bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Coupling Agents on Melt Flow Behavior of Natural Fiber Composites
Authors: Hristov Velichko , Vlachopoulos John 
Published: May 2007

AbstractThe influence of coupling agents on the melt rheological properties of natural fiber composites has been investigated in this work using capillary and rotational rheometers. Scanning electron microscopy was also employed to supplement the rheological data. It was found that molecular weight and molecular weight distribution of the polymer matrix and coupling agent characteristics influence the filler wetting and the melt flow properties of the filled composites. Generally, low molecular weight and narrow molecular weight distribution polyethylene matrix provides relatively larger increase of the viscosity of the composites. Coupling agents tend to increase the resistance to shearing, but wall slip effects may interfere with the measured values, especially at very high filler loadings. Entrance pressure loss in capillaries is also influenced by polymer matrix and coupling agent used.magnified image
Mechanical Properties of Porous Polylactide/Chitosan Blend Membranes
Authors: Wan Ying , Wu Quan , Wang Sheng , Zhang Shengmin , Hu Zhilin 
Published: May 2007

AbstractPorous membranes were fabricated using chitosan and poly(DL‐lactide) or poly(L‐lactide) blends through a combinatorial technique. Well‐controlled porous structures could be achieved by optimizing processing conditions. The ductility and toughness of dry porous membranes were improved by incorporating an increased amount of chitosan, and the physical strength and dimensional stability of hydrated porous membranes were preserved if the components were used in a suitable ratio. Although there were measurable differences in the pore‐size distributions of membranes with the same composition prepared under identical conditions, this showed no effect in their dry states.magnified image
The Influence of the Irradiation Temperature on the Ratio of Chain Scission to Branching Reactions in Electron Beam Irradiated Polytetrafluoroethylene (PTFE)
Authors: Lappan Uwe , Geißler Uwe , Scheler Ulrich 
Published: May 2007

AbstractPolytetrafluoroethylene (PTFE) films have been irradiated by electron beam in vacuum at various temperatures ranging from room temperature up to temperatures far above the melting temperature. Changes of the chemical structure have been analyzed by 19F solid‐state NMR and IR spectroscopy. The concentration of several structures generated by irradiation increases with increasing irradiation temperature up to the beginning of the thermal degradation. The molar ratio of >CF branching points to CF3 end groups changes with crossing of the melting temperature. The generation of >CF branching points is accelerated if the PTFE is irradiated in the molten state, where branching reactions become more important.magnified image
Morphology and Properties of Poly(L‐Lactide) (PLLA) Filled with Hollow Glass Beads
Authors: Hu Xiao , Xu Hong‐Sheng , Li Zhong‐Ming 
Published: May 2007

AbstractThe morphology, crystalline behavior, and mechanical and thermal properties of poly(L‐lactide)/hollow glass beads (PLLA/HGBs) composites were investigated. The incorporation of HGBs enhanced the crystallization rate and crystallinity of PLLA, but slightly decreased its elongation at break. In addition, HGBs acted as stress concentration points inducing the plastic deformation of PLLA, leading to increased Izod impact strength. Differential scanning calorimetry results show that annealed PLLA eliminated cold crystallization phenomenon in the region of 100–140 °C and presented a double melting peak around 150 °C. Moreover, annealing was demonstrated to be effective for the improvement of tensile modulus, strength, Izod impact strength and heat distortion temperature of the composites due to the increased crystallinity and more perfect crystals. Silane coupling agents can enhance the interfacial adhesion of the composites, and lead to better mechanical properties. Compared to neat PLLA, the HGBs filled PLLA composites did not exhibit an obvious increase of the density.magnified image
Introduction of a New Coupling Agent for Selective Coupling of Hydroxy and Amino Group‐Containing Polymers
Authors: Jakisch Lothar , Komber Hartmut , Böhme Frank 
Published: May 2007

AbstractA new bifunctional coupling agent with an oxazinone and a lactamate group is synthesized. It is shown by means of model reactions that in the presence of aliphatic hydroxy compounds the reaction of the coupling agent is highly selective. At 220 °C, a conversion of the lactamate group of about 90% is observed under elimination of lactam. In a second reaction the oxazinone group is converted with an aliphatic amino compound. This high selectivity is utilized in the synthesis of segmented polyester/polyamide block copolymers by sequential conversion of the coupling agent with hydroxy‐terminated polyesters [poly(butylene terephthalate) (PBT) and polycaprolactone (PCL)] and amino‐terminated polyamide 12 (PA12) under the conditions of reactive extrusion. In the case of the PA12/PBT block copolymer, ductile behavior is observed, whereas the PA12/PCL block copolymer shows elastic properties. Both polymers are phase separated on the nanometer‐scale, as evidenced by AFM and SEM. The thermal behavior of the polymers is affected by the influence of the individual blocks.magnified image
Weighted Tent Spaces
Authors: Soria Javier 
Published: May 2007

