bluuebunny/crossref_metadata_2025_split huggingface dataset:
An approach to verifying and debugging simulation models governed by ordinary differential equations: Part 1. Methodology for residual generation
Authors: Yuan Zhiguo , Graham Malcolm L. , Lennox James A. 
Published: April 2003

AbstractFor dynamic simulations to be credible, verification of the computer code must be an integral part of the modelling process. This two‐part paper describes a novel approach to verification through program testing and debugging. In Part 1, a methodology is presented for detecting and isolating coding errors using back‐to‐back testing. Residuals are generated by comparing the output of two independent implementations, in response to identical inputs. The key feature of the methodology is that a specially modified observer is created using one of the implementations, so as to impose an error‐dependent structure on these residuals. Each error can be associated with a fixed and known subspace, permitting errors to be isolated to specific equations in the code. It is shown that the geometric properties extend to multiple errors in either one of the two implementations. Copyright © 2003 John Wiley & Sons, Ltd.
An approach to verifying and debugging simulation models governed by ordinary differential equations: Part 2. Residuals analysis and a case study
Authors: Lennox James A. , Yuan Zhiguo 
Published: April 2003

AbstractIn Part 1 of this paper a methodology for back‐to‐back testing of simulation software was described. Residuals with error‐dependent geometric properties were generated. A set of potential coding errors was enumerated, along with a corresponding set of feature matrices, which describe the geometric properties imposed on the residuals by each of the errors. In this part of the paper, an algorithm is developed to isolate the coding errors present by analysing the residuals. A set of errors is isolated when the subspace spanned by their combined feature matrices corresponds to that of the residuals. Individual feature matrices are compared to the residuals and classified as ‘definite’, ‘possible’ or ‘impossible’. The status of ‘possible’ errors is resolved using a dynamic subset testing algorithm. To demonstrate and validate the testing methodology presented in Part 1 and the isolation algorithm presented in Part 2, a case study is presented using a model for biological wastewater treatment. Both single and simultaneous errors that are deliberately introduced into the simulation code are correctly detected and isolated. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling topology optimization problems as linear mixed 0–1 programs
Authors: Stolpe M. , Svanberg K. 
Published: April 2003

AbstractThis paper deals with topology optimization of discretized continuum structures. It is shown that a large class of non‐linear 0–1 topology optimization problems, including stress‐ and displacement‐constrained minimum weight problems, can equivalently be modelled as linear mixed 0–1 programs. The modelling approach is applied to some test problems which are solved to global optimality. Copyright © 2003 John Wiley & Sons, Ltd.
A developmental study of the Bonner Foundation's scholarship recipients: Impact of a four‐year, cocurricular service‐learning model
Authors: Keen Cheryl , Keen James P. 
Published: April 2003

AbstractPreliminary research findings indicate that a four‐year, cocurricular service‐learning model supports an exemplary group of low‐income students in sustaining and deepening their commitments to service. It also provides skills germane to life success as well as unique opportunities for experience and reflection.
An analysis of the swelling equilibrium of an ionic polymer network in a binary liquid mixture
Authors: Iwatsubo Takashi , Masuoka Toshio , Mizoguchi Kensaku 
Published: April 2003

AbstractAn equation which represents the swelling equilibrium of an ionic polymer network in a binary liquid mixture is introduced and evaluated numerically. Discontinuous volume changes are obtained with pertinent values of the parameters. From two types of dependence of the degree of ionic dissociation on the composition of a liquid mixture, two types of volume transitions of an ionic gel are illustrated. One is the transition typically seen in acrylamide gels, and the other is a re‐entrant transition typical of isopropylacrylamide gels. The selective dissolution factor of two liquids into a swollen polymer network also becomes discontinuous in accordance with the discontinuous volume change. Transition points and the spinodal line are calculated from a generalized form of the free energy change of the swollen gel system. © 1994 John Wiley & Sons, Inc.
Compatibilizing effect of polyarylate‐polystyrene block copolymer in polyarylate/polystyrene blends
Authors: Ahn Tae Oan , Kim Jung Ho , Jeong Han Mo , Lee Sang Won , Park Lee Soon 
Published: April 2003

