bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, Absorption, and Fluorescence‐Emission Properties of 1,3,6,8‐Tetraethynylpyrene and Its Derivatives
Authors: Venkataramana Gandikota , Sankararaman Sethuraman 
Published: August 2005

AbstractThe synthesis of several 1,3,6,8‐tetraethynylpyrene derivatives is reported. The effect of extended acetylenic conjugation on their absorption and fluorescence‐emission properties is studied. Significant bathochromic shifts of both the absorption and fluorescence emission bands are observed. These derivatives emit fluorescence in the visible (400–550 nm) region. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cyclooctyne and 4‐Cyclooctyn‐1‐ol – Versatile Building Blocks in Organic Synthesis
Authors: Heber Dieter , Rösner Peter , Tochtermann Werner 
Published: August 2005

AbstractThe readily available and highly reactive title compounds represent versatile building blocks in organic synthesis. Recent examples of 1,3‐dipolar cycloadditions and Diels–Alder reactions and their applications are described. This microreview is especially devoted to cycloadducts formed between1and2and furans, and their transformations to give a variety of different classes of compounds, including derivatives of natural products. Here the conversion of oxanorbornadienes into bridged oxepines plays an important role in many cases. Different routes to enantiomerically pure compounds are also presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Simplified stripping potentiometry methodology: Application to the determination of lead in wine
Authors: Jagner Daniel , Renman Lars , Wang Yudong 
Published: August 2005

AbstractWine samples (120 μL) were pipetted into a 480 μL matrix modifying solution in a disposable Eppendorff tube. The modifying solution was comprised of hydrochloric acid, Hg(II), Ca(II), Al(III), Mn(II), 10% v/v Triton X‐100, 25% v/v EtOH, and Bi(III) as an internal standard. The mixture was transferred to a novel sample rotation assembly, used in combination with a cylindrical combined glassy carbon working electrode and Ag/AgCl reference and counter electrodes, and analyzed for 3 minutes by means of stripping potentiometry (SP). The analytical procedure, including control of all instrumental parameters and evaluation of the results, was performed fully automated using a commercial stripping analyzer and accompanying software. Calibration was performed using two aqueous standards, and due to the use of the internal standard, the same calibration curve could be used indefinitely. The relative precision was estimated to 5% and the detection limit to 3 μ/L. Good agreement was obtained between the results obtained by the proposed method and those obtained by isotope dilution inductively coupled plasma‐mass spectrometry (ICP‐MS) in the analysis of four red and four white wine samples, ranging in lead concentration from 18 to 151 μg/L, with the maximum relative difference between the two techniques being 11.5%.
Oxidative behavior of the sulfonamidic diuretic bumetanide at carbon paste electrode
Authors: Legorburu María J. , Alonso Rosa M. , Jiménez Rosa M. 
Published: August 2005

AbstractThe oxidative behavior of the 3‐(aminosulfonyl)‐5‐(butylamino)‐4‐phenoxy‐benzoic acid, Bumetanide, was studied in hydroalcoholic media (9:91 MeOH:H2O, pH range 1–9) and in two different ionic media (KNO3 and KCl) at a carbon paste electrode. The oxidation process has been shown to be irreversible and predominantly diffusion‐controlled over the entire pH range and in both media. A voltammetric method was developed at pH = 2.5 (phosphate buffer) and 0.4 M KNO3 for the quantitative determination of Bumetanide. The peak current was linear with the Bumetanide concentration in the range 2.74 × 10−6 M‐2.74 × 10−5 M with a detection limit of 4.39 × 10−7 M (0.16 ppm) and a reproducibility (in terms of relative standard deviation) of 3.61 and 7.60% for 10 determinations of 1.25 × 10−5 M and 4.99 × 10−6 M concentrations, respectively. The method for Bumetanide was applied to assays of pharmaceuticals (Fordiuran, 1 mg) and urine.
Improved finite element forms for the shallow‐water wave equations
Authors: Williams R. T. , Zienkiewicz O. C. 
Published: August 2005

