bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the asymptotic behavior of the eigenvectors of large banded Toeplitz matrices
Authors: Böttcher A. , Grudsky S. , Ramírez de Arellano E. 
Published: December 2005

AbstractLet λ be an eigenvalue of an infinite Toeplitz band matrix A and let λn be an eigenvalue of the n ×n truncation An of A . Suppose λn converges to λ as n → ∞. We show that generically the eigenspaces for λn are onedimensional and contain a vector xn whose first component is 1 if only n is large enough, and we prove that xn converges to an eigenvector x 0 of A that is independent of the particular choice of the λn . The eigenspace of A corresponding to λ is spanned by x 0 and a finite number of shifts of x 0. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Density of C∞(Ω) inW1,p (x )(Ω) with discontinuous exponent p (x )
Authors: Fan Xianling , Wang Suyun , Zhao Dun 
Published: December 2005

AbstractIn this paper, we present a sufficient condition for the density of C ∞(Ω) inW 1,p (x )(Ω) with p (x ) being discontinuous. Roughly speaking, we can get the density under the following assumptions: 1) Ω can be divided into some open pieces Ωi such that p (x ) is “fine”on each Ωi , for example, p (x ) satisfies the Dini–Lipschitz condition on each Ωi . 2) The corresponding pieces “get along with each other regularly ”. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The international drivers of domestic airline mergers in twenty nations: integrating industrial organization and international business
Authors: Clougherty Joseph A. 
Published: December 2005

AbstractThe domestic airline merger phenomenon of the late 1980s and early 1990s sparked a great deal of Industrial Organization (IO) literature; yet, that literature neglected non‐US domestic mergers and potential for international competitive gains. Using an International Business perspective to complement an IO analysis, I argue that factoring international competitive incentives helps explain domestic airline merger activity. A Cournot model of airline competition illustrates that domestic mergers, via enhanced domestic networks and reduced domestic competition, generate international competitive gains. Further, empirical tests—using a structural equations approach on panel data covering interhyphen‐national city‐pair market segments—support domestic mergers improving international competitiveness. Copyright © 2006 John Wiley & Sons, Ltd.
Lower bounds for the relative greedy algorithm for approximating Steiner trees
Authors: Hougardy Stefan , Kirchner Stefan 
Published: December 2005

AbstractThe Steiner tree problem is to find a shortest subgraph that spans a given set of vertices in a graph. This problem is known to be NP‐hard, and it is well known that a polynomial time 2‐approximation algorithm exists. In 1996, Zelikovsky suggested an approximation algorithm for the Steiner tree problem that is called the relative greedy algorithm. Until now the performance ratio of this algorithm has not been known. Zelikovsky provided 1.694 as an upper bound, and Gröpl, Hougardy, Nierhoff, and Prömel proved that 1.333 is a lower bound. In this article we improve the lower bound for the performance ratio of the relative greedy algorithm to 1.385. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 47(2), 111–115 2006
Physical and mechanical properties of pultruded composites containing fillers and low profile additives
Authors: Boukhili R. , Boukehili H. , Daly H. Ben , Gasmi A. 
Published: December 2005

AbstractThis article deals with the effect of fillers and additives content on the physical and mechanical properties of unidirectional pultruded glass/polyester composites. The physical characterization consisted of determining the void volume fraction (Vv), density, shrinkage ratio, coefficient of thermal expansion (CTE), and dynamic mechanical properties. The mechanical tests consisted of three‐point‐bending tests under static, impact, and fatigue loading. The low profile additive (LPA) has been found to compensate the cure shrinkage by microvoid formation. Dynamic mechanical analysis measurements show that the LPA slightly lowers the glass transition temperature Tg and increases the internal damping Tan δ. The transverse coefficient of thermal expansion was found to be sensitive to the LPA content. Three‐point bending tests show that the interlaminar shear strength (ILSS) is slightly sensitive to the fillers and LPA content, but the flexural strength is not affected. Impact test results on short beam shear and flexural specimens show the same behavior as in the static tests except that the LPA content has a detrimental effect on the flexural impact properties. The fatigue tests performed show that the effect of fillers is not significant, while the LPA effect is mixed. It seems that there is an LPA content for which the fatigue resistance is maximized. Finally, the wide range of behaviors and span‐to‐depth ratios investigated suggest that the ILSS as measured according to the ASTM 2344 recommendations can be largely misleading because of the unavoidable compressive yielding under the loading nose. For the materials investigated, higher span‐to‐depth ratio are more representative of the ILSS. POLYM. COMPOS., 27:71–81, 2006. © 2005 Society of Plastics Engineers
Synthesis and properties of poly(methyl methacrylate)/clay nanocomposites using natural montmorillonite and synthetic Fe‐montmorillonite by emulsion polymerization
Authors: Kong Qinghong , Hu Yuan , Yang Ling , Fan Weicheng , Chen Zuyao 
Published: December 2005