AbstractWe generalize the theory of tent spaces introduced in [9] and [10], to consider weighted norms related to some function parameters (see [11]). We study their atomic decomposition, from which we obtain a weighted inequality for a certain fractional maximal operator. We also find the dual spaces, and get a new class of CARLESON measures and we identify the intermediate spaces when using several methods of interpolation.
Extensions of Unbounded Representations
Authors: Inoue Atsushi , Kurose Hideki , Ǒta Schǒichi 
Published: May 2007

AbstractInduced extensions of unbounded (non *‐preserving, in general) representations of a *‐algebra are studied and some elementary facts are shown. For further study of *‐representation of non‐commutative *‐algebra, we introduce twisted extensions of *‐representations as a generalization of induced extensions. And we show that the SCHRÖDINGER representation of a WEYL‐algebra can be realized as a twisted extensions for any its *‐subrepresentation.
Über die Veränderung konformer Gebietsgrößen bei quasikonformer Abbildung
Authors: Kirsch Siegfried 
Published: May 2007

AbstractEs wird ein neuer Typ von Extremalproblemen bei quasikonformen Abbildungen behandelt, bei denen das zugehörige quadratische Differential eine stückweise analytische Funktion darstellt.Für eine spezielle Klasse quasikonformer Abbildungen wird ein Verfahren vorgestellt, das zu asymptotisch scharfen Abschätzungen der Funktionalwerte führt, falls die Dilatation der quasikonformen Abbildungen nur wenig von 1 abweicht.
A New Integral Geometric Formula of the Blaschke‐Petkantschin Type
Authors: Vedel Jensen E. B. , Kiê K. 
Published: May 2007

AbstractRecently, a new geometric measure decomposition has been derived by Zähle (1990), involving the r‐fold product of the d‐dimensional Hausdorff measure with itself. The application to moment measure estimation has been discussed in Jensen et al. (1990a) and Zähle (1990). The decomposition involves, in essence, the rotational invariant measure on r‐dimensional linear subspaces in Rn and the r‐fold product of the (d ‐ n + r)‐dimensional Hausdorff measure. In the present paper, we derive another decomposition of this type, involving linear subspaces containing a fixed lower‐dimensional linear subspace. The formula has applications in geometric sampling.
A Coarea Formula for Multiple Geometric Integrals
Authors: Kiêu K. 
Published: May 2007

AbstractThe coarea formula by Federer (1969) is a general transformation formula for simple geometric integrals. In the present paper, we derive a coarea formula for multiple geometric integrals. The construction of this new formula is based on the use of the simple coarea formula on a product of Hausdorff rectifiable sets. Also, this coarea formula for multiple integrals is extended, so it can be applied to the locally Hausdorff rectifiable sets described in Zähle (1982). An application of the formula resulting in new Blaschke‐Petkantschin formulae is presented in Jensen and Kiêu (1991).
Some Characterizations of Ergodic Probability Measures
Authors: Adamski Wolfgang 
Published: May 2007

AbstractLet P be a Markov kernel defined on a measurable space (X, 𝒜). A P‐ergodic probability is an extreme point of the family of all P‐invariant probability measures on 𝒜. Several characterizations of P‐ergodic probabilities are given. In particular, for the special case of a topological space X both P‐ergodic Baire probabilities and P‐ergodic Borel probabilities with additional regularity properties are characterized.
Über ein Extremalproblem bei im Mittel quasikonformen Abbildungen
Authors: Kirsch Siegfried 
Published: May 2007

AbstractEs werden notwendige Bedingungen, eine hinreichende Bedingung und ein Unitätskriterium für Extremalfunktionen zu einem Extremalproblem bei Q(z)‐quasikonformen Abbildungen angegeben, deren Dilatation im Mittel beschränkt ist und auf einer vorgegebenen Teilmenge nur vorgeschriebene Werte annimmt. Die Anwendung der hinreichenden Bedingung zur Konstruktion von Extremalfunktionen wird an Beispielen demonstriert.
Central Limit Theorems for Markov‐Connected Random Variables
Authors: Liebscher E. 
Published: May 2007