AbstractThis paper presents new finite element formulations of the shallow‐water wave equations which use different basis functions for the velocity and height fields. These arrangements are analysed with the Fourier transform technique which was developed by Schoenstadt,1 and they are also compared with other finite difference and finite element schemes. The new schemes are integrated in time for two initial states and compared with analytic solutions and numerical solutions from other schemes. The behaviour of the new forms is excellent and they are also convenient to apply in two dimensions with triangular elements.
Numerical solutions of Navier‐Stokes equations with an integrated compartment method (ICM)
Authors: Yeh Gour‐Tsyh 
Published: August 2005

AbstractThe most common numerical methods that are used by physical scientists to approximate partial differential equations employ finite differences and/or finite elements. In addition, compartment analyses have been adopted by ecological system analysts to simulate the evolution of processes governed by differential equations without spatial derivatives. An integrated compartment method (ICM) is proposed to combine the merits of these three numerical techniques. The basic procedures of the ICM are first to discretize the region of interest into compartments, then to apply three integral theorems of vectors to transform the volume integral to the surface integral, and finally to use interpolation to relate the interfacial values in terms of compartment values to close the system. These procedures are applied to the Navier‐Stokes equations to yield the computational algorithm from which computer programs can be coded. The computer code is designed to solve one‐, two‐, or three‐dimensional problems as desired. The program is applied to two simple cases: wake formation behind an obstacle in a channel and circulatory motion of a body of fluid in the square cavity. These preliminary applications have shown promising results.
Applicability of algebraic models based on unidirectional flow to duct flow with lateral motion
Authors: Naot D. , Rodi W. 
Published: August 2005

AbstractThe solution for the stress transport turbulence model equations for the situation where the flow is unidirectional is now commonly applied to flows with weak secondary currents in closed ducts, open channels, and rod bundles in nuclear reactor channels. Here, perturbations to the unidirectional flow solutions are studied by solving the exact equations using an iterative procedure. Now the equations also contain the small lateral velocity gradients formerly neglected. The applicability as well as the limitation of the use of the unidirectional flow turbulence model for the description of channel flow with lateral motion are discussed. Modifications for weak lateral motion are suggested.
Numerical calculation of transitional boundary layers
Authors: Arad E. , Berger M. , Israeli M. , Wolfshtein M. 
Published: August 2005

AbstractA computational procedure for compressible axisymmetric boundary layers, on bodies of revolution, in transition from laminar to turbulent flow, is introduced. The procedure is an extension of a former method, due to Patankar and Spalding.The flow field is computed by solution of four simultaneous equations for the momentum, the thermal energy, the turbulence energy amplitude and the turbulent scale.The results show good agreement with existing theoretical and experimental data.
Consistent vs. reduced integration penalty methods for incompressible media using several old and new elements
Authors: Engelman M. S. , Sani R. L. , Gresho P. M. , Bercovier M. 
Published: August 2005

AbstractThe frequently used reduced integration method for solving incompressible flow problems ‘a la penalty’ is critically examined vis‐a‐vis the consistent penalty method. For the limited number of quadrilateral and hexahedral elements studied, it is shown that the former method is only equivalent to the latter in certain special cases. In the general case, the consistent penalty method is shown to be more accurate. Finally, we demonstrate significant advantages of a new element, employing biquadratic (2‐D) or triquadratic (3‐D) velocity and linear pressure over that using the same velocity but employing bilinear (2‐D) or trilinear (3‐D) pressure approximation.
Numerical solution of free surface, porous flow problems
Authors: Casulli V. , Greenspan D. 
Published: August 2005

AbstractAn inexpensive, finite difference numerical method is developed for the approximate solution of general, free surface, porous flow problems. The method is so designed that the required numerical boundary conditions coincide exactly with the required physical boundary conditions. In the present paper, application is made to prototype, steady state, dam flow problems.
Utilization of the method of characteristics to solve accurately two‐dimensional transport problems by finite elements
Authors: Varoḡlu Erol , Finn W. D. Liam 
Published: August 2005

