bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical solutions of Euler equations by using a new flux vector splitting scheme
Authors: Zha G‐C. , Bilgen E. 
Published: November 2005

AbstractA new flux vector splitting scheme has been suggested in this paper. This scheme uses the velocity component normal to the volume interface as the characteristic speed and yields the vanishing individual mass flux at the stagnation. The numerical dissipation for the mass and momentum equations also vanishes with the Mach number approaching zero. One of the diffusive terms of the energy equation does not vanish. But the low numerical diffusion for viscous flows may be ensured by using higher‐order differencing. The scheme is very simple and easy to be implemented. The scheme has been applied to solve the one dimensional (1D) and multidimensional Euler equations. The solutions are monotone and the normal shock wave profiles are crisp. For a 1D shock tube problem with the shock and the contact discontinuities, the present scheme and Roe scheme give very similar results, which are the best compared with those from Van Leer scheme and Liou–Steffen's advection upstream splitting method (AUSM) scheme. For the multidimensional transonic flows, the sharp monotone normal shock wave profiles with mostly one transition zone are obtained. The results are compared with those from Van Leer scheme, AUSM and also with the experiment.
A monotone streamline upwind method for quadratic finite elements
Authors: Hill D. L. , Baskharone E. A. 
Published: November 2005

AbstractA direct streamline upwind method has been developed for convection‐dominated flow problems utilizing quadratic elements. The approach presented retains the curve‐sidedness feature offered by these elements. This facilitates the use of boundary conforming elements in domains that possess extreme curvature such as turbomachinery bladed components, for which the method is particularly suited. Three test cases are solved to evaluate the stability and diffusive characteristics of the numerical solution. The results presented clearly demonstrate that the proposed method does not exhibit any non‐physical spatial oscillations, nor does it suffer from the traditional problem of excessive numerical diffusion.
Extension of multigrid methodology to supersonic/hypersonic 3‐D viscous flows
Authors: Vatsa Veer N. , Turkel Eli , Abolhassani J. S. 
Published: November 2005

AbstractA multigrid acceleration technique developed for solving the three‐dimensional Navier–Stokes equations for subsonic/transonic flows has been extended to supersonic/hypersonic flows. An explicit multistage Runge–Kutta type of time‐stepping scheme is used as the basic algorithm in conjunction with the multigrid scheme. Solutions have been obtained for a blunt conical frustum at Mach 6 to demonstrate the applicability of the multigrid scheme to high‐speed flows. Computations have also been performed for a generic High‐Speed Civil Transport configuration designed to cruise at Mach 3. These solutions demonstrate both the efficiency and accuracy of the present scheme for computing high‐speed viscous flows over configurations of practical interest.
Gradient method of optimal control applied to the operation of a dam water gate
Authors: Kawahara Mutsuto , Shimada Yoshiro 
Published: November 2005

AbstractAn extension of the authors' previous methods is presented for the optimal control of flood propagation via a dam gate, based on a combination of the finite element and gradient methods. It is assumed in previous papers that the control duration is the same as the duration of the flood. However, the duration of the control does not necessarily coincide with that of the flood flow. To overcome this difficulty, the gradient method is applied to solve the free terminal time‐fixed terminal condition problem. It is shown that the water elevation can be controlled exactly the same as with the previously presented method. It is also shown that the computation can be terminated at a far shorter time than the terminal time of the flood.
Numerical investigation of leading edge separated flow over cranked wings using a vortex lattice model
Authors: Bandyopadhyay G. 
Published: November 2005

AbstractNumerical models based on the vortex lattice concept using free vortex lines have been developed for the calculation of separated flow about cranked wings. Various separated flow models are developed assuming the flow to be separated along the leading edges of (i) the inner wing, (ii) the entire wing and (iii) the inner wing and the outboard part of the outer wing. To illustrate the effects of separation, attached flow solutions are also obtained. Results are compared with available experimental results. Agreement with separated flow solutions is usually good except at very high incidence.
Upstream monotonic interpolation for scalar transport with application to complex turbulent flows
Authors: Lien F. S. , Leschziner M. A. 
Published: November 2005

