bluuebunny/crossref_metadata_2025_split huggingface dataset:
ODE solvers and the method of lines
Authors: Shampine L. F. 
Published: August 2005

AbstractFactors influencing the choice of ODE solver for the numerical solution of PDEs by the method of lines are investigated. The advection—diffusion equation is used to gain insight that is generalized to some classes of nonlinear PDEs. Numerical results for several nonlinear PDEs illustrate the theoretical developments. © 1994 John Wiley & Sons, Inc.
Some pointwise estimates for the finite element solution of a radial nonlinear Schrödinger equation on a class of nonuniform grids
Authors: Tourigny Yves 
Published: August 2005

AbstractWe prove new pointwise estimates for the time‐continuous finite element discretization of a nonlinear Schrödinger equation. The analysis relies on the energy method. A superconvergent estimate of the error gradient is derived and we obtain L∞ estimates via inverse inequalities. We emphasize the case of radial symmetry where the results improve on previously published L2 estimates by allowing greater flexibility in the choice of spatial grid. Some numerical results are presented, which confirm our theoretical findings. © 1994 John Wiley & Sons, Inc.
Superconvergence of finite element approximations to Maxwell's equations
Authors: Monk Peter 
Published: August 2005

AbstractWe study superconvergence of edge finite element approximations to the magnetostatic problem and to the time‐dependent Maxwell system. We show that in special discrete norms there is an increase of one power in the order of convergence of the finite element method compared to error estimates in standard Sobolev norms. Our results are restricted to an orthogonal grid inR3, but the grid may be nonuniform. © 1994 John Wiley & Sons, Inc.
Difference approximations for wave equations via finite elements II. Error analysis
Authors: Card Curtis L. , Allen Myron B. 
Published: August 2005

AbstractDifference‐like schemes for the wave equation arise naturally from a Galerkin finite‐element formulation, if we adopt certain quadrature rules in evaluating the mass and stiffness matrices. One can extend these schemes to problems involving sharp interfaces by applying the quadrature on a refinement of the finite‐element grid that includes the interfaces. We develop error estimates for this modified scheme that corroborate numerical results for acoustic and elastic wave equations, presented in a companion article. © 1995 John Wiley & Sons, Inc.
Incremental unknowns for solving nonlinear eigenvalue problems: New multiresolution methods
Authors: Chehab Jean–Paul , Temam Roger 
Published: August 2005

AbstractIn this article, we present several numerical multilevel schemes for the solution of nonlinear eigenvalue problems. Using the Incremental Unknowns, we construct some generalization of the Marder and Weitzner method, which is well suited for the calculation of unstable solutions. The new methods that we present are based on a different treatment of the several structures appearing with the utilization of the hierarchical preconditioner. We illustrate the efficiency of the new methods with the calculation of unstable solutions of a reaction diffusion problem. © 1995 John Wiley & Sons, Inc.
Eulerian–Lagrangian localized adjoint methods for reactive transport with biodegradation
Authors: Wang Hong , Ewing Richard E. , Celia Michael A. 
Published: August 2005

AbstractThe microbial degradation of organic contaminants in the subsurface holds significant potential as a mechanism for in‐situ remediation strategies. The mathematical models that describe contaminant transport with biodegradation involve a set of advective–diffusive–reactive transport equations. These equations are coupled through the nonlinear reaction terms, which may involve reactions with all of the species and are themselves coupled to growth equations for the subsurface bacterial populations. In this article, we develop Eulerian–Lagrangian localized adjoint methods (ELLAM) to solve these transport equations. ELLAM are formulated to systematically adapt to the changing features of governing partial differential equations. The relative importance of retardation, advection, diffusion, and reaction is directly incorporated into the numerical method by judicious choice of the test functions that appear in the weak form of the governing equation. Different ELLAM schemes for linear variable–coefficient advective–diffusive–reactive transport equations are developed based on different operator splittings. Specific linearization techniques are discussed and are combined with the ELLAM schemes to solve the nonlinear, multispecies transport equations. © 1995 John Wiley & Sons, Inc.
On the solution of a 2‐D, parabolic, partial differential energy equation subjected to a nonlinear convective boundary condition via a simple solution for a uniform, Dirichlet boundary condition
Authors: Campo Antonio , Lacoa Ulises 
Published: August 2005