AbstractIn this article, Fe‐montmorillonite (Fe‐MMT) was synthesized by hydrothermal method. For the first time, Fe‐MMT was modified by cetyltrimethyl ammonium bromide (CTAB), and poly(methyl methacrylate)(PMMA)/Fe‐MMT nanocomposites were synthesized by emulsion polymerization. Then poly(methyl methacrylate)(PMMA)/natural montmorillonite (Na‐MMT) and PMMA/Fe‐MMT nanocomposites were compared by Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). By XRD and TEM, it was found out that the morphology of PMMA/Fe‐MMT nanocomposites was different from that of the PMMA/Fe‐MMT nanocomposites when the content of two types of clay was same in the PMMA matrix. It was possible that the presence of iron may lead to some radical trapping, which enhances intragallery polymerization to be developed to improve layer dispersion in PMMA/Fe‐MMT systems. In TGA curves, the thermal stability and residue at 600°C of PMMA/Fe‐MMT nanocomposites were higher than those of PMMA/Na‐MMT nanocomposites. Those dissimilarities were probably caused by structural Fe ion in the lattice of Fe‐MMT. POLYM. COMPOS., 27:49–54, 2006. © 2005 Society of Plastics Engineers
Finite element approach to composite mold design based on Darcy flow with velocity clipping
Authors: Turner D.Z. , Nakshatrala K.B. , Hjelmstad K.D. 
Published: December 2005

AbstractThis article discusses various numerical techniques that are widely used in industry to solve the Darcy flow equations. We outline their merits and limitations. We also present a new stabilized finite element formulation that has been proposed recently (Nakshatrala et al., Comput. Meth. Appl. Mech. Eng., doi: 10.1016/j.cma.2005.07.009). This method is the best available numerical method in the present literature for solving Darcy flow equations and it is the ideal formulation for three‐dimensional Darcy flow simulations because of its accuracy and stability characteristics. This formulation can be easily implemented in an existing finite element code and it is the only formulation based on continuous finite elements to pass three‐dimensional constant flow patch tests. Next, we present a computational methodology that is based on a velocity clipping finite element approach and a steady‐state solution of the Darcy flow equations to model and visualize resin flow during the resin transfer molding process. We show that steady‐state Darcy flow can be a valuable tool for a composite manufacturer to decide on the location of the inlets and outlets, and also to visualize resin flow. The methodology is promising for the design of the manufacturing process for complex composite members because it is computationally efficient. We also present a novel approach to model open space within the mold that results from cutting and bending of fibers. In the end, we provide some experimental results and compare them with the numerical results. POLYM. COMPOS., 27:65–70, 2006. © 2005 Society of Plastics Engineers
Preparation, characterization, and properties of poly(vinyl chloride)/organophilic‐montmorillonite nanocomposites
Authors: Ren Tianbin , Yang Jun , Huang Yanxia , Ren Jie , Liu Yan 
Published: December 2005

