizes the new solution adaptation capability. Several examples of the approach are given, including aerospace compressible flow simulations over realistic configurations.
Simulation of supersonic flows with detached shocks using a property convection method
Authors: Milthorpe J. F.
Published: November 2005

An algorithm based on the convection of fundamental flow quantities, i.e. mass, momentum and energy, has been described by the author previously.1 Computer codes to implement the algorithm have been developed for two‐dimensional and axisymmetric flows. This algorithm has been further developed to improve the accuracy and stability of the calculations. In this paper the algorithm is used to calculate the flows about two‐dimensional and axisymmetric bluff bodies. Bodies of practical interest in supersonic and hypersonic flows are often sufficiently bluff for a detached shock to develop, and correct prediction of the shock stand‐off distance and the position of the sonic line is a useful test of numerical methods.

The programme is used to calculate flows with a detached shock around three standard shapes: a sphere, a body of revolution with a flat nose and a plate with a flat nose. The Mach number range for the flows described is from 1.177 to 6.0. Comparisons are given with standard experimental results for the steady state stand‐off.
Simultaneous solution of the Navier‐Stokes and elastic membrane equations by a finite element method
Authors: Rast Mark Peter
Published: November 2005

Fluid flow through a significantly compressed elastic tube occurs in a variety of physiological situations. Laboratory experiments investigating such flows through finite lengths of tube mounted between rigid supports have demonstrated that the system is one of great dynamical complexity, displaying a rich variety of self‐excited oscillations. The physical mechanisms responsible for the onset of such oscillations are not yet fully understood, but simplified models indicate that energy loss by flow separation, variation in longitudinal wall tension and propagation of fluid elastic pressure waves may all be important. Direct numerical solution of the highly non‐linear equations governing even the most simplified two‐dimensional models aimed at capturing these basic features requires that both the flow field and the domain shape be determined as part of the solution, since neither is known a priori. To accomplish this, previous algorithms have decoupled the solid and fluid mechanics, solving for each separately and converging iteratively on a solution which satisfies both. This paper describes a finite element technique which solves the incompressible Navier‐Stokes equatikons simultaneously with the elastic membrane equations on the flexible boundary. The elastic boundary position is parametized in terms of distances along spines in a manner similar to that which has been used successfully in studies of viscous free surface flows, but here the membrane curvature equation rather than the kinematic boundary condition of vanishing normal velocity is used to determine these diatances and the membrane tension varies with the shear stresses exerted on it by the fluid motions. Bothy the grid and the spine positions adjust in response to membrane deformation, and the coupled fluid and elastic equations are solved by a Newton‐Raphson scheme which displays quadratic convergence down to low membrane tensions and extreme states of collapse. Solutions to the steady problem are discussed, along with an indication of how the time‐dependent problem might be approached.
A numerical study of vortex shedding around a heated/cooled circular cylinder by the three‐step Taylor‐Galerkin method
Authors: Hatanaka Katsumori , Kawahara Mutsuto
Published: November 2005

In this paper the vortex shedding around a heated/cooled circular cylinder is numerically simulated by solving the time‐dependent Navier‐Stokes and energy equations. A finite element method that is referred to as the three‐step Taylor‐Galerkin method is used to compute these equations. The attention of this study is directed to the investigation of the effect of buoyancy on the vortex street behind the cylinder at constant Reynolds number. The present paper shows the suppression or generation of the von Kármán vortex street behind the cylinder when the cylinder surface is heated or cooled respectively. The relationship between the temperature‐induced buoyancy force and the vortex shedding is also discussed through several numerical examples.
Wavelet and multiple scale reproducing kernel methods
Authors: Liu Wing Kam , Chen Yijung
Published: November 2005