AbstractA new monotonic scheme for the approximation of steady scalar transport is formulated and implemented within a collocated finite‐volume/pressure‐correction algorithm for general turbulent flows in complex geometries. The scheme is essentially a monotonic implementation of the quadratic QUICK interpolation and uses a continuous and compact limiter to secure monotonicity. The principal purpose is to allow an accurate and fully bounded, hence stable, approximation of turbulence convection in the context of two‐equation eddy viscosity and Reynolds stress transport modelling of two‐ and three‐dimensional flows, both subsonic and transonic. Among other benefits, this capability permits an assessment to be made of the adequacy of approximating turbulence convection with first‐order upwind schemes in conjunction with higher‐order formulations for mean‐flow properties—a widespread practice. The performance characteristics of the bounded scheme are illustrated by reference to computations for scalar transport, for a transonic flow in a Laval nozzle, for one separated laminar flow and for two separated turbulent flows computed with a non‐linear RNG model and full Reynolds stress closure.
A data‐parallel approach to multiblock flow computations
Authors: Sawley M. L. , Tegnér J. K. 
Published: November 2005

AbstractMultiblock methods are often employed to compute flows in complex geometries. While such methods lend themselves in a natural way to coarse‐grain parallel processing by the distribution of different blocks to different processors, in some situations a fine‐grain data‐parallel implementation may be more appropriate. A study is presented of the resolution of the Euler equations for compressible flow on a block‐structured mesh, illustrating the advantages of the data‐parallel approach. Particular emphasis is placed on a dynamic block management strategy that allows computations to be undertaken only for blocks where useful work is to be performed. In addition, appropriate choices of initial and boundary conditions that enchance solution convergence are presented. Finally, code portability between five different massively parallel computer systems is examined and an analysis of the performance results obtained on different parallel systems is presented.
Mixed explicit/implicit time integration of coupled aeroelastic problems: Three‐field formulation, geometric conservation and distributed solution
Authors: Farhat Charbel , Lesoinne Michel , Maman Nathan 
Published: November 2005

AbstractA three‐field arbitrary Lagrangian‐Eulerian (ALE) finite element/voluem formulation for coupled transient aeroelastic problems is presented. The description includes a rigorous derivation of a geometric conservation law for flow problems with moving boundaries and unstructured deformable meshes. The solution of the coupled governing equations with a mixed explicit (fluid)/implicit (structure) staggered procedure is discussed with particular reference to accuracy, stability, distributed computing, I/O transfers, subcycling and parallel processing. A general and flexible framework for implementing partitioned solution procedures for coupled aeroelastic problems on heterogeneous and/or parallel computational platforms is described. This framework and the explicit/implicit partitioned procedures are demonstrated with the numerical investigation on an iPSC‐860 massively parallel processor of the instability of flat panels with infinite aspect ratio in supersonic airstreams.
The parallel processing technique applied to the cellular automation method in fluid dynamics simulations
Authors: Inoue Yukihiko , Katsuragi Kazuyuki , Ukai Osamu , Adachi Takeshi 
Published: November 2005

AbstractThis paper describes an efficient parallel algorithm of the cellular automaton (CA) method for microscopic fluid dynamics simulations. The CA method is parallelized with so‐called multispin coding and with one‐dimensional domain decomposition. The parallel CA method has a constant computational load balance and small data transfer between only nearby domains. We have applied the parallel CA method to a large‐scale Poiseuille flow simulation and an immiscible two‐phase flow simulation on a Fujitsu AP1000 with 64 processors.
Three‐step explicit finite element computation of shallow water flows on a massively parallel computer
Authors: Kashiyama Kazuo , Ito Hanae , Behr Marek , Tezduyar Tayfun 
Published: November 2005

AbstractMassively parallel finite element strategies for large‐scale computations of shallow water flows and contaminant transport are presented. The finite element discretizations, carried out on unstructured grids, are based on a three‐step explicit formulation both for the shallow water equations and for the advection‐diffusion equation governing the contaminant transport. Parallel implementations of these unstructured‐grid‐based formulations are carried out on the Army High Performance Computing Research Center Connection Machine CM‐5. It is demonstrated with numerical examples that the strategies presented are applicable to large‐scale computations of various shallow water flow problems.
Analysis of shear layers based on the lattice gas model
Authors: Yuasa Atsushi , Inamuro Takaji , Adachi Takeshi 
Published: November 2005