AbstractThe paper provides some central limit theorems for triangular arrays of Markov‐connected random variables. It is assumed the Markov chain to satisfy condition (D1) which is an generalization of strong Doeblin's condition (Do). One result represents a central limit theorem without the assumption of finite variances.
Kernel Properties and Representations of Boundary Integral Operators
Authors: Schwab C. , Wendland W. L. 
Published: May 2007

AbstractBoundary integral operators arise in the reduction to the boundary method for solving elliptic boundary value problems. These are classical pseudodifferential operators of integer order on the boundary. In order to exploit these boundary integral operators for computational methods one needs explicit knowledge of the corresponding kernel properties in the framework of Hadamard finite part regularization, explicit representation based on local polar coordinates and explicit transformation under the change of the parametric representation of the boundary manifold. Here we present these properties for the special case of a (piecewise) smooth two‐dimensional boundary surface immersed into ℝ3.
Boundedly Compatible Webs and Strict Mackey Convergence
Authors: Gilsdorf Thomas E. 
Published: May 2007

AbstractWe look for characterizations of those locally convex spaces that satisfy the strict Mackey convergence condition within the context of spaces with webs. We will say that a locally convex space has a boundedly compatible web if it has a web of absolutely convex sets whose members behave like zero neighborhoods in a metrizable locally convex space. It will be shown that these locally convex spaces satisfy the strict Mackey convergence condition. One consequence of this result will be a characterization of boundedly retractive inductive limits. We will also prove that if E is locally complete and webbed, then the strict Mackey convergence condition is equivalent to E having a boundedly compatible web.
Toward a Unified Theory of Generalized Functions: Convergence
Authors: Mikusiński Piotr , Taylor Michael D. 
Published: May 2007

AbstractGeneralized functions are usually treated as bounded linear functionals on spaces of test functions. Here they are considered as objects which „convolute”︁ with test functions and satisfy a certain associativity condition. In this setting simple definitions are given for convergence of sequences of test functions and generalized functions, definitions which do not depend on particular properties of the space of test functions. It is shown that for the most commonly used spaces, these general definitions reduce to the standard ones.
A Note on the Type of Local von Neumann Algebras in Quantum Field Theory over Curved Space‐time
Authors: Wollenberg Manfred 
Published: May 2007

AbstractIt is shown that there are relations between the Connes invariant for local v. Neumann algebras belonging to different curved space‐times provided these local algebras are connected by a certain asymptotic condition. This asymptotic condition is implied by a scaling limit condition as well as by a condition of connectedness by large translations.
Generalized Brownian Motion, Point Processes and Stochastic Calculus for Random Fields
Authors: Fichtner K.‐H. , Winkler G. 
Published: May 2007

AbstractA representation of the Malliavian derivative and the Skorochod integral in terms of random point systems on Polish spaces (and thus generalizing from the unit interval) is derived. This leads to a stochastic calculus based on random point systems. The operators are given explicitely and in a simple form allowing concrete probabilistic and quantum probabilistic interpretations.
Construction of Corner Singularities for Agmon‐Douglis‐Nirenberg Elliptic Systems
Authors: Costabel Martin , Dauge Monique 
Published: May 2007

AbstractCorner singularities in plane domains are characterized by certain singular exponents and angular functions. Our construction of singularities is based on two Cauchy integrals at two different levels of symbolic calculus. This construction yields new information about the angular functions and also more explicit formulas for the computation of the singular exponents.
Ergänzungsgesetze
Authors: Burde Klaus 
Published: May 2007

AbstractFür rationale Primzahlen p, q mit q  1(pk) wird unter der Voraussetzung, daß p zumindest pk‐1‐ter Potenzrest modulo q ist, in §2 ein Kriterium dafür hergeleitet, daß p ein pk‐ter Potenzrest modulo q ist. Solche Kriterien wurden für k = 1 und beliebiges p von ANKENY in [1] sowie von Muskat in [8] und [9] angegeben. Für p = 2 und beliebiges k bewies Evans in [6] ein entsprechendes, von Muskat in [10] vermutetes Kriterium. Das hier aufgestellte Kriterium (2.10), (2.10') stimmt für k = 1 mit dem von ANKENY überein, hat für p = 2 jedoch eine andere Form als das von Muskat‐Evans.In einem vorbereitenden §1 wird der zur Herleitung unseres Kriteriums geeignete Rechenbereich vorgestellt, §3 enthält Auswertungsbeispiele. Einige für das Verständnis nicht wesentliche Beweise sind in einem Anhang zusammengestellt, auf den mit A* verwiesen wird.
Symmetry Groups of Coloured Graphs
Authors: Baumann Ulrike 
Published: May 2007