Multiple scale methods based on reproducing kernel and wavelet analysis are developed. These permit the response of a system to be separated into different scales. These scales can be either the wave numbers corresponding to spatial variables or the frequencies corresponding to temporal variables, and each scale response can be examined separately. This complete characterization of the unknown response is performed through the integral window transform, and a space‐scale and time‐frequency localization process is achieved by dilating the flexible multiple scale window function. An error estimation technique based on this decomposition algorithm is developed which is especially useful for local mesh refinement and convergence studies. This flexible space‐scale window function can be constructed to resemble the well‐known unstructured multigrid and hp‐adaptive finite element methods. However, the multiple scale adaptive refinements are performed simply by inserting nodes into the highest wavelet scale solution region and at the same time narrowing the window function. Hence hp‐like adaptive refinements can be performed without a mesh. An energy error ratio parameter is also introduced as a measure of aliasing error, and critical dilation parameters are determined for a class of spline window functions to obtain optimal accuracy. This optimal dilation parameter dictates the number of nodes covered under the support of a given window function. Numerical examples, which include the Helmholtz equation and the 1D and 2D advection‐diffusion equations, are presented to illustrate the high accuracy of the methods using the optimal dilation parameter, the concept of multiresolution analysis and the meshless unstructured adaptive refinements.
Numerical solution of two‐layer, two‐dimensional tidal flow in a boundary‐fitted orthogonal curvilinear co‐ordinate system
Authors: Chau K. W. , Jin H. S.
Published: November 2005

A new two‐layer, two‐dimensional mathematical model employing a finite difference method based on numerically generated boundary‐fitted orthogonal co‐ordinates and a grid ‘block’ technique for unsteady boundary problems is developed which can be used to simulate flows with density stratification in a natural water‐body with complicated topography. In the model the turbulent exchange across the interface is treated empirically and a time‐splitting finite difference method with two fractional steps is employed to solve the governing equations. The model is calibrated and verified by comparing the computational results with data measured in Tolo Harbour, Hong Kong. The simulation results mimie the field measurements very closely. The computation shows that the model reproduces the two‐layer, two‐dimensional tidal flow with density stratification in Tolo Harbour very well. The computed velocity hodographs show that the tidal circulations at various positions in each layer have different patterns and that the features of the patterns are independent of the tidal type except for their scales. The computed Lagrangian pathlines show that the tidal excursion is dependent on the tidal type, especially in the inner harbour and side‐coves.
Blood and lymph vessels in embryonic tumors
Authors: Rössler Jochen , Lagodny Jeanette
Published: November 2005

Formation of embryonic blood and lymph vessels is mediated by different steps of vasculogenesis and angiogenesis. The vascular endothelial growth factor family (VEGF) as well as the VEGF‐receptors on the surface of blood endothelial cells and lymph endothelial cells are responsible for both processes. In addition to the embryonic development of the vessel systems, the interactions of angiogenesis factors and receptors are also present in solid tumors.

Embryonic tumors in children offer an interesting target for new substances developed for anti‐angiogenesis. Some data on the role of blood vessels and anti‐blood‐angiogenesis are available on embryonic tumors. However, studies of lymph‐angiogenesis are not found and anti‐lymph‐angiogenesis is not at all examined in embryonic tumors.

This review gives an overview of the challenging field of angiogenesis and anti‐angiogenesis of both blood and lymph vessels with a focus on embryonic tumors. Copyright © 2005 John Wiley & Sons, Ltd.
An osteoclastic protein‐tyrosine phosphatase is a potential positive regulator of the c‐Src protein‐tyrosine kinase activity: A mediator of osteoclast activity
Authors: Lau K.‐H. William , Wu Li‐Wha , Sheng Matilda H.‐C. , Amoui Mehran , Suhr Sung Min , Baylink David J.
Published: November 2005