AbstractThe ‘two‐colour lattice gas model’ is applied to the analysis of shear layers between two parallel flows with different velocities U1 and U2. Two cases, (a) U1 = 0.4, U2 = 0.2 and (b) U1 = 0.4, U2 = 0.0, are calculated and compared with the theoretical solutions. We obtain good agreement between theory and calculations in the velocity profiles of the shear layers. It is found that this model can simulate complicated physical phenomena of shear layers at the microscopic level.
New numerical schemes based on a criterion for constructing essentially stable and accurate numerical schemes for convection‐dominated equations
Authors: Sakai Katsuhiro 
Published: November 2005

AbstractIn order to obtain stable and accurate numerical solutions for the convection‐dominated steady transport equations, we propose a criterion for constructing numerical schemes for the convection term that the roots of the characteristic equation of the resulting difference equation have poles.By imposing this criterion on the difference coefficients of the convection term, we construct two numerical schemes for the convection‐dominated equations. One is based on polynomial differencing and the other on locally exact differencing.The former scheme coincides with the QUICK scheme when the mesh Reynolds number (Rm) is \documentclass{article}\pagestyle{empty}\begin{document}$\mathop \[{\textstyle{{\rm 8} \over {\rm 3}}}\] $\end{document}, which is the critical value for its stability, while it approaches the second‐order upwind scheme as Rm goes to infinity. Hence the former scheme interpolates a stable scheme between the QUICK scheme at Rm = \documentclass{article}\pagestyle{empty}\begin{document}$\mathop \[{\textstyle{{\rm 8} \over {\rm 3}}}\] $\end{document} and the second‐order upwind scheme at Rm = ∞. Numerical solutions with the present new schemes for the one‐dimensional, linear, steady convection‐diffusion equations showed good results.
Modified box schemes for pollutant transport in rivers with dead zones
Authors: Strauber Györgyi 
Published: November 2005

AbstractSeveral difference schemes approximating a mathematical model of river pollution are investigated and their truncation error, stability and monotonicity conditions are shown. Based on numerical experiments, the classical six‐point schemes and some new modified box schemes are compared. The latter proved to be not only faster but also more accurate for practically used step lengths.
Aid to Africa: an unfinished agenda
Authors: Addison Tony , Mavrotas George , McGillivray Mark 
Published: November 2005

AbstractThe Millennium Development Goals (MDGs) give aid to Africa a new emphasis. Yet aid flows to Africa have trended downward over the last decade, and as a consequence more Africans now live in poverty. This is especially true of Sub‐Saharan Africa. Any progress towards the main MDG target of halving the number of people living in poverty clearly requires more aid. It also requires a better understanding of what drives aid volumes to Africa and precisely how these flows impact on African economies. This paper examines trends in official aid to Africa, Sub‐Saharan Africa in particular, over the period 1960 to 2002, highlighting falls in aid since the early 1990s. It concludes with consideration of future challenges for aid to Africa. Copyright © 2005 John Wiley & Sons, Ltd.
The facial motor nucleus transcriptional program in response to peripheral nerve injury identifies Hn1 as a regeneration‐associated gene
Authors: Zujovic Violetta , Luo Defang , Baker Henry V. , Lopez M. Cecilia , Miller Kelly R. , Streit Wolfgang J. , Harrison Jeffrey K. 
Published: November 2005