AbstractThe compatibilizing effect of polyarylate‐polystyrene (PAR‐PS) block copolymer prepared from macroazo initiator was examined in polyarylate/polystyrene blends from the view‐points of morphology, density, and thermal, mechanical, and rheological properties. PARPS block copolymer enhanced the mutual dissolution of the homopolymers. Reduced dispersed‐domain size and increased density showed the efficiency of the block copolymer as a compatibilizing agent. Results from mechanical and rheological properties could also be explained by the compatibilizing effect of PAR‐PS block copolymer in the blends. © 1994 John Wiley & Sons, Inc.
FTIR Investigation of ion‐dipole interaction in styrene ionomer/poly(ethylene oxide) blends
Authors: Lim Jong‐Chul , Park Jung‐Ki , Song Hae‐Young 
Published: April 2003

AbstractFourier‐transform infrared (FTIR) spectroscopy was used to examine specific interactions contributing to the partial miscibility in blends of styrene‐sodium methacrylate copolymer (S‐NaMA) and poly(ethylene oxide) (PEO). From the shifts of carboxylatelon and ether group stretching bands, an important specific interaction was found involving ion‐dipole bonding between the ionic group in styrene ionomer and the ether group in PEO. The asymmetric stretching vibration frequency of the carboxylate ion group increases as the fractional amount of PEO in the blend is increased, while the symmetric stretching frequency is decreased. The transition value of the fraction of PEO, above which both vibration frequencies of the carboxylate ion mentioned above remained almost unchanged, increases as the concentration of ionic groups in ionomer is increased. The ether group stretching band shifts to higher frequencies as the PEO content in the ionomer/PEO blend is increased. From the differential scanning calorimetry (DSC) and FTIR studies, we find that the iondipole interaction is the important mechanism that determines the miscibility of S‐NaMA/PEO blends. © 1994 John Wiley & Sons, Inc.
ESR and magnetic properties of electrically conducting metallophthalocyanine polymers
Authors: Venkatachalam S. , Rao K. V. C. , Manoharan P. T. 
Published: April 2003

AbstractPolymeric metallophthalocyanines of Cu, Ni, Co in which benzene rings are shared in common with the macrocyclic phthalocyanine rings containing peripheral carboxylic groups have been synthesized and their electrical conductivities are shown to increase from 5 to 8 orders of magnitude by thermal treatment. The cobalt polymer exhibits greater conductivity than its nickel or copper analogs. The heated polymers show very broad electron spin resonance (ESR) signals and large paramagnetic susceptibilities. The bulk magnetic susceptibility of these polymers shows Curie‐like behavior when the samples are heated from room temperature to 473 K. This is explained on the basis of coexistence of fixed mobile and conduction electron spins in the system and the interaction of the soliton type defects present in these polymers with the polymeric network to give dipolar charge carriers. This is also supported by the decrease in ESR intensity with increasing temperature when the samples are heated in the ESR cavity. The effect of the presence of unpaired electrons on the d shell of the central metal atoms on the line width and the line shape of the ESR spectra is also explained. © 1994 John Wiley & Sons, Inc.
Permeability relationships of polyimide copolymers
Authors: Zoia G. , Stern S. A. , St. Clair A. K. , Pratt J. R. 
Published: April 2003

AbstractThe permeability of the homopolymers 6FDA‐3BDAF and 6FDA‐4BDAF and of the copolymers 6FDA‐4/2BDAF, 6FDA‐4/3BDAF, and 6FDA‐4/3/2BDAF to He, CO2, and CH4 was measured at 35.0°C and at pressures up to 10 atm. The experimental values of the permeability coefficients for the copolymers are in satisfactory agreement with the values estimated from the permeability coefficients for the constituent homopolymers and their weight fractions. The synthesis of the fluorine‐containing diamine 2BDAF is reported for the first time. © 1994 John Wiley & Sons, Inc.
Thermal conductivity of poly(vinyl chloride)/polycaprolactone blends
Authors: Agari Y. , Ueda A. 
Published: April 2003