AbstractPoly(vinyl chloride) (PVC)/organophilic‐montmorillonite (OMMT) nanocomposites were prepared by direct melt intercalation. PVC/compatibilizer ((vinyl acetate) copolymer (VAc))/OMMT nanocomposites were also prepared by melt intercalation by a masterbatch process. The effect of OMMT content on the nanostructures and properties of nanocomposites was studied. The nanostructures were studied by wide angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). The linear viscoelastic properties and dynamic mechanical properties of PVC/OMMT nanocomposites were also investigated by an advanced rheometric expansion system (ARES) rheometer. The results showed that partially exfoliated and partially intercalated structures coexisted in the PVC/OMMT and PVC/VAc/OMMT nanocomposites. The mechanical properties test results indicated that the notched Charpy impact strengths of nanocomposites were improved compared to that of pristine PVC and had a maximum value at 1 phr OMMT loadings. The compatibilizer could further improve the impact strengths. But the existence of OMMT decreased the thermal stability of PVC/OMMT and PVC/VAc/OMMT nanocomposites. The linear viscoelastic properties test results indicated the dependence of G′ and G″ on ω shows nonterminal behaviors, and they had better processibility compared with pristine PVC. However, the glass transition temperatures of PVC/OMMT nanocomposites almost had little change compared to that of pristine PVC. POLYM. COMPOS., 27:55–64, 2006. © 2005 Society of Plastics Engineers
Investigation of basalt fiber composite mechanical properties for applications in transportation
Authors: Liu Qiang , Shaw Montgomery T. , Parnas Richard S. , McDonnell Anne‐Marie 
Published: December 2005

AbstractNew materials offer the promise of innovative applications in transportation. One such new material is basalt fiber, which is used in other industries because of documented strengths [Ramakrishnan et al., “Performance Evaluation of 3‐D Basalt Fiber Reinforced Concrete and Basalt Rod Reinforced Concrete,” NCHRP‐IDEA Program Project Final Report, Transportation Research Board, Washington, DC, 1998]. Use in transportation, however, requires a better knowledge of many properties. This article discusses initial work with basalt‐reinforced polymer composites. Polymer composites reinforced by basalt fabric and glass fabrics were produced for these tests. Void content below 3% were measured for all the composites produced for the testing program. No significant differences in Young's modulus, tensile strength, flexure strength, shear strength, and compression strength were found between basalt composites and glass composites. Environmental durability testing of basalt composites is ongoing. POLYM. COMPOS. 27:41–48, 2006. © 2005 Society of Plastics Engineers
Modeling of fiber–polymer coupling for suspensions of mono‐modal fibers
Authors: Huq A.M.A. , Azaiez J. 
Published: December 2005

AbstractThe rheology of suspensions of fibers in polymer solutions is strongly dependent on fiber–fiber and fiber–polymer interactions. To model these interactions and their dependence on the flow and suspension properties, the steady shear viscosity of glass fibers in a polyethylene oxide polymer solution are measured for different fiber volume fractions and aspect‐ratios. The measurements are conducted for well characterized fiber samples that have a uniform and well defined aspect‐ratio and for moderate volume fractions. The results of the experimental study are used to correlate the polymer–fiber coupling factor and the fiber–fiber interaction coefficient using a mathematical model based on a modified FENE‐P (finitely extensible nonlinear elastic) constitutive equation. It was found that both parameters are strongly dependent on the characteristics of the suspension, but also depend on the flow shear rate that determines the degree of fiber orientation. In general, fiber–fiber and polymer–fiber interactions increase with both the aspect‐ratio and the volume fraction and are more important when the fibers are not fully oriented. POLYM. COMPOS., 27:82–91, 2006. © 2005 Society of Plastics Engineers
Wear behavior of carbon fiber‐reinforced poly(phenylene sulfide)
Authors: Quintelier J. , Samyn P. , De Baets P. , Tuzolana T. , Van Paepegem W. , Van den Abeele F. , Vermeulen J. 
Published: December 2005

AbstractOn a pin‐on‐disc test rig, online measurements of the wear and friction of steel sliding against carbon fiber‐reinforced polyphenylene sulfide were done. Instead of the standard set‐up, a rotating composite disc and steel pin are used. The frictional behavior of this material pair results in a friction coefficient of 0.33, while a carbide film is formed in the wear track. This results in the lowering of the frictional behavior. The wear rate is rather low, but when the wear track is covered with a carbide film, suddenly the wear rate raises. This is not due to the wear of the composite material but only as a result of the start of terrible wear of the steel counter face. Moreover, the wear of the pin is strongly related to the wear track. The pin is flattened at the sides of the formed wear track, but in contact with the carbide film there is less wear, resulting in a pin with two flat sides, making contact with the original surface, and a rig in the middle of the pin following the roundness of the wear track. The frictional behavior is strongly dependent on the weft‐warp direction. POLYM. COMPOS., 27:92–98, 2006. © 2005 Society of Plastics Engineers
Joining of fiber‐reinforced polymer tubes for high‐pressure applications
Authors: Mertiny P. , Ellyin F. 
Published: December 2005