AbstractA perfect colouring Φ of a simple undirected connected graph G is an edge colouring such that each vertex is incident with exactly one edge of each colour. This paper concerns the problem of representing groups by graphs with perfect colourings. We define groups of graph automorphisms, which preserve the structure of the colouring, and characterize these groups up to isomorphism. Our considerations are based on the fact that every perfectly coloured graph is isomorphic to a Schreier coset graph on a group generated by involutions.
On Colouring Partial Joins of a Complete Graph and a Cycle
Authors: Stiebitz M. , Wessel W. 
Published: May 2007

AbstractDefine the partial join of two graphs to be some graph arising from their disjoint union by adding a set of new edges each joining a vertex of the first graph and a vertex of the second one. We characterize all colour‐critical graphs being partial joins of a complete graph and an odd cycle thus completely answering a special case of a question raised by T. GALLAI in 1969.
Analysis of a Distinguished Laplacian on Solvable Lie Groups
Authors: Giulini Saverio , Mauceri Giancarlo 
Published: May 2007

AbstractWe study a class of kernels associated to functions of a distinguished Laplacian on the solvable group AN occurring in the Iwasawa decomposition G = ANK of a noncompact semisimple Lie group G. We determine the maximal ideal space of a commutative subalgebra of L1, which contains the algebra generated by the heat kernel, and we prove that the spectrum of the Laplacian is the same on all Lp spaces, 1 ≤ p < ∞. When G is complex, we derive a formula that enables us to compute the Lp norm of these kernels in terms of a weighted Lp norm of the corresponding kernels for the Euclidean Laplacian on the tangent space. We also prove that, when G is either rank one or complex, certain Hardy‐Littlewood maximal operators, which are naturally associated with these kernels, are weak type (1, 1).
Modular Interval Spaces
Authors: Bandelt H.‐J. , van de Vel M. , Verheul E. 
Published: May 2007

AbstractModular interval spaces represent a common generalization of Banach spaces of type L1(μ) or B(X), of hyperconvex metric spaces, modular lattices, modular graphs, and median algebras. It turns out that several types of structures are susceptible for a notion capturing essential features of modularity in lattices, e.g., semilattices, multilattices, metric spaces, ternary algebras, and graphs. There is no perfect correspondence between modular structures of various types unless the existence of a neutral point is imposed. Modular structures with neutral points embed in modular lattices. Particular modular interval spaces (e.g., median spaces, or more generally, modular spaces in which intervals are lattices) can be characterized by forbidden subspaces.
Besov Spaces of M‐harmonic Functions on Bounded Symmetric Domains
Authors: Hahn K. T. , Youssfi E. H. 
Published: May 2007

AbstractNew Besov spaces of M‐harmonic functions are introduced on a bounded symmetric domain in ℂn. Various characterizations of these spaces are given in terms of the intrinsic metrics, the Laplace‐Beltrami operator and the action of the group of the domain.
Some Further Properties of Kählerian Twistor Spinors
Authors: Kirchberg K.‐D. 
Published: May 2007

AbstractOn a spin Kähler manifold M2m a new first integral QΨ of the Kählerian twistor equations is presented. If the scalar curvature has a critical point then QΨ vanishes. In case M2m is closed, this fact provides a simple geometrical obstruction for Kählerian twistor spinors and, consequently, some new vanishing theorems. Twistor spinors with QΨ ≠ 0 are investigated. Some invariants of the corresponding space of twistor spinors are constructed if the other basic first integral CΨ does not vanish, too. Each twistor spinor Ψ with CΨ ≠ 0 and QΨ ≠ 0 determines a foliation of M2m whose leaves are totally geodesic immersed Kähler manifolds. It is shown that Kählerian twistor spinors of type (r, s) can be interpreted as the minima of a certain functional. Some properties of Kählerian twistor spinors of the exceptional type r = (m + 2)/2 are proved.
On Lyapunov Exponents and Rotation Number of Random Linear Hamiltonian Systems
Authors: Teichert Heidrun 
Published: May 2007