This study tested the hypothesis that an osteoclastic protein‐tyrosine phosphatase, PTP‐oc, enhances osteoclast activity through c‐Src activation. The effects of several resorption activators and inhibitors on PTP‐oc expression, resorption activity, and c‐Src activation were determined in rabbit osteoclasts. PTP‐oc expression was assayed with immunoblots and semi‐quantitative RT‐PCR. Osteoclastic activity was determined by the resorption pit assay; and c‐Src activation was monitored by P‐tyr527 (PY527) dephosphorylation, and in vitro kinase assay. Treatment of osteoclasts with PTH, PGE2, 1,25(OH)2D3, IL‐1, but not RANKL or IL‐6, significantly stimulated resorption activity, increased PTP‐oc mRNA and protein levels, and reduced c‐Src PY527 level with corresponding activation of c‐Src protein‐tyrosine kinase activity. The PTP‐oc antisense phosphorothioated oligo treatment blocked the basal and IL‐1α‐mediated, but not RANKL‐mediated, resorption activity of isolated osteoclasts. The antisense oligo treatment also significantly reduced the average depth of resorption pits created by rabbit osteoclasts under basal conditions. Calcitonin and alendondrate, significantly reduced resorption activity and PTP‐oc expression, and increased c‐Src PY527 with corresponding reduction in its PTK activity. The cellular PTP‐oc protein level correlated with the resorption activity. Among the various signaling proteins co‐immunoprecipitated with PTP‐oc, the resorption effectors caused corresponding changes in the tyrosyl phosphorylation level of only c‐Src. The GST–PTP‐oc fusion protein dephosphorylated PY‐527‐containing c‐Src peptide in time‐ and dose‐dependent manner in vitro. In summary, (1) PTP‐oc is regulated in part at transcriptional level, (2) upregulation of PTP‐oc in osteoclasts led to c‐Src activation, and (3) PY527 of c‐Src may be a cellular substrate of PTP‐oc. These findings are consistent with the hypothesis that PTP‐oc is a positive regulator of c‐Src in osteoclasts. J. Cell. Biochem. 97: 940–955, 2006. © 2005 Wiley‐Liss, Inc.
Cell cycle control in breast cancer cells
Authors: Caldon C. Elizabeth , Daly Roger J. , Sutherland Robert L. , Musgrove Elizabeth A.
Published: November 2005

In breast cancer, cyclins D1 and E and the cyclin‐dependent kinase inhibitors p21 (Waf1/Cip1)and p27 (Kip1) are important in cell‐cycle control and as potential oncogenes or tumor suppressor genes. They are regulated in breast cancer cells following mitogenic stimuli including activation of receptor tyrosine kinases and steroid hormone receptors, and their deregulation frequently impacts on breast cancer outcome, including response to therapy. The cyclin‐dependent kinase inhibitor p16 (INK4A) also has a critical role in transformation of mammary epithelial cells. In addition to their roles in cell cycle control, some of these molecules, particularly cyclin D1, have actions that are not mediated through regulation of cyclin‐dependent kinase activity but may be important for loss of proliferative control during mammary oncogenesis. © 2005 Wiley‐Liss, Inc.
The fiscal effects of aid in Ghana
Authors: Osei Robert , Morrissey Oliver , Lloyd Tim
Published: November 2005

An important feature of aid to developing countries is that it is given to the government. As a result, aid should be expected to affect fiscal behaviour, although theory and existing evidence is ambiguous regarding the nature of these effects. This paper applies techniques developed in the ‘macroeconometrics’ literature to estimate the dynamic linkages between aid and fiscal aggregates. Vector autoregressive methods are applied to 34 years of annual data in Ghana to model the effect of aid on fiscal behaviour. Results suggest that aid to Ghana has been associated with reduced domestic borrowing and increased tax effort, combining to increase public spending. This constructive use of aid to maintain fiscal balance is evident since the mid‐1980s, following Ghana's structural adjustment programme. The paper provides evidence that aid has been associated with improved fiscal performance in Ghana, implying that the aid has been used sensibly (at least in fiscal terms). Copyright © 2005 John Wiley & Sons, Ltd.
Glycosylation site analysis of human alpha‐1‐acid glycoprotein (AGP) by capillary liquid chromatography—electrospray mass spectrometry
Authors: Imre Tímea , Schlosser Gitta , Pocsfalvi Gabriella , Siciliano Rosa , Molnár‐Szöllősi Éva , Kremmer Tibor , Malorni Antonio , Vékey Károly
Published: November 2005

A new anionic surfactant (RapiGest SF) was successfully used for site‐specific analysis of glycosylation in human alpha‐1‐acid glycoprotein (AGP). By means of this analytical approach combined with capillary HPLC‐mass spectrometry (and tandem mass spectrometry), the N‐linked glycosylation pattern of AGP was explored. On the basis of mass matching and MS/MS experiments ca 80 different AGP‐derived glycopeptides were identified. Glycosylation shows a markedly different pattern for the various glycosylation sites. At sites I and II, triantennary complex‐type oligosaccharides predominate and at sites III, IV and V, tetra‐antennary complex‐type oligosaccharides predominate. Sites IV and V show the presence of additional N‐acetyl lactosamine (Gal‐GlcNAc) units (even higher degree of branching and/or longer antennae are also present). Copyright © 2005 John Wiley & Sons, Ltd.
Neuroprotective effects of GluR6 antisense oligodeoxynucleotides on transient brain ischemia/reperfusion‐induced neuronal death in rat hippocampal CA1 region
Authors: Pei Dong‐Sheng , Guan Qiu‐Hua , Sun Ya‐Feng , Zhang Qing‐Xiu , Xu Tian‐Le , Zhang Guang‐Yi
Published: November 2005