AbstractA new finite element method is presented for the solution of two‐dimensional transport problems. The method is based on a weighted residual formulation in which the method of characteristics is combined with the finite element method. This is achieved by orienting sides of the space‐time elements joining the nodes at subsequent time levels along the characteristics of the pure advection equation associated with the transport problem. The method is capable of solving numerically the advection‐‐diffusion equation without generating oscillations or numerical diffusion for the whole spectrum of dispersion from diffusion only through mixed dispersion to pure convection.The utility and accuracy of the method are demonstrated by a number of examples in two space dimensions and a comparison of the numerical results with the exact solution is presented in one case. A very favourable feature of the method is the capability of solving accurately advection dominated transport problems with very large time steps for which the Courant number is well over one.
Analysis of two‐dimensional, finite amplitude wave propagation by time marching methods
Authors: Parker R. , James M. N. 
Published: August 2005

AbstractTwo‐dimensional, finite‐amplitude wave propagation in an inviscid, subsonic, perfect gas medium is analysed by explicit finite‐difference methods. A two‐step, Lax‐Wendroff method and the single‐step, Lax‐Friedrichs method are used. A prescribed propagating velocity or pressure disturbance is applied along a single row of grid points normal to the stream direction and results in a 'forced' outflow boundary. The inflow boundary is placed far from outflow by utilizing a streamwise expanding grid and uniform inflow is imposed. Side boundaries are spatially periodic. The numerical solutions are compared with analytical small‐perturbation solutions; higher‐order effects arising from non‐linearities are revealed by Fourier analysis. Solutions which closely approached a periodic state were obtained. The Lax‐Wendroff method combined with the expanding grid is shown to be accurate and stable, the Lax‐Friedrichs scheme produced highly damped solutions.
Numerical solution of a first‐order conservation equation by a least square method
Authors: Chattot J. J. , Guiu‐Roux J. , Lamine J. 
Published: August 2005

AbstractLeast square methods have been frequently used to solve fluid mechanics problems. Their specific usefulness is emphasized for the solution of a first‐order conservation equation. On the one hand, the least square formulation embeds the first‐order problem into equivalent second‐order problem, better adapted to discretization techniques due to symmetry and positive‐definiteness of the associated matrix. On the other hand, the introduction of a least square functional is convenient for finite element applications.This approach is applied to the model problem of the conservation of mass (the unknown is the density ρ) in a nozzle with a specified velocity field (u, v), possibly including jumps along lines simulating shock waves. This represent a preliminary study towards the solution of the steady Euler equations.A finite difference and a finite element method are presented. The choice of the finite difference scheme and of a continuous finite element representation for the groups of variables (ρu, ρv) is discussed in terms of conservation of mass flux. Results obtained with both methods are compared in two numerical tests with the same mesh system.
A transonic quasi‐3D analysis for gas turbine engines including split‐flow capability for turbofans
Authors: Habashi W. G. , Youngson G. G. 
Published: August 2005

AbstractA numerical approximation is taken to the solution of the complex flows existing in gas turbine engines with transonic blading. The quasi‐3D approach decouples the problem into through‐flow and blade‐to‐blade solutions. An industrially practical finite element through‐flow solution is developed and for blade‐to‐blade solutions a transonic finite areas method is utilized. The finite element code developed is capable of operating in an analysis or a design mode. In both modes a dynamic relaxation factor is employed and considerable reduction in solution time can be achieved. Comparisons to streamline curvature methods are carried out for simple analytical and complex industrial problems.
A finite element method for high Reynolds number viscous fluid flow using two step explicit scheme
Authors: Kawahara Mutsuto , Hirano Hirokazu 
Published: August 2005

