bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallization studies of poly(trimethylene terephthalate) using thermal analysis and far‐infrared spectroscopy
Authors: Vasanthan Nadarajah , Yaman Mustafa 
Published: May 2007

AbstractCrystallization of poly(trimethylene terephthalate) (PTT) by annealing was examined using density measurement, differential scanning calorimetry, and far‐infrared spectroscopy (FIR). Crystallinity, measured by density, increased slowly up to the Ta of 185 °C and increases rapidly once Ta exceeds 185 °C. It was found that thermally induced crystallization is mainly temperature‐dependent above Ta = 185 °C and temperature‐ and time‐dependent below Ta = 60 °C. Two melting transitions, T and T, were observed for those samples annealed above 120 °C. No significant change in T was observed as a function of Ta while T showed strong dependency on Ta. Digital subtraction of the amorphous contribution from the semicrystalline FIR spectra provided characteristic spectra of amorphous and crystalline PTT. The bands at 373, 282, and 92 cm−1 were assigned to the crystalline phase, while the bands at 525, 406, and 351 cm−1 were attributed to the amorphous phase. It was shown that FIR spectroscopy can be used as a means to estimate the degree of crystallinity of PTT. The band ratio of 373 and 501 cm−1 was plotted against crystallinity measured by density and reasonably good correlation was obtained. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1675–1682, 2007
Structural and electrical properties of LiBa2V5O15 ceramics
Authors: Behera Banarji , Nayak P. , Choudhary R. N. P. 
Published: May 2007

AbstractA polycrystalline sample of LiBa2V5O15 (LBV) was prepared by a mixed‐oxide method at low temperature (560 °C). Preliminary structural analysis suggests that the compound has an orthorhombic unit cell and crystal structure. Scanning electron micrographs of the compound show a densely packed grain distribution over the entire surface of the sample. Detailed studies of the dielectric properties of the compound as a function of temperature at various frequencies suggest that the compound has a dielectric anomaly at 319 °C. Some electrical parameters of LBV were measured using a complex impedance spectroscopy technique in a wide range of temperature (24–500 °C). The complex impedance plots show that there are two major contributions of impedance, bulk (grains) and grain boundary, and there is a non‐Debye type of dielectric dispersion. The ac/dc conductivity was found to increase with increasing temperature. The activation energy of the compound was found to be 0.38 eV. This value of activation energy suggests that the conduction process is of mixed type (ionic–polaronic and space charge generated from the oxygen ion vacancies). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local order in ZnGeP2:Mn crystals
Authors: Bacewicz R. , Pietnoczka A. , Gehlhoff W. , Voevodin V. G. 
Published: May 2007

AbstractX‐ray absorption fine structure is investigated in ZnGeP2:Mn crystals at K‐edge of Zn, Ge and Mn. Both, the XANES and EXAFS results indicate that Mn atoms substitute on cationic sites in the chalcopyrite structure. It is, however, impossible to discriminate between MnZn and MnGe sites due to similar photo‐ electron scattering amplitudes of Zn and Ge atoms in the second coordination shell of Mn atom. The nearest‐neighbour distance Mn–P is up to 3% longer than the Zn–P bond length. The second‐ and third‐neighbour atoms were found to remain at distance close to the host lattice positions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct analysis of isopropylthioxanthone (ITX) in milk by high‐performance liquid chromatography/tandem mass spectrometry
Authors: Bagnati Renzo , Bianchi Giancarlo , Marangon Elena , Zuccato Ettore , Fanelli Roberto , Davoli Enrico 