To investigate whether the kainate (KA) receptors subunit GluR6 is involved in the neuronal cell death induced by cerebral ischemia followed by reperfusion, the antisense oligodeoxynucleotides (ODNs) of GluR6 were used to suppress the expression of GluR6 by intracerebroventricular infusion once per day for 3 days before ischemia. Transient brain ischemia was induced by four‐vessel occlusion in Sprague‐Dawley rats. The effects of GluR6 antisense ODNs on the phosphorylation of MLK3 and JNK and the interactions of MLK3 and PSD‐95 with GluR6 were examined by immunoprecipitation and immunoblotting. Our results show that GluR6 antisense ODNs can knock down the expression of GluR6 and suppress the assembly of the GluR6·PSD‐95·MLK3 signaling module and, therefore, inhibit JNK activation and phosphoralation of c‐jun. On the other hand, the GluR6 antisense ODNs also show a protective role against neuronal cell death induced by cerebral ischemia/reperfusion. Administration of GluR6 antisense ODNs once per day for 3 days before cerebral ischemia significantly decreased neuronal degeneration. In conclusion, our results demonstrate that kainate receptor subunit GluR6 plays an important role in neuronal death induced by cerebral ischemia followed by reperfusion. © 2005 Wiley‐Liss, Inc.
Differential role of tumor necrosis factor receptors in mouse brain inflammatory responses in cryolesion brain injury
Authors: Quintana Albert , Giralt Mercedes , Rojas Santiago , Penkowa Milena , Campbell Iain L. , Hidalgo Juan , Molinero Amalia
Published: November 2005

Tumor necrosis factor‐α (TNF‐α) is one of the mediators dramatically increased after traumatic brain injury that leads to the activation, proliferation, and hypertrophy of mononuclear, phagocytic cells and gliosis. Eventually, TNF‐α can induce both apoptosis and necrosis via intracellular signaling. This cytokine exerts its functions via interaction with two receptors: type‐1 receptor (TNFR1) and type‐2 receptor (TNFR2). In this work, the inflammatory response after a freeze injury (cryolesion) in the cortex was studied in wild‐type (WT) animals and in mice lacking TNFR1 (TNFR1 KO) or TNFR2 (TNFR2 KO). Lack of TNFR1, but not of TNFR2, significantly decreased the inflammatory response and tissue damage elicited by the cryolesion at both 3 and 7 days postlesion, with decreased gliosis, lower IL‐1β immunostaining, and a reduction of apoptosis markers. Cryolesion produced a clear induction of the proinflammatory cytokines interleukin (IL)‐1α, IL‐1β, IL‐6, and TNF‐α; this induction was significantly lower in the TNFR1 KO mice. Host response genes (ICAM‐1, A20, EB22/5, and GFAP) were also induced by the cryolesion, but to a lesser extent in TNFR1 KO mice. Lack of TNFR1 signaling also affected the expression of apoptosis/cell death‐related genes (Fas, Rip, p53), matrix metalloproteinases (MMP3, MMP9, MMP12), and their inhibitors (TIMP1), suggesting a role of TNFR1 in extracellular matrix remodeling after injury. However, GDNF, NGF, and BDNF expression were not affected by TNFR1 deficiency. Overall, these results suggest that TNFR1 is involved in the early establishment of the inflammatory response and that its deficiency causes a decreased inflammatory response and tissue damage following brain injury. © 2005 Wiley‐Liss, Inc.
The cytoplasmic tail of the α3integrin subunit promotes neurite outgrowth in PC12 cells
Authors: Mechai Nadja , Wenzel Markus , Koch Manuel , Lucka Lothar , Horstkorte Rüdiger , Reutter Werner , Danker Kerstin
Published: November 2005