AbstractThermal diffusivity, heat capacity, and density of polyvinyl chloride/polycaprolactone (PVC/PCL) blends were measured by the laser flash method, DSC, and pycnometry, respectively. The thermal conductivity of the PVC/PCL blends was determined from the results. The miscibility of the blend and crystallinity of PCL were determined by DSC. The effect of blend structure on thermal conductivity is discussed. The phase compositions of the PVC/PCL blends are of three types depending on PCL content: i.e., up to 33%, from 33 to 70%, and above 70% PCL by weight. Thermal conductivity, thermal diffusivity, and heat capacity of the PVC/PCL blends are strongly affected by the phase composition of the blend, which changes in a complicated way with PCL content. © 1994 John Wiley & Sons, Inc.
Light scattering studies of copolymers. 1. Soluble hemoglobin‐‐dextran complexes
Authors: Nordmeier Eckhard , Rad Darush 
Published: April 2003

AbstractComplexes between dextrans of different molar mass and bovine hemoglobin were synthesized by two different methods. In the alkylation method three and in the dialdehyde method, two hemoglobins are coupled on average to one dextran molecule. In both cases, the soluble hemoglobin‐dextran complexes reversibly bind and release oxygen; the oxygen affinity is greater than that of free hemoglobin. Static and dynamic light scattering was used to determine the average molar mass Mu, the radius of gyration 〈S〉, and the hydrodynamic radius Rh of both the complexes and the single dextrans. Interpretation of these data is complicated due to the fact that the complexes are copolymers. When appropriate approximations are made, the results indicate that the complexes have a spherical shape and an internal structure of a multiple‐chain network, where several dextrans are linked together by the hemoglobins. The number of single dextrans per complex increases as the molar mass of the single dextrans is decreased. The increment is greater in the dialdehyde than in the alkylation method. The probable reason is that in the dialdehyde method one hemoglobin can connect many dextrans simultaneously while in the alkylation method a hemoglobin is able to link maximally two dextrans. The ratio of the radius of gyration to the hydrodynamic radius decreases as the temperature is increased. This suggests a decrease of the solvent penetration length for the complexes and can be interpreted on the basis of the Deutsch‐Felderhof theory for porous spheres. © 1994 John Wiley & Sons, Inc.
Pulsed NMR study of the structure of poly(vinyl alcohol)‐poly(sodium acrylate) composite hydrogel
Authors: Shiga T. , Fukumori K. , Hirose Y. , Okada A. , Kurauchi T. 
Published: April 2003

AbstractThe heterogeneous structure of poly(vinyl alcohol)‐poly(sodium acrylate) composite hydrogels (PVA‐PAA gels), prepared by repeatedly freezing and thawing mixed aqueous solutions of PVA and PAA, has been studied using pulsed NMR. The free induction decay (FID) signals of the transverse magnetization for the PVA‐PAA gels were measured by both Carr‐Purcell‐Meiboom‐Gill and solid‐echo pulse sequences. The FID signal was decomposed into two or three decaying signals with various spin‐spin relaxation times, based upon differences in the molecular mobility that reflected structural heterogeneity. The structural heterogeneity of the PVA‐PAA gel is quite different from that of PVA gel free of PAA. We have made observations on “crosslinked” domains in the PVA‐PAA gels. They are formed by PVA solid chains, probably phase‐separated in the freezing‐thawing process. The formation of crosslinked domains is influenced by the number of freezing‐thawing cycles. © 1994 John Wiley & Sons, Inc.
Interaction of water with poly(vinyl methyl ether) in aqueous solution
Authors: Maeda Hideatsu 
Published: April 2003

AbstractNear‐infrared, viscometric, and calorimetric measurements were made on aqueous poly(vinyl methyl ether) (PVME) solutions at temperatures between 15 and 43°C. We found a hydrogen‐bonded structure of water around the polymer chain (a polymer‐water complex), which is characterized by two distinct hydration numbers (i.e., 2.7 and 5.0 water molecules on each monomer unit of the chain) by analyzing the concentration dependence of endothermic enthalpies at a cloud point temperature, ca. 35°C. In particular, the 2.7 water‐polymer complex has been suggested to be cooperatively formed by using data of the near‐infrared (nir) absorption spectrum around 1930 nm. Furthermore, the peak‐wavelength of the nir spectrum has been observed to change drastically at the cloud point when the temperature is raised. This can be interpreted as a cooperative collapse of the hydrogen‐bonded water structure to free water, resulting in the aggregation of the polymer chains due to the exposure of their hydrophobic groups at the cloud point. © 1994 John Wiley & Sons, Inc.
Structural aspects of suspension poly(vinyl chloride): Influence of temperature on the macro‐ and microstructure
Authors: Scherrenberg R. L. , Reynaers H. , Gondard C. , Booij M. 
Published: April 2003