AbstractSeparate theoretical and numerical analyses have been conducted for the prediction of the mean bulk‐and wall‐temperatures of hot fluids flowing inside horizontal tubes. Heat transmission between the internal forced flow and the external free flow of the surrounding fluid occurs through the solid wall of the tube. The mathematical formulation of this problem is expressed in terms of a parabolic, partial differential equation with a temperature‐dependent, nonlinear boundary condition of third kind. The aim of the article is to critically examine the thermal response of this kind of in‐tube flows utilizing two different mathematical models: (a) a complete 2‐D differential model and (b) a largely simplified 1‐D lumped model. For the 1‐D lumped model, streamwise‐mean values for the internal Nusselt numbers and the circumferential‐mean values for the external Nusselt numbers have been taken from standard correlations that appear in basic textbooks. The combination of both mean Nusselt numbers leads to the calculation of a mean, equivalent Nusselt number, which serves to regulate the thermal interaction between the perpendicular fluid streams. For the two models tested, the computed results consistently demonstrate that the simplistic 1‐D lumped model provides accurate estimates of the mean bulk‐ and wall‐temperatures, when compared with those computed with the rigorous 2‐D differential model. The former is associated with hand calculations, whereas the latter inevitably necessitated a finite‐difference methodology and a personal computer. © 1995 John Wiley & Sons, Inc.
A moving grid finite‐element method using grid deformation
Authors: Semper Bill , Liao Guojun 
Published: August 2005

AbstractA new front tracking method based on grid deformation is combined with a streamline upwind Petrov–Galerkin finite element method to produce an adaptive method for application to convection‐dominated transport equations. In this work, we examine the practicality of this approach and demonstrate the method on one‐dimensional examples. © 1995 John Wiley & Sons, Inc.
A biplicit spectral‐collocation‐type ansatz for the numerical integration of partial differential equations with the transversal method of lines
Authors: Reiter Johann 
Published: August 2005

AbstractIn the implicit formulation of the transversal method of lines, numerical instabilities (singular perturbation) do occur whenever “small” step sizes of the discretized variable have to be used for some reason. This problem can effectively be avoided if the derivatives with respect to the discretized variable are chosen using a combination of implicit and explicit methods (the biplicit method). This combination method uses piecewise defined trial functions involving a certain number of free parameters. The values of these parameters are found by the requirement that the trial functions approximate the solution of the implicit formulation of the method of lines. From a mathematical point of view, this spectral‐collocation‐type ansatz results in a multipoint boundary‐value problem with added parameters to be determined. Two numerical examples are presented in order to illustrate the performance of the method. © 1995 John Wiley & Sons, Inc.
Structures of three crystal modifications of poly(3,3‐dimethyloxacyclobutane)
Authors: Takahashi Yasuhiro , Osaki Yasunari , Tadokoro Hiroyuki 
Published: August 2005

AbstractThree crystal modifications of poly(3,3‐dimethyloxacyclobutane) [CH2C(CH3)2CH2O]n were found and their structures were analyzed by x‐ray diffraction. Modification I is obtained only under tension and disappears on relaxing the tension. From the fiber period of 4.83 Å, the molecular structure seems to be planar zigzag. In modification II, two chains in T3GT3Ḡ conformation pass through a monoclinic cell with parameters a = 8.93 Å, b = 7.48 Å, c (fiber axis) = 8.35 Å, β = 97.9°, and the space group P21/c‐C. In modification III, two (T2G2)2 chains pass through an orthorhombic cell with parameters a = 15.60 Å, b = 5.74 Å, c (fiber axis) = 6.51 Å, and the space group, C2221–D. Molecular conformations of the three crystal modifications correspond to those of polyoxacyclobutane.
Stress relaxation of polymeric liquids after double‐step strain
Authors: Doi Masao 
Published: August 2005

AbstractThe stress relaxation of concentrated polymer solutions after double‐step strain is analyzed by the model of Doi and Edwards (DE model). The theory explains the experiments of Osaki et al., who showed that the Bernstein–Kearsley–Zapas (BKZ) constitutive equation works reasonably well when the successive deformations are applied in the same direction, but that it fails when the direction of the second deformation is reversed. This experimental result has been considered contrary to the DE model, since the previous theory of Doi and Edwards provides a BKZ‐type constitutive equation. In the present paper the discrepancy is reconciled by showing that (i) the source of the discrepancy is a mathematical approximation used in the previous DE theory, and that (ii) if this approximation is removed, the agreement between the theory and experiment becomes fairly good.
Piezoelectricity and pyroelectricity of polyvinylidene fluoride corona‐poled at elevated temperature
Authors: Bamji S. S. , Kao K. J. , Perlman M. M. 
Published: August 2005