Binding of integrins to proteins of the extracellular matrix (ECM) provides structural and signaling information for biological processes such as cell proliferation, migration, neurite outgrowth, and differentiation. Integrins represent a family of heterodimeric transmembrane cell surface receptors. Besides connecting the ECM with the cytoskeleton, integrins also induce various signaling pathways in response to ligand binding. Integrin ligation leads to cytoplasmic protein–protein interactions requiring both integrin cytoplasmic tails. These sequences are initiation points for focal adhesion formation and subsequent signal transduction cascades. In this study, we addressed the question of whether the short cytoplasmic tail of the α3integrin subunit of α3β1integrin is required for α3β1integrin‐dependent processes. For this purpose, cDNA representing the extracellular and transmembrane domain of the interleukin 2 receptor (IL2R) α subunit and the cytoplasmic sequence of the α3integrin subunit was transfected into PC12 cells. Autonomous expression of the cytoplasmic α3tail does not affect attachment but leads to inhibition of neuronal differentiation on laminin 5. This indicates that the cytoplasmic α3sequence is not required for cell attachment but is necessary for long‐term adhesion and for the reorganization of the cytoskeleton that precedes neuronal differentiation. Inhibition of neurite outgrowth by chimeric IL2R‐α3can be rescued by treatment of transfected cells with the pharmacological inhibitor Y27632, which inhibits the RhoA downstream effector Rho kinase α. © 2005 Wiley‐Liss, Inc.
Complete suppression of paroxysmal nonkinesigenic dyskinesia by globus pallidus internus pallidal stimulation
Authors: Yamada Kazumichi , Goto Satoshi , Soyama Naohiro , Shimoda Osamu , Kudo Mareina , Kuratsu Jun‐Ichi , Murase Nagako , Kaji Ryuji
Published: November 2005

Stereotactic functional surgery is being explored as potential therapies for medically intractable paroxysmal dyskinesias (PxD). We report on a 59‐year‐old man in whom stimulation of globus pallidus internus produced immediate and sustained relief of paroxysmal non‐kinesigenic dyskinesia secondary to a rotator cuff tears on the left shoulder. Our finding strongly suggests that altered function of neuronal circuits of the basal ganglia underlies the manifestation of PxD. © 2005 Movement Disorder Society
Zero resonances in local perturbations of parallel‐plane waveguides
Authors: Werner P.
Published: November 2005

In a joint paper with K. Morgenröther [9] we have studied the propagation of scalar waves in domains of the type Ω = Ωo−B̄ with Ωo:=ℝ2 × (0, 1), where B is a smooth bounded domain with B̄ ⊏ Ωo. In particular, we have shown that the solution of Neumann's initial and boundary value problem for the wave equation with time‐independent right‐hand side ƒ increases with a logarithmic rate as t → ∞ if the integral over ƒ does not vanish. The main purpose of the present paper is to extend this result to arbitrary smooth local perturbations of Ωo.
Time‐invariant uniqueness for reacting viscous fluids near chemical equilibrium
Authors: Morro A. , Straughan B.
Published: November 2005

A system of equations is investigated which models a reacting mixture of viscous fluids acted upon by an external body force. Through logarithmic convexity arguments the solution is shown to be unique when either the initial or the final data are given.
On a contact problem for a system of parabolic equations in the thermal conductivity of electric machines: I
Authors: Małecki Romuald , Olszewski Paweł , Urbanowicz Jacek , Urbańki Wojciech
Published: November 2005

Thermal phenomena arising in some electric motors are described (physical model) and an adequate mathematical model is constructed. The model, in the form of a contact problem, is then approximated in a numerical way. The stability of the difference scheme obtained is investigated.
Long‐time behaviours of the spatially uniform discrete nagumo model
Authors: Zhi‐xiong Chen , (Kuo Pen‐yu) Guo‐Ben‐Yu
Published: November 2005

In this paper a spatially uniform discrete Nagumo model is considered. The relation between the number and positions of period‐2 solutions, and the parameter and initial values are discovered. The long‐time behaviours of the solutions are discussed for different parameters and initial values.
A mathematical model for diffusion and exchange phenomena in ultra napkins
Authors: Weickert Joachim
Published: November 2005