AbstractThe structural aspects of rigid suspension poly(vinyl chloride), PVC, have been investigated on the basis of two independent series of suspension PVC samples, polymerized at temperatures between 26 and 84°C. The reproducibility of the suspension polymerization process and the importance of the polymerization temperature with respect to the macro‐ and microstructure is demonstrated. Quantitative examination of the grain structure by small angle neutron scattering, Brunauer‐Emmett‐Teller absorption technique, and mercury porosimetry clarifies the gradual increase of the specific surface on lowering the polymerization temperature. A detailed WAXS study shows an increasing degree of crystallinity on lowering the polymerization temperature, which can be associated with the corresponding increase of the syndiotacticity. Furthermore, the presence of a polymerization history in the PVC powders with respect to the crystallinity is evidenced. This effect seems to be related to chain mobility restrictions during the polymerization process and is determined by the difference between the polymerization temperature and the glass‐transition temperature (Tg) of rigid PVC. This so‐called Tg effect is indicative of the fact that no appreciable swelling of PVC by its monomer occurs. © 1994 John Wiley & Sons, Inc.
Structural aspects of suspension poly(vinyl chloride): The thermal aspects of rigid suspension PVC
Authors: Scherrenberg R. L. , Reynaers H. , Gondard C. , Steeman P. A. M. 
Published: April 2003

AbstractThe thermal aspects of a series of suspension PVC samples, polymerized at different temperatures, have been investigated using DSC, WAXS, and dielectric measurements. The observed thermal behavior, extending over a wide temperature range, is in line with the presence of ordered entities, having a wide distribution of size and perfection. The importance of small variations of the syndiotacticity on the crystallizability is demonstrated by cooling experiments. © 1994 John Wiley & Sons, Inc.
Phase morphology of blends of polycarbonate with poly(methyl methacrylate‐co‐cyclohexyl methacrylate), and of polycarbonate with poly(methyl methacrylate) by solid state nuclear magnetic resonance, differential scanning calorimetry, and transmission electron microscopy
Authors: Hung C.‐C. , Carson W. G. , Bohan S. P. 
Published: April 2003

AbstractThe miscibility of polycarbonate (PC) with poly(methyl methacrylate‐co‐cyclohexyl methacrylate) (PMCHM) and with poly(methyl methacrylate) (PMMA) was studied by nuclear magnetic resonance (NMR) 1H spin‐lattice relaxation time in the rotating frame (1H T1p), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). A blend of PC/PMCHM (50/50 wt/wt) with the acrylic component PMCHM, a copolymer of PMMA and poly(cyclohexyl methacrylate) (80/20 wt/wt), shows only one T1p value, which indicates high miscibility in this blend. A blend of PC/PMMA (50/50 wt/wt) shows two 1H T1p values, which are similar to those of the homopolymers PC and PMMA. These results indicate high immiscibility. The “domain size” calculated from NMR results of the miscible blend PC/PMCHM is approximately 40 Å. The results of DSC and TEM are similar to the NMR results. However, TEM results show the presence of 3% PC domains in the PC/PMCHM blend, which are not seen by NMR or DSC. Those PC domains are approximately 500 Å. A strong intramolecular repulsion in the copolymer PMCHM and specific intermolecular interactions between PC and PMMA may explain the miscibility in the PC/PMCHM system. © 1994 John Wiley & Sons, Inc.
Infrared spectroscopic studies of CO2 sorbed in glassy and rubbery polymeric membranes
Authors: Higuchi Akon , Nakagawa Tsutomu 
Published: April 2003