AbstractX‐ray diffraction, thermally stimulated depolarization, and piezoelectric and pyroelectric current measurements have been carried out on biaxially oriented polyvinylidene fluoride film, corona‐poled both negatively and positively, at elevated temperature. Larger piezoelectric and pyroelectric coefficients are obtained at lower values of the poling field, when corona charging takes place at elevated temperature rather than room temperature. Negative charging is more effective than positive. The polarization mechanism is dipole alignment, and a conversion of Form‐II crystallites to Form I. The large space‐charge injected by the corona, and trapped in the material, acts through creation of high internal fields, and shows little, if any, piezoelectric and pyroelectric effects of its own.
“Super microcapsules” (SMC). I. Preparation and characterization of star polymethylene oxide (PEO)polylactide (PLA) copolymers
Authors: Zhu K. J. , Bihai Song , Shilin Yang 
Published: August 2005

AbstractA new model of molecular scale microcapsule named “super microcapsule” (SMC) obtained from a star copolymer consisting of hydrophilic and hydrophobic blocks was presented. As a first stage, 3 and 4‐arm star polyethylene oxide‐polylactide copolymers (s‐PEO‐PLA) were synthesized by the use of triethanolamine and pentaerythritol and initiating agent, respectively. The block length of PLA and PEO for the copolymers can be controlled by feed and reaction conditions. The molecular weight distributions found to be in the range of 1.3–1.7. The DTA data indicated that the phase separation behavior of s‐PEOPLA copolymers is different from that of linear PEOPLA copolymers with comparable block length. As a evidence of SMC, the shell‐core structure of s‐PEOPLA copolymers in solid state was observed by TEM. The SMC dimensions were estimated to be about 400–1000 Å
Cationic polymerization of α‐methylstyrene in dichloromethane initiated with system 2,5‐dichloro‐2,5‐dimethylhexene‐BCl3. II. Continuous addition of monomer into initiator, quasiliving polymerization
Authors: Toman Luděk , Pokorný Svatopluk , Spěváček Jiří 
Published: August 2005

AbstractA slow continuous addition of dichloromethana solutions of α‐methylstyrene (α‐MeSt) into a dichloromethane solution of 2,5‐dichloro‐2,5‐dimethylhexane (DDH) with BCI3 (initiating system II) prepared in advance resulted, in the temperature range between −20 and −40°, in a quasilving polymerization of α‐MeSt. At −20°C and a 100% conversion a polymer with a very narrow molecular weight distribution is formed, M̄w/M̄n ‐ 1.1. Quasiliving polymerization of α‐MeSt has not been achieved with freshly prepared dischloromethane solutions of DDH with BC3 (initiating sytem I), or with solutions of BCI3 alone (initiating system III). Polarity of the polymerization medium affected molecular weight distribution (MWD) of the polymer, and the polydispersity index decreased with decreasing polarity. MWD of the polymer samples were studied by the GPC method, the structure of poly (α‐methylstyrene) (Pα‐MeSt) was investigated by the 1H‐NMR analysis
Syntheses and properties of 4‐hydroxy‐3,5‐dibromobenzyl phosphonates and their flame‐retarding effects on ABS copolymer
Authors: Yang Chin‐Ping , Lee Tzong‐Ming 
Published: August 2005

Abstract4‐Hydroxy‐3,5‐dibromobenzyl phosphonates (HDBBP) were synthesized by reacting phosphites with 4‐hydroxy‐3,5‐dibromobenzyl bromide (HDBBB) which was prepared in advance by photobromination of 2,6‐dibromo‐p‐cresol (DBPC) produced by bromination of p‐cresol. In the reactions between HDBBB and phosphites, the rate of formation of dimethyl 4‐hydroxy‐3,5‐dibromobenzyl phosphonate (HDBBPm) was greater than that of diphenyl 4‐hydroxy‐3,5‐dibromobenzyl phosphonate (HDBBPP); however, quantitative yields for both products were obtainable. The addition of HDBBP as bromine and phosphorus containing flame‐retardants to ABS copolymer showed better results than the addition of the same amount of brominated compound, or mixtures of both two compounds. It was also proved that compound containing both bromine and phosphorus exhibited more apparent synergistic effects on flame retardancy than the mixtures of brominated compound and phosphorous containing compound
Free radical copolymerization of sulfur dioxide with 1‐alkynes
Authors: Kim Seong‐Ju , Matsuda Minoru 
Published: August 2005