The performance of napkins is nowadays improved substantially by embedding granules of a superabsorbent into the cellulose matrix. In this paper a continuous model for the liquid transport in such an “ultra napkin” is proposed. Its mean feature is a non‐linear diffusion equation strongly coupled with an ODE describing a reversible absorption process. An efficient numerical method based on a symmetrical time splitting and a finite difference scheme of ADI‐predictor‐corrector type has been developed to solve these equations in a three‐dimensional setting. Numerical results are presented that can be used to optimize the granule distribution.
Stabilization estimates for penetrative motions in porous media
Authors: Franchi Franca
Published: November 2005

The physical model for penetrative convection in porous media is here considered to study the effects of variation of the source parameters on the flow. In this note we study the continuous dependence upon the heat supply and the body force of the classical solutions to the initial‐boundary value problem of a heat conducting fluid through a porous solid, both for the (well‐posed) forward problem and for the (improperly posed) backward in time one. For the former problem we obtain a result of continuous dependence with respect to the L2 norm; while for the latter we prove a result of Hölder continuity in a suitably constrained class of solutions.
Polygonal interface problems for the biharmonic operator
Authors: Nicaise Serge
Published: November 2005

We study some boundary value problems on two‐dimensional polygonal topological networks, where on each face, the considered operator is the biharmonic operator. The transmission conditions we impose along the edges are inspired by the models introduced by H. Le Dret [13] and Destuynder and Nevers [9]. The boundary conditions on the external edges are the classical ones. This class of problem contains the boundary value problems for the biharmonic equation in a plane polygon (see [3, 11, 12, 18]). Conforming to the classical results cited above, we prove that the weak solution of our problem admits a decomposition into a regular part and a singular part, the latter being a linear combination of singular functions depending on the domain and the considered boundary value problem. Finally, we give the exact formula for the coefficients of these singularities.
Landesman–Lazer resonance problems and saddle point methods
Authors: Schechter Martin
Published: November 2005

We show how saddle point techniques can be used to obtain new results for general resonance problems of the type considered by Landesman and Lazer.
General interface problems—I
Authors: Nicaise Serge , Sändig Anna‐Margarete
Published: November 2005

We study transmission problems for elliptic operators of order 2m with general boundary and interface conditions, introducing new covering conditions. This allows to prove solvability, regularity and asymptotics of solutions in weighted Sobolev spaces. We give some numerical examples for the location of the singular exponents.
A tracking method for gas flow into vacuum based on the vacuum Riemann problem
Authors: Munz C.‐D.
Published: November 2005

In this paper, a tracking method is proposed for the expansion of gas flow into vacuum which may be combined with numerical methods for the equations of gas dynamics, the Euler equations. This tracking prevents the difficulties of the numerical approximation introduced by the vacuum as a region where the Euler equations are not valid due to the failure of the continuum assumption. The tracking algorithm is based on the exact or an approximate solution of the vacuum Riemann problem. This is the initial value problem with two constant states, one being the gas and the other the vacuum state, and a limit case of the usual Riemann problem. In this approach, the gas–vacuum boundary is sharply resolved within one mesh interval. For a test problem, the numerical results of gas flow into vacuum are presented which indicate that the gas vacuum boundary is captured very well.
Dynamical stability of an elastic column and the phenomenon of bifurcation
Authors: Furta Stanislav D.
Published: November 2005

The article studies the stability of rectilinear equilibrium shapes of a non‐linear elastic thin rod (column or Timoshenko's beam), the ends of which are pressed. Stability is studied by means of the Lyapunov direct method with respect to certain integral characteristics of the type of norms in Sobolev spaces. To obtain equations of motion, a model suggested in [16] is used. Furta [6] solved the problem of stability for all values of the parameter except bifurcational ones. When values of the system's parameter become bifurcational, the study of stability is more complicated already in a finite‐dimensional case. To solve a problem like that, one often has to use a procedure of solving the singularities described in [1], for example. In this paper a change of variables is made which, in fact, is the first step of the procedure mentioned. To prove instability, we use a Chetaev function which can be considered as an infinite‐dimensional analogue of functions suggested in [14, 9]. The article also investigates a linear problem on the stability of adjacent shapes of equilibrium when the parameter has supercritical values (post‐buckling).
Asymptotic behaviour of solutions to semilinear wave equations with initial data of slow decay
Authors: Kubo Hideo
Published: November 2005