AbstractFiber‐reinforced polymer composites offer superior performance particularly in harsh environments; hence, they are recognized as an attractive material, especially for the transportation of pressurized fluids. However, an extensive use of these composites has been hampered, in part due to unsatisfactory solutions for the joining of subcomponents, and insufficient knowledge on the associated damage behavior. A favorable connection design for a piping system can be an adhesively bonded joint. In this study, a unique adhesive injection technique is presented that joins composite pipe sections using filament‐wound overlap sleeve couplers. The purpose of the present study was to characterize the performance and associated damage behavior of a prototype‐size pipe structure joined by the above procedure. Internal pressure and axial traction were applied to specimens at various biaxial ratios. In addition to the experimental investigation, the joint geometry was also modeled numerically employing the finite element technique. This yielded a better understanding of the damage behavior and enabled a parametric study that provided recommendations for an improved joint design. POLYM. COMPOS., 27:99–109, 2006. © 2005 Society of Plastics Engineers
Validity of asthma diagnoses recorded in the Medical Services database of Quebec
Authors: Blais Lucie , Lemière Catherine , Menzies Dick , Berbiche Djamal 
Published: December 2005

AbstractThe goal of this study was to evaluate the validity of asthma diagnoses recorded in the Medical Services (physician billing) database of the Canadian province of Quebec. The predictive positive value (PPV) and predictive negative value (PNV) of two operational definitions of asthma based on diagnoses recorded in the database were evaluated. Patients 16–80 years old treated by a respiratory or a family physician in 2002 were selected from the database. The diagnosis derived from the Medical Services database was compared to the diagnosis written in the patient's medical chart. The PPV and PNV of the first operational definition based on one asthma diagnosis or more recorded in the database over a 1‐year period were found to be 0.75 and 0.96 for respiratory physicians and 0.67 and 0.99 for family physicians, for patients 16–44 years old. The PPV increased to 0.78 for family physicians and to 0.77 for respiratory physicians when the second operational definition based on two diagnoses of asthma or more was used. Results tended to be lower for 45–80 years old patients. We conclude that diagnoses recorded in the Medical Services database of Quebec are valid to identify patients with asthma. Copyright © 2005 John Wiley & Sons, Ltd.
Flexible supercritical CO2‐assisted process for poly(methyl methacrylate) structure formation
Authors: Reverchon E. , Rappo E. Schiavo , Cardea S. 
Published: December 2005

AbstractPoly(methyl methacrylate) membranes have been prepared using a supercritical fluid‐phase inversion process in which CO2 acts as the nonsolvent. Series of experiments were performed at various polymer concentrations, temperatures, and pressures using three different solvents, dimethylsulfoxide, acetone, and tetrahydrofuran. We operated at polymer concentrations ranging between 25 and 1% (w/w) in DMSO, acetone, and THF, obtaining membranes that change with continuity from cellular structure to a structure formed by networked microparticles. The membrane formation parameters in the case of DMSO and acetone have also been varied between 15 and 25 MPa and between 35 and 65°C. We observed that on increasing the pressure and decreasing the temperature, the cell size decreased. The influence of the solvent used on membrane formation has also been analyzed. On increasing the mutual affinity between solvent and nonsolvent, cell and pore sizes decrease and the structure changes from nearly closed to open interconnected cells. POLYM. ENG. SCI. 46:188–197, 2006. © 2005 Society of Plastics Engineers
Kinetic analysis of thermo‐oxidative degradation of PEEK/thermotropic liquid crystalline polymer blends
Authors: Naffakh M. , Gómez M.A. , Marco C. , Ellis G. 
Published: December 2005

AbstractThe thermal degradation behavior of blends of poly(aryl ether ether ketone), PEEK, with a thermotropic liquid crystalline polymer (TLCP), Vectra®, were investigated in an oxidative atmosphere, using thermogravimetric analysis under dynamic conditions. The theoretical weight loss curves of the blends were compared with the experimental curves in order to explain the effect of blending on the thermal stability of the pure polymers. The thermo‐oxidative degradation of PEEK/Vectra® blends of different compositions takes place in various steps and the characteristic degradation temperatures and the kinetic parameters such as activation energy are strongly influenced by blending. Polymer blends based on this TLCP polymer had not been previously studied from kinetic viewpoint. POLYM. ENG. SCI. 46:129–138, 2006. © 2005 Society of Plastics Engineers
The local thermomechanical conditions and the fracture behavior of an injection‐molded poly(oxymethylene)
Authors: Viana J.C. 
Published: December 2005