AbstractFree radical copolymerization of SO2 with 1‐alkynes (AY) was studied by evaluation of the copolymerization rate under controlled conditions of copolymerization temperature and monomer concentration product ([AY][SO2]). The poly(alkyne sulfone)s always contained equimolar units of SO2 and alkyne, regardless of the copolymerization conditions. Using 1‐hexyne (HY) and 1‐octyne (OY) as comonomers of SO2, the values of ceiling temperature (Tc) were determined: when [HY][SO2] = [OY][SO2] = 0.25 mol2/L2, the values of Tc were 90.5 and 84.5°C, respectively. Tc increases with increasing monomer concentration product. The activation energies for propagation (Ep) and depropagation (Ed) of the SO2‐alkynes copolymerization system were investigated, using the SO2OY copolymerization system, and estimated to be 12.2 and 26.7 kcal/mol, respectively. The value of Ed is high compared with that of the copolymerization of SO2 and 1‐butene (20.3 kcal/mol), demonstrating that the free radical endings (∼ OYSO2 and ∼ SO2OY) are difficult to depropagate, compared with those formed from the copolymerizaton of SO2 and 1‐butene. ΔS and ΔHp, calculated from experiments, were found to be −37.7 cal/mol K and −14.3 kcal/mol, respectively
Polymer degradation under ionizing radiation: The role of ozone
Authors: Clough R. L. , Gillen K. T. 
Published: August 2005

AbstractGamma‐radiation degradation of poly(butadiene‐co‐styene) [SBR rubber] and poly(butadiene‐co‐acrylonitrile) [Buna‐n rubber] in the presence of air has been investigated. Using a recently‐developed modulus profiling techniques, it is shown that the degradation of these materials is very heterogenous through the sample thickness. There is a broad, paraboloidally‐shaped modulus profile through the sample interior, together with a dramatic change in modulus in the surface regions. Mechanistic investigations lead to the conclusion that the radiation‐inducted degradatoin of these materials results from two different process: (1) the standard free radical‐mediated radiation chemistry, which gives rise to oxidation involving O2 dissolved in the polymer and which leads to heterogenous oxidation due to oxygen diffusion effects; and (2) ozone chemistry in the surface regions of the samples, which results from attack by O3 generated by the action of the ionizing radiation on the air atmosphere surrounding the samples. It appears that the intense role which this ozone mechanism can play in radiation‐induced oxidative degradation of polymers has not been widely appreciated. This study provides evidence that the simultaneous action of ozone and ionizing radiation can in fact be strongly synergistic in their effect on organic materials
A study of the mechanism of aniline polymerization
Authors: Wei Yen , Tang Xun , Sun Yan , Focke Walter W. 
Published: August 2005

AbstractA chemical polymerization of aniline is quenched at specific reaction time intervals and the amounts of unreacted aniline and formed p‐aminodiphenylamine is observed. Oxidation of aniline to generate p‐aminodiphenylamine is observed. Oxidation of aniline to generate p‐aminodiphenylamine is the slow step in the plymerization. Furthermore, the tetramer of aniline is used as starting material for polymerization under the same conditions as polymerization of aniline. Direct coupling of two tetramers leading to polymer is not observed. A mechanism of polymerization of aniline is proposed
Thioether glycidyl resins. VI. Reaction products of opening of oxirane ring of phenylthioetherglycidyl resin and of some derivatives under the influence of temperature
Authors: Charmas Władysław , Podkościelny Wawrzyniec , Brunn Joachim 
Published: August 2005

AbstractThe process of oxirane ring opening of thioether glycidyl resins under various temperatures has been described. Reaction rate constants (k) and the activaton parameters (Eα, ΔH*, ΔS*) for epoxy group loss of 1,2‐epoxy‐3‐(phenylthio)propane, 1,2‐epoxy‐3‐(p‐tolythio)propane, and 1,2‐epoxy‐3‐(p‐chloro‐phenylthio)propane using classical kinetic methods were determined. The reaction products were separated and analyzed by means of chromatography and the structure of the compounds was determined by means of the spectral analyses: IR, 1H‐NMR, and 13C‐NMR
Thermoplasticization of wood. I. Benzylation of wood
Authors: Hon David N.‐S. , Ou Nian‐Hua 
Published: August 2005