AbstractInfrared spectra of CO2 sorbed in rubbery and glassy polymers were measured to examine the relationships between the spectroscopic data and physical properties of the polymeric membranes. The “V‐shape” tendency in the plot of W1 [i.e., half‐width of CO2 peak sorbed in the membranes] vs glass‐transition temperature (Tg) is observed, and has exactly the same tendency that is widely known from the plot of log D (diffusion coefficient) vs Tg. It is suggested that the membranes having a wider W1 give a faster diffusion coefficient, since W1 is inversely related to the moment of inertia of CO2 in the membranes. Two distinct peaks of CO2 were not observed in the infrared spectra of CO2 sorbed in the glassy polymers. This suggests that the states of CO2 in the Henry mode and Langmuir mode in the glassy polymers are similar in the spectroscopic measurements. © 1994 John Wiley & Sons, Inc.
Phase behavior, morphology, and mechanical properties of polyethylene‐copolymer blends
Authors: Rhee J. , Crist B. 
Published: April 2003

AbstractBinary blends of unbranched polyethylene (PE) and 5‐10% model ethylene‐butene random copolymers are used to determine the effects of composition heterogeneity on phase separation in the melt, semicrystalline morphology, plane strain fracture toughness JC and tensile modulus and yield strength. Slowly cooled samples of melt‐miscible blends are appreciably tougher (JC = 5.2 kJ/m2) than unblended PE (JC = 2.7 kJ/m2). A blend with the same average short chain branch concentration, but which is phase separated in the melt state, has JC= 3.3 kJ/m2; dispersed domains of amorphous polymer have little effect on toughness. Enhanced toughness is associated with nonuniform morphology formed on slow cooling “one phase” melts composed of chains with different amounts of branching. The relative number of chemically different chains, as opposed to absolute branch concentrations, seems most important. Tensile properties are relatively unaffected by blending at these levels. Results from these model blends are used to consider the properties of compositionally heterogeneous ethylene copolymers. © 1994 John Wiley & Sons, Inc.
Association of hydrophobic counterions in aqueous solution of poly(allylammonium) chloride: Comparison between p‐n‐propylbenzenesulfonate and p‐iso‐propylbenzenesulfonate ions
Authors: Itaya Tomoyuki , Ochiai Hiroshi , Aoyama Tsuyoshi , Ueda Kazuyoshi , Imamura Akira 
Published: April 2003

AbstractThe hydrophobic association behavior of p‐propylbenzenesulfonate ions (n‐PBS− and iso‐PBS−) around poly(allylammonium) cation (PAAH+ was studied by absorption and 1H nuclear magnetic resonance (NMR) spectroscopy. In the presence of PAAH+Cl−, the broadening (hypochromism) of absorption band of PBS− were observed. In addition, all 1H NMR signals of PBS− exhibited up‐field shift which resulted from the intermolecular ring current shift. These results indicate the hydrophobic association of negative PBS− around PAAH+. The hydrophobic association arises from the accumulation of counterions around the polyion, and is stabilized by the hydrophobic interaction between propyl groups and the stacking interaction between benzene rings. The association of iso‐PBS− ions is rather weaker than that of n‐PBS−, suggesting that the steric hindrance of isopropyl groups prevents an effective association of hydrophobic counterions. Furthermore, through viscosity and Cl− activity measurements, it was found that the binding of associated PBS−,s to PAAH+ causes the change of its surroundings to hydrophobic character and its conformation. © 1994 John Wiley & Sons, Inc.
Refractive index and nonlinear optical properties of polyaniline derivatives
Authors: Chen Wen‐Chang , Jenekhe Samson A. , Meth Jeffrey S. , Vanherzeele Hermann 
Published: April 2003

AbstractAn investigation of the refractive index and third‐order nonlinear optical susceptibility χ(3)of two polypernigraniline derivatives, poly (4,4'‐diphenylimine methine) (PDPIM) and poly (4,4'‐diphenylimine p‐heptyloxybenzylidene) (PDPIHB) reveals effects of molecular structure on the linear optical and nonlinear optical properties of conjugated polymers. The χ(3)(−3ωω,ω,ω) of PDPIM was found to decrease relative to polypernigraniline, reflecting the observed decrease of the oscillator strength of the 2.2 eV absorption band when a methine carbon replaces one of the nitrogen atoms of pernigraniline repeat unti. The alkoxyphenylene side group substitution at the methine carbon in PDPIHB, however, significantly enhances the nonlinear optical response of PDPIHB while reducing the refractive index compared to PDPIM and polypernigraniline. The present results suggest that structural changes in conjugated polymers can be made in such a way as to enhance the nonlinear optical properties while modulating the linear optical properties. © 1994 John Wiley & Sons, Inc.