AbstractFacial nerve axotomy (FNA) is a well‐established experimental model of motoneuron regeneration. After peripheral nerve axotomy, a sequence of events including glial activation and axonal regrowth leads to functional recovery of the afflicted pool of motoneurons. Using microarray analysis we identified an increase in the expression of 60 genes (at a false discovery rate of 0.1, genes were significant P < 0.004) within the facial nucleus as a consequence of nerve injury. In situ hybridization analysis validated the increased expression of many of these axotomy‐induced genes. One specific gene, encoding a unique primary amino acid sequence, termed hemopoietic‐ and neurologic‐expressed sequence‐1 (Hn1), was evaluated more extensively using several additional nerve injury paradigms. Hn1 mRNA was upregulated in injured facial motoneurons in both rats and mice. Sustained upregulation of Hn1 mRNA was evident after nerve resection whereas levels of Hn1 mRNA returned to baseline in animals subjected to nerve crush or nerve transection. Hn1 was also increased in the dorsal motor nucleus and the nucleus ambiguous after vagus nerve axotomy, another regeneration model. No upregulation of Hn1 expression was observed, however, in two nonregeneration models: FNA in newborn rats and rubrospinal tractotomy. Hn1 mRNA was ubiquitous in the developing central nervous system whereas its expression in adult brain was confined to neurons of the hippocampus, cortex and cerebellum. These findings identify Hn1 as a gene associated with nervous system development and nerve regeneration. © 2005 Wiley‐Liss, Inc.
Phosphodiesterase‐Iα/autotaxin (PD‐Iα/ATX): A multifunctional protein involved in central nervous system development and disease
Authors: Dennis Jameel , Nogaroli Luciana , Fuss Babette 
Published: November 2005

AbstractPhosphodiesterase‐Iα/autotaxin (PD‐Iα/ATX) was originally identified as a cell‐motility‐stimulating factor secreted by a variety of tumor cells. Thus, studies related to its potential functional roles have traditionally focused on tumorigenesis. PD‐Iα/ATX's catalytic activity, initially defined as nucleotide pyrophosphatase/phosphodiesterase, was soon recognized as being necessary for its tumor cell‐motility‐stimulating activity. However, only the discovery of PD‐Iα/ATX's identity with lysophospholipase D, an extracellular enzyme that converts lysophosphatidylcholine into lysophosphatidic acid (LPA) and potentially sphingosylphosphoryl choline into sphingosine 1‐phosphate (S1P), revealed the actual effectors responsible for PD‐Iα/ATX's ascribed motogenic functions, i.e., its catalytic products. PD‐Iα/ATX has also been detected during normal development in a number of tissues, in particular, the central nervous system (CNS), where expression levels are high. Similar to tumor cells, PD‐Iα/ATX‐expressing CNS cells secrete catalytically active PD‐Iα/ATX into the extracellular environment. Thus, it appears reasonable to assume that PD‐Iα/ATX's CNS‐related functions are mediated via lysophospholipid, LPA and potentially S1P, signaling. However, recent studies identified PD‐Iα/ATX as a matricellular protein involved in the modulation of oligodendrocyte–extracellular matrix interactions and oligodendrocyte remodeling. This property of PD‐Iα/ATX was found to be independent of its catalytic activity and to be mediated by a novel functionally active domain. These findings, therefore, uncover PD‐Iα/ATX, at least in the CNS, as a multifunctional protein able to induce complex signaling cascades via distinct structure–function domains. This Mini‐Review describes PD‐Iα/ATX's multifunctional roles in the CNS and discusses their potential contributions to CNS development and pathology. © 2005 Wiley‐Liss, Inc.
Nitrate in vegetables: toxicity, content, intake and EC regulation
Authors: Santamaria Pietro 
Published: November 2005

AbstractNitrate content is an important quality characteristic of vegetables. Vegetable nitrate content is of interest to governments and regulators owing to the possible implications for health and to check that controls on the content are effective. Nitrate itself is relatively non‐toxic but its metabolites may produce a number of health effects. Until recently nitrate was perceived as a purely harmful dietary component which causes infantile methaemoglobinaemia, carcinogenesis and possibly even teratogenesis. Recent research studies suggest that nitrate is actually a key part of our bodies' defences against gastroenteritis. In this review are reported: (1) vegetable classification as a function of nitrate accumulation; (2) vegetable contribution to the total dietary exposure of nitrate; (3) European Commission Regulation No. 563/2002 which sets limits for nitrate in lettuce and spinach; (4) the maximum levels set in some countries for beetroot, cabbage, carrot, celery, endive, Lamb's lettuce, potato, radish and rocket; (5) the results of surveys on the nitrate content of vegetables in Italy and other European countries. Copyright © 2005 Society of Chemical Industry
The Parkinson–Control study: A 1‐year randomized, double‐blind trial comparing piribedil (150 mg/day) with bromocriptine (25 mg/day) in early combination with levodopa in Parkinson's disease
Authors: Castro‐Caldas Alexandre , Delwaide Paul , Jost Wolfgang , Merello Marcelo , Williams Adrian , Lamberti Paolo , Aguilar Miguel , Del Signore Susanna , Cesaro Pierre 
Published: November 2005

AbstractDopamine agonists have been recommended as early treatment for Parkinson's disease (PD), alone or combined with levodopa. Piribedil is a non‐ergot selective D2/D3 agonist with α2 antagonist properties shown to be effective in the treatment of PD. This 12‐month international, randomized, double‐blind trial aimed to assess the efficacy of piribedil 150 mg versus bromocriptine 25 mg, in early combination with levodopa in Stage I to III PD patients. Motor efficacy was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS III, Items 18–31) as improvement from baseline. Response rate was defined as a 30% improvement. Among the 425 randomly assigned patients, 178 were also included in a substudy on cognitive follow‐up evaluated by a dysexecutive syndrome oriented battery. A relevant improvement in UPDRS III over the 12‐month study duration was observed both in the piribedil and bromocriptine groups (−7.9 ± 9.7 points from baseline versus −8.0 ± 9.5; not significant [n.s.]) with a response rate of 58.4% and 55.3% (n.s.), respectively. Piribedil and bromocriptine resulted in similar improvement on all UPDRS III subscores. Piribedil patients required less levodopa dose increase than those on bromocriptine. Cognitive performance remained generally unchanged in both groups, with a significant effect of piribedil limited to the Wisconsin Card Sorting Test. An overall good tolerability of piribedil was observed. Early combination of piribedil 150 mg with levodopa resulted in significant long‐term improvement of all motor symptoms in PD patients insufficiently controlled by levodopa alone. Taking into account both efficacy and acceptability in the long‐term, piribedil proved in this bromocriptine controlled study to be an effective and safe treatment for PD. © 2005 Movement Disorder Society
Asymptotic analysis of the quantum Liouville equation
Authors: Steinrück Herbert 
Published: November 2005

AbstractWe present an asymptotic analysis of the quantum Liouville equation with respect to the Planck's constant, which models the temporal evolution of the (quasi)distribution of an ensemble of electrons under the action of a potential. We consider two cases: firstly a smooth potential, and secondly a potential modelled by a δ‐distribution. In both cases the zeroth‐order term behaves classically. In the smooth case the classical Liouville equation is satisfied and in the case for the δ‐potential an interface condition is derived, so that everything is reflected at the potential barrier.
An optimal control problem for the Helmholtz equation in a stratified Shallow ocean
Authors: Xu Yongzhi 
Published: November 2005

AbstractIn this paper we shall consider a kind of optimal control of the Robin problem. First, we discuss the solvability of the Robin problem, which is not uniquely solvable in general. Then we find the representation of the far‐field pattern in terms of the minimal solution to an integral equation. Based on this representation, an optimization problem is discussed and a Galerkin scheme for the solution is presented.
Determination of an unknown function in a parabolic equation with an overspecified condition
Authors: Chadam John M. , Yin Hong‐Ming 
Published: November 2005

AbstractIn this paper we consider the inverse problems of identifying some space‐dependent unknown coefficients in parabolic equations subject to initial boundary value conditions along with an overspecified condition at the final time t = T. We use the overspecified information to transform the problems into non‐linear parabolic equations involving a functional of the solution with respect to the time variable. This transformation allows us to establish existence theorems for these inverse problems by employing the Schauder fixed‐point theorem.
Advective estimates
Authors: Lohéac Jean‐Pierre 
Published: November 2005

AbstractConsider the partial differential equation: wt + bw + a· ∇w = g in ℝn × [0, T] (x1 <0) and if the function a1 is positive, then, in the left half‐space, the solution w is an O (ν) for small Viscosity ν.