AbstractWe consider linear Hamiltonian differential systems in R2n depending on a stationary ergodic Markov process. The induced processes on the Lagrangian manifolds Lp and Lp−1, p (1 ≦ p ≦ n) are studied. From this we derive representations for the Lyapunov exponents, especially the lowest non‐negative exponent, and a (suitably defined) rotation number of the system.
Stability and Convergence of a Hyperbolic Tangent Method for Singular Integral Equations
Authors: Venturino Ezio 
Published: May 2007

AbstractIn this paper we reexamine a previously proposed quadrature scheme, [VENTURINO], based on a formula proposed in [STENGER, 1976]. Our goal is to establish a stability result for the dominant singular integral equation of index one, and from it derive the error analysis for the proposed numerical method. The convergence of the method can then be extended to the first kind complete equation and to the equation of index zero. Finally the modifications necessary for applying this analysis to a recently proposed scheme for Hadamard finite part integral equations are examined. In all these proofs the necessary assumption we need to make is to restrict our considerations to a compact subset of the interval in which the equation is formulated, containing all the nodes where the unknown is evaluated.
Real Analytic Fibre Bundles: Some Results on Classification and Homotopies
Authors: Guaraldo F. 
Published: May 2007

AbstractThe classification problem for holomorphic fibre bundles over Stein spaces was solved by H. GRAUERT. Along the same lines, the real coherent analytic case was considered by A. TOGNOLI and V. ANCONA.In this paper we propose a different approach, based on classifying spaces, in order to study the previous problem for real analytic fibre bundles over C‐analytic subspaces of Rm.So, let X be a C‐analytic subspace of Rm and G a compact Lie group. The main result is a characterization of the real analytic G‐principal fibre bundles over X for which the analytic and topological equivalence coincide.Moreover, we prove that these bundles can be classified also by means of homotopy classes of analytic maps of X into classifying spaces.Among the others results, are worth recording: a relative approximation theorem of continuous cross sections by analytic ones, a theorem about the equivalence between analytical and topological homotopy between cross sections and a covering homotopy theorem.
On the Existence of Radial Solutions of a Nonlinear Elliptic BVP in an Annulus
Authors: Cheng Yuanji 
Published: May 2007

AbstractIn this paper we study the radial solutions of quasilinear elliptic BVP:

on A, u satisfies the Robin boundary conditions (2) below, where A = {x∈Rn; a1 < |x| < a2}, a2 > a1 > 0, constants. Under the very general conditions, we prove that if f is superlinear at u = ∞, then (*) admits infinitely many radial solutions, and that each of them has a different (finite) number of zeros.
The Conformal Arclength Functional
Authors: Musso Emilio 
Published: May 2007

AbstractA generic smooth curve of the three dimensional Möbius space admits a natural parameter (or conformal arclength). Integrating the conformal arclength we get a conformally invariant variational problem. In the present paper we study the extremal curves of this variational problem. We derive the associated Euler‐Lagrange equations and we get the natural equations of the extremal curves. The natural equations are integrated and the explicit solutions are given.
Some Remarks on Krein's Extension Theory
Authors: Brasche J. F. , Neidhardt H. 
Published: May 2007

AbstractThe extension problem of semibounded symmetric operators and symmetric operators with a gap is studied in detail. Using a suitable representation (Krein model) for the inverses of those operators a parameterization of their symmetric and self‐adjoint extensions is introduced which improves Krein's famous extension theory. In particular, the parameterization clearly shows which self‐adjoint extensions in the gap case correspond to Friedrichs and v. Neumann or Krein extensions in the semibounded case. Moreover, special properties of the extensions as the exactness of the gap are characterized in terms of the parameters.
On the Spectral Flow of Families of Dirac Operators with Constant Symbol
Authors: Bunke Ulrich 
Published: May 2007

AbstractWe consider families of generalized Dirac operators Dt with constant principal symbol and constant essential spectrum such that the endpoints are gauge equivalent, i.e., D1 = W*D0W. The spectral flow un any gap in the essential spectrum we express as the Fredholm index of 1 + (W ‐ 1)P where P is the spectral projection on the interval d, ∞) with respect to D0 and d is in the gap. We reduce the computation of this index to the Atiyah‐Singer index theorem for elliptic pseudodifferential operators. We find an invariant of the Riemannian geometry for odd dimensional spin manifolds estimating the length of gaps in the spectrum of the Dirac operator.