AbstractThis work explores the fracture behavior of an injection‐molded engineering thermoplastic, poly(oxymethylene), POM. Lateral gated discs of 120 mm diameter and 1.5 mm thick were molded with variations of the melt temperature and injection flow rate. The local thermomechanical environment was characterized by computer simulations of mould filling phase. This also allows the computation of two thermomechanical indices related to the morphological state of the moldings. From the molded discs, double edge notched tensile (DENT) specimens were meticulously cut at different angles with respect to the flow direction and with distinct ligament lengths. The fracture tensile tests were performed at 2 mm/min at controlled room temperature. As the test configuration (specimen geometry) imposes a plane stress state, the stress intensity factor, KI, was calculated as function of the processing conditions and orientation angle with respect to the flow direction. The KI values and their degree of anisotropy are dependent upon processing conditions. Finally, the dependences of KI values upon the thermomechanical indices (and therefore on the expected morphological state of the moldings) are established. POLYM. ENG. SCI. 46:181–187, 2006. © 2005 Society of Plastics Engineers
Structure and mechanical properties of compatibilized poly(ethylene terephthalate)/poly(ethylene octene) blends
Authors: Guerrica‐Echevarría G. , Eguiazábal J.I. , Nazábal J. 
Published: December 2005

AbstractPoly(ethylene terephthalate) (PET) based blends were obtained by melt blending PET with up to 30 wt% poly(ethylene‐octene) either modified with maleic anhydride (mLLDPE) or not (LLDPE). Both PET/LLDPE and PET/mLLDPE blends were immiscible. The dispersed phase particle size was large in LLDPE blends, but upon mLLDPE addition, it decreased to a small (submicron) and rather constant value with composition. This indicated compatibilization, and was attributed to specific interactions between the ester and maleic groups of PET and mLLDPE, respectively, rather than grafting reactions between components. Linear decreases in Young's modulus and yield stress, and ductility increases were observed in blends with mLLDPE. Super‐toughness was achieved in blends with mLLDPE, which took place when the critical interparticle distance (IDc) was below 0.17 μm and with only half the cross section of the specimens broken. The IDc of these blends and those of other blends from bibliography were compared with the adhesion levels estimated from the expected main interactions between the components of the blends. This comparison strongly indicated that, at least through an adhesion range, IDc depends on the adhesion level, and that IDc decreases as the adhesion level increases. POLYM. ENG. SCI. 46:172–180, 2006. © 2005 Society of Plastics Engineers
Novel aromatic polyimide fiber with biphenyl side‐groups: Dope synthesis and filament internal morphology control
Authors: Liu Xiangyang , Xu Wei , Ye Guangdou , Gu Yi 
Published: December 2005

AbstractA new organic‐soluble aromatic polyimide with biphenyl side‐groups has been synthesized from 4,4′‐oxydiphthalic anhydride and 3,5‐diamino‐benzonic‐4′‐biphenyl ester (DABBE) via a one‐step polymerization in m‐cresol. A higher molecular weight polyimide has been obtained by the addition of chlorotrimethylsilane (TMSCl) in the solution of DABBE to form, in situ, silylated diamine. The optimum mole amount of TMSCl relative to the number of amino groups is 100%. This polyimide is soluble in m‐cresol, allowing fibers to be spun from isotropic solution using a dry‐jet wet spinning method. Based on a ternary phase diagram of m‐cresol, ethanol, and water, controlling of the internal morphology of as‐spun fibers has been achieved by varying the rate of polyimide coagulation through adjustment of nonsolvent/solvent miscibility in the coagulation bath. Scanning electron microscopic pictures show that filament internal morphologies ranged from porous‐like to fully solid. The solid as‐spun fibers can be drawn at high temperatures (>330°C) under tension to high drawn ratios (up to 6×), which produces a remarkable increase in tensile strength to about 1.0 GPa and an initial modulus higher than 60 GPa. POLYM. ENG. SCI. 46:123–128, 2006. © 2005 Society of Plastics Engineers