Some useful and remarkable property are derived from a representation formula of a radially symmetric solution to the Cauchy problem for a homogeneous wave equation in odd space dimensions. These properties provide us with enough information to consider the semilinear case, namely, the associated integral equation with the problem will be considered on a weighted L∞‐space. This formulation enables us to deal with the problem for slowly decaying initial data.
Generalized spherical harmonics and exterior differentiation in weighted sobolev spaces
Authors: Weck Norbert , Witsch Karl J.
Published: November 2005

We generalize spherical harmonics expansions of scalar functions to expansions of alternating differential forms (‘q‐forms’). To this end we develop a calculus for the use of spherical co‐ordinates for q‐forms and determine the eigen‐q‐forms of the Beltrami‐operator on SN−1 which replace the classical spherical harmonics. We characterize and classify homogeneous q‐forms u which satisfy Δu = 0 on ℝN∖︁{0} and determine Fredholm properties, kernel and range of the exterior derivative d acting in weighted Lp‐spaces of q‐forms (generalizing results of McOwen for the scalar Laplacian). These techniques and results are necessary prerequisites for the discussion of the low‐frequency behaviour in exterior boundary value problems for systems occurring in electromagnetism and isotropic elasticity.
An approximate Gidas–Ni–Nirenberg theorem
Authors: Rosset Edi
Published: November 2005

We study positive solutions u to Δu + f(u) = 0 in Ω, u = 0 on ∂Ω, and we address the following question: If Ω is a small perturbation of a ball, is u a small perturbation of a radially symmetric function? We prove two theorems which give an affirmative answer under different assumptions on the non‐linearity f and on the topologies in which perturbations are considered.
The norm and the essential norm of the double layer elastic and hydrodynamic potentials in the space of continuous functions
Authors: Kresin Gershon I. , Maz'ya Vladimir G.
Published: November 2005

We study a class of matrix integral operators which appear as limit values of the double layer potentials. We find general representations for the norms and for the essential norms of such operators in the space of continuous vector‐valued functions.

These representations are specified for boundary integral operators of linear isotropic elasticity theory and hydrodynamics of viscous incompressible fluid under the assumption that there is an angle point on the boundary of a plane domain and a conic point or an edge on the boundary of a three‐dimensional domain.
Initial‐boundary value problems in linear viscoelasticity on the half‐space
Authors: Mark J. , Meister E.
Published: November 2005

After deriving the linear hereditary constitutive laws for viscoelasticity, deducing frequency representation and the correspondence principle to linear elastodynamics the weak form of the equations of motion and their decomposition into pseudo‐wave equations are stated. Applying a Laplace transform in the time domain the Green's tensor is constructed by means of a spatial distributional Fourier transform. A detailed discussion of the four main initial‐boundary value problems with prescribed displacement and traction components on the plane {x3 = 0} leads to half‐space representations by inverse Fourier integrals. Finally some asymptotic behaviour of the solution in the original time domain is deduced.
An Optimal successive overrelaxtion technique for solving second order finite difference equations for triangular meshes
Authors: Tomlin Geoffrey R.
Published: November 2005

A finite difference method for analyzing two‐dimensional steady‐state potential flow in a zoned anisotropic material is described.

A triangular mesh is used is as to avoid difficulties often occurring in the more familiar rectangular mesh where fractional mesh spaces exist at irregular boundaries. The system of finite difference equations based on the triangular mesh is assembled in a form such that the coefficient matrix is 3‐cylic and consistently ordered.1, 2 This enables the optimum accelerating factor for successive overrelaxation to be closely estimated. Since the rate of convergence to the solution, and consequently the efficiency of the method, increases rapidly as the accelerating factor tends towards its optimum value, close determination of the optimum is important. The method is particularly suitable for problems having large numbers of nodes.

Examples of the method on specific problems are given. The solution accuracy is assessed and has been found acceptable.
A finite element solution of coupled electrokinetic and hydrodynamic flow in porous media
Authors: Lewis R. W. , Garner R. W.
Published: November 2005

The finite element method is applied to the solution f seepage problems where both electrokinetic and hydrodynamic forces occur. The resulting system of coupled equations is used to solve both the steady state and transient conditions in a one‐dimensional system and compared with the theoretical result. An analysis is then made of a more complex two‐dimensional problem where the application of electro‐osmosis may be used successfully to prevent piping.
The collapse load of reinforced concrete plate
Authors: Chan H. S. Y.
Published: November 2005

Numerical calculation of the collapse load of a reinforced concrete plate is considered. Mathematical programming formulations are derived by using finite element representation. The plate is assumed to obey the square yield criteria. It is shown that good lower bound solutions can be obtained on a systematic basis. Upper bound solutions are approximated result of yield‐line theory. An example of the square built‐in plate loaded uniformly is given.
Dual analysis for heat conduction problems by finite elements
Authors: De Veubeke B. M. Fraeijs , Hugge M. A.
Published: November 2005

An alternative approach to the usual finite element treatment of steady‐state temperature problems is presented, using approximations for the field of the dual variables.