AbstractA study of converting wood into thermoplastic materials was undertaken to develop a new technique in effective utilization of wood wastes. Thermoplasticizatoin of wood carried out by means benzylation. Various reaction parameters, such as alkalinity of reaction media, reaction temperature, and time were taken into account to produce benzylated wood with different degrees of substitution (based on weight gain) FTIR, DSC, DMTA, SEM and x‐ray crystallography were used to characterize the chemical and mechanical properties of benzylated wood. Experimental data showed that preswelling and reaction temperature had critical effects on benzylation reaction. Lignin in wood appeared to inhibit benzylation but extractives had little effect. Different species showed some variation in reaction rates. The thermoplasticized wood exhibited good melting properties and were readily molded into bulk materials or extruded into films and sheets. A wide range of glass transition temperatures from 66 to 280°C for the benezylatedwoods was achieved, and they were larely dependent on the weight gain. The molded and extruded products exhibited acceptable mechanical strength for structural engineering applications. The property and structure relationship for the thermoplasticized wood were discussed
Effect of aging on fractional crystallization of poly(ethylene oxide) component in poly(ethylene oxide)/poly(3‐hydroxybutyrate) blends
Authors: Zhao Li , Kai Weihua , He Yong , Zhu Bo , Inoue Yoshio 
Published: August 2005

AbstractThe effect of aging on the fractional crystallization of the poly(ethylene oxide) (PEO) component in the PEO/poly(3‐hydroxybutyrate) (PHB) blend has been investigated. The partial miscibility of the PEO/PHB blends with high PEO molecular weight (Mv = 2.0 × 105 g/mol) was confirmed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis. The fractional crystallization behavior of the PEO component in the PEO/PHB blends with low PEO content (not more than 30 wt% of PEO), before and after aging under vacuum at 25 °C for 6 months, were compared by DSC, fourier transform infrared microscopic spectroscopy, small angle X‐ray diffraction, and scanning electron microscopy. It was confirmed that nearly all the PEO components remain trapped within interlamellar regions of PHB for the PEO/PHB blends before aging. Under this condition, the crystallization of PEO is basically induced by much less active heterogeneities or homogeneous nucleation at high supercoolings. While, after the same PEO/PHB samples were stored at 25 °C in vacuum for 6 months, a part of the PEO component was expelled from the interlamellar region of PHB. Under this condition, the expelled PEO forms many separate domains with bigger size and crystallizes at low supercoolings by active heterogeneous nucleation, whereas the crystallization of PEO in the interlamellar region is still mainly induced by less active heterogeneities or homogeneous nucleation at extreme supercoolings. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2665–2676, 2005
Rheological properties and interfacial slip of a multilayer structure under dynamic shear
Authors: Jiang L. , Lam Y. C. , Zhang J. 
Published: August 2005

AbstractInterfacial slip between polymer melt under steady shear has been studied using a simplified multilayer structure. In this investigation, interfacial slip under dynamic shear was studied by calculating the angular displacements of the multilayer structure and its component layers. On the basis of the angular displacements, a slip index was defined to quantify the degree of interfacial slip. A relationship governing the rheological behavior of the multilayer structure under slip and nonslip condition was established. These results were correlated with equations derived from consideration of energy equilibrium in the multilayer structure. Polymer multilayer structures of high‐density polyethylene/polystyrene and liquid crystal polymer(LCP)/poly ethylene naphthalate(PEN) were investigated. Of all the polymers investigated, large interfacial slip was found at LCP/PEN interface under dynamic shear. The high rigidity and alignment along the interface of LCP molecules was believed to prevent chain entanglement in the interfacial layer and therefore promote interfacial slip at the interface. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2683–2693, 2005
Crystal structure of poly(dithiotriethylene adipate)
Authors: Finelli Lara , Gazzano Massimo , Lotti Nadia , Malta Viscardo , Munari Andrea 
Published: August 2005

AbstractThe crystal structure of poly(dithiotriethylene adipate) has been determined through the best fitting of calculated and experimental X‐ray diffraction powder profiles. A triclinic cell was found with dimensionsa= 4.942 (7) Å,b= 4.702 (2) Å,c= 20.56 (2) Å, α = 88.9 (2)°, β = 61.0 (1)°, γ = 67.8 (1)°, P‐1 space group, and one chain in the unit cell. A full extended trans conformation of the chain fitted satisfactory the experimental data, yielding to a discrepancy factorRp= 0.073. A comparison between the crystal structures of poly(dithiotriethylene adipate) and poly (thiodiethylene adipate) is proposed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2677–2682, 2005