AbstractThis paper presents the finite element method for the analysis of unsteady viscous flow of fluid at high Reynolds numbers. The method is based on the explicit numerical integration scheme in time and uses three node triangular finite elements. For the convenience of the formulation, slight compressibility is considered. For the explicit scheme, the selective lumping two step scheme has been successfully employed. Vortex shedding behind a cylinder has been computed and compared with the conventional experimental results. The results agree favourably when both schemes are compared.
The solution of a convection–diffusion–reaction equation arising from cathodic reduction in a pulsating crack
Authors: Warren M. D. 
Published: August 2005

AbstractThis paper derives the convection–diffusion‐reaction equation governing the reaction between the dissolved oxygen in sea‐water and the steel walls of a pulsating crack. By the neglect of the diffusion term it is shown that an exact solution of the convection‐reaction equation can be obtained. A numerical method for the solution of the complete convection–diffusion‐reaction equation is derived by the use of finite differences. The numerical computation of the initial transient and the final periodic steady‐state values is also discussed.
Natural convection in a square cavity: A comparison exercise
Authors: De Vahl Davis G. , Jones I. P. 
Published: August 2005

AbstractA number of contributed solutions to the problem of laminar natural convection in a square cavity have been compared with what is regarded as a solution of high accuracy. The purposes of this exercise have been to confirm the accuracy of the bench mark solution and to provide a basis for the assessment of the various methods and computer codes used to obtain the contributed solutions.
OPtimum design for potential flows
Authors: Angrand F. 
Published: August 2005

AbstractDescribed in this paper is a methodology for solving a particular class of optimum design problems in Fluid Mechanics, namely optimum design problems for aerofoils when the corresponding fluid flow is potential. The methods described in this paper operate directly in the physical space, and take advantage of the variational formulation of the partial differential equation modelling the flow. The techniques of optimal control, optimization and the finite element method are used. Numerical examples are also given.
A brief note on upwind collocation
Authors: Dougherty D. E. , Pinder G. F. 
Published: August 2005

AbstractUpwind collocation on Hermite cubics is compared to orthogonal collocation with respect to effective diffusion. The one‐dimensional constant coefficient advection‐diffusion equation is employed to this end. The effective diffusion coefficient is determined exactly and is found to be dependent on the nodal solution values. The effective diffusion coefficients of three other upwinding schemes are also presented. Upwind collocation is found to have an effective diffusion coefficient like other upwinding schemes plus an extra term which may enhance or reduce the non‐advective flux, depending on the problem solution and point location within the domain.
The effect of the choice of the reference pressure location in numerical modelling of incompressible flow
Authors: Jackson C. P. 
Published: August 2005

AbstractThe discontinuity of a finite‐element pressure field that is sometimes present in the neighbourhood of the pressure‐specification‐point is shown to arise either from round‐off, or from mistakes in modelling. The implications of this are considered. In particular it restricts grid refinement near the pressure‐specification‐point. The analysis can be extended to finite‐difference calculations, and to other fields governed by equations similar to Poisson's equation.
Boundary integral equation method for some Stokes problems
Authors: Tözeren Hüsnü 
Published: August 2005

AbstractThe boundary integral equation method is a numerical technique extensively applied in the solution of boundary value problems from many different engineering fields. The starting point of the method is the formulation of an integral equation which gives the variable at any point in terms of single and double layer potentials whose densities are the values of the variable and its derivatives on the boundary. The method consists of the numerical solution of this integral equation when the field point is taken to lie on the boundary. The present paper extends the formulation of the method to Stokes flows of a collection of particles in infinite circular cylinders. This is achieved by developing matrix Green's functions for Stokes flows in cylindrical boundaries. The results are found to be in good agreement with the results of Wang and Skalak1 and Tözeren.3
Finite element simulation of dip coating, II: Non‐Newtonian fluids
Authors: Tanguy P. , Fortin M. , Choplin L. 
Published: August 2005