The appropriate extremum principle is established and its minimization is discussed in connection with a plane triangular finite element process. Original heat flow elements are derived: in conjunction with temperature elements, they enable dual analysis of a given structure and an important estimate of the convergence to the true solution by upper and lower bounds to the dissipation function, as illustrated by means of several examples.
A new formulation of the plastic design problem for plane frames
Authors: Davies J. M.
Published: November 2005

Using a parametrie representation, it was proved in 19591 that the static and kinematic approaches to the plastic collapse problem are dual linear programming problems. In this paper, the generalized parameters used previously are given physical meaning and shown to be readily programmed for computer application. One important advantage of the method is that the equations can be written in general terms such that no assumptions regarding the structural from need to be built into the program. The application is extended to the more general problem of automatic plastic design and it is shown that the inclusion of a serviceability constraint (e.g. no plastic hinges at a given load factor) is trivial in this formulation. The difficult problem of several loading cases is shown to be readily, treated by designing for a given load factor for shakedown rather than plastic collapse. Thought this latter facility, by its dependence on elastic behavior, requires iteration of the stiffness of the structure, repaid convergence appears to be generally obtained. Finally a method is suggested whereby an adequate allowance for frame instability may be made without destroying the linearity of the equations. Thought the equations, as developed, have application to steel framed structures in mind, the extension to the limit design of reinforced concrete structures appears to present no addition complications.
Stochastic shakedown analysis of concrete slabs
Authors: Muspratt M. A.
Published: November 2005

A method of lower bound plastic analysis of axisymmetric slabs for shakedown conditions is described which permits inclusion of stochastic parameters. All solutions are obtained numerically using a mathematical programming approach. Results are for concreteslabs.
Computational procedures for the maximum likelihood parameters of the gamma and beta distributions
Authors: Philips D. T. , Beightler C. S.
Published: November 2005

A computational procedure is presented for calculating the maximum likelihood sampled parameters for the gamma and beta distributions. The procedure employed is both computationally efficient and easy to use. In order to facilitate immediate application, a self‐contained FORTRAN IV computer code has been included to carry out the necessary operations.
Free vibration analysis of spinning structural systems
Authors: Gupta K. K.
Published: November 2005

This article presents an efficient digital computer procedure, along with the complete listing of the associated computer program, which may be conveniently utilized for the accurate solution of a wide range of practical eigenvalue problems. Important applications of the present work are envisaged in the natural frequency analysis of spinning structures discretized by the finite element technique, and in the determination of transfer function associated with the dynamic blocks of control systems of spacecraft utilizing gas jets or reaction wheels for attitude control, as well as of spin‐stabilized and dual‐spin‐stabilized satellites.

The validity of the Sturm sequence property is first established for the related matrix formulation involving Hermitian and real symmetric, positive‐definite matrices, both being usually of highly banded configuration. A numerically stable algorithm based on the Sturm sequence method is then developed which fully exploits the banded form of the associated matrices. The related computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be extremely fast and economical in comparison to other existing methods of such analysis. Numerical results are presented for spinning bent cantilever beam and the solar arrays of SKYLAB, the earth‐orbiting space station proposed by NASA.
The treatment of natural boundary conditions in the finite element and finite difference methods
Authors: Croll J. G. A.
Published: November 2005

To isolate the relative accuracy in the numerical approximation of the natural boundary conditions, a plane‐ stress example is presented for which the field equations using finite element and finite difference methods are identical. For this example, and by implication a wider class of problem, it is demonstrated that by using conventional practice in both methods the implicit representation of the natural boundary conditions in the finite element gives rise to a lower numerical accuracy than that in the less convenient explicit satisfaction of these boundary conditions in finite difference method.