AbstractWe apply in this paper the augmented Lagrangian method to the study of various non‐Newtonian fluid flow problems, and in particular the dip coating process. We only present in this second part the treatment specific to the non‐linearities involved in the constitutive equations, the first part having largely been concerned with the general description of the approximation used.Two rheological models illustrating different rheological behaviours are used to simulate dip coating process: the Carreau‐A model for shear‐thinning properties of the viscosity and a truncated second‐order model for a Newtonian behaviour in viscosity with elastic properties.Numerical predictions show a very good agreement with experimental data for the second‐order model. The discrepancy observed in the other case can be explained qualitatively by the elastic properties exhibited by the shear‐thinning fluids used: this elasticity is not taken into account in the Carreau‐A model.
On some optimization procedures for shock localization
Authors: Vorozhtsov E. V. , Yanenko N. N. 
Published: August 2005

AbstractWe consider a problem on shock wave localization in the numerical solution of one‐dimensional unsteady problems of gas dynamics in Eulerian variables obtained on the basis of finite difference shock‐capturing schemes. An optimization method for strong discontinuity localization proposed previously by Miranker and Pironneau is investigated by means of methods of classical variational calculus. This method may be difficult to implement when the entropy condition is included in the formulation of Miranker and Pironneau's optimization problem as an active constraint. In this connection we suggest an alternative optimization problem using artificial viscosity in the variational principle. It is shown theoretically that the application of such a variational principle yields a trajectory which coincides with the true discontinuity trajectory in the case of a shock wave moving at a constant speed. On the basis of this modification one more algorithm is proposed which reduces the shock localization problem to a problem of minimization of a univariate function. Numerical tests corroborate completely the theoretical conclusions. In particular, a higher shock localization accuracy is obtained on the basis of the proposed algorithms as compared to the original Miranker‐Pironneau method.
The effectiveness of dampers for the analysis of exterior scalar wave diffraction by cylinders and ellipsoids
Authors: Bando K. , Bettess P. , Emson C. 
Published: August 2005

AbstractThe technique of dampers is now widely used in the numerical analysis of unbounded problems. The dampers are used to absorb the outgoing waves. This paper will consider in detail the best formulations of damper methods. Examples will be given showing the effectiveness of three different dampers, in two dimensional and three dimensional models. The geometries considered are circular and elliptical cylinders, spheres and ellipsoids. The results indicate that dampers are indeed very effective, particularly those of higher order, which have recently been developed by Bayliss et al.1,2 and others.
Development of a computer program for the prediction of flow in a rotating cavity
Authors: Chew J. W. 
Published: August 2005

AbstractA computer program has been developed to predict laminar source‐sink flow in a rotating cylindrical cavity. Although the program is based on a standard finite difference technique for recirculating flow, it incorporates two novel features. Step changes in grid size are employed to obtain sufficient resolution in the boundary layers and special treatment is given to the solution of the pressure correction equations, in the ‘SIMPLE’ algorithm, in order to improve the convergence properties of the method. Results are presented both for the flow in an infinite rotating cylindrical annulus and a finite rotating cylindrical cavity, with the inner cylindrical surface acting as a uniform source and the outer cylinder as a sink. These show good agreement with existing analytical solutions and illustrate some of the problems associated with the computation of rapidly rotating flows.
The solution of non‐linear hyperbolic equation systems by the finite element method
Authors: Löhner R. , Morgan K. , Zienkiewicz O. C. 
Published: August 2005

AbstractThe difficulties experienced in the treatment of hyperbolic systems of equations by the finite element method (or other) spatial discretization procedures are well known. In this paper a temporal discretization precedes the spatial one which in principle is considered along the characteristics to achieve a self adjoint form. By a suitable expansion, the original co‐ordinates are preserved and combined with the use of a standard Galerkin process to achieve an accurate discretization. It is shown that the process is equivalent to the Taylor‐Galerkin methods of Donea.17Several examples illustrate the accuracy and efficiency attainable in such problems as transport, shallow water equations, transonic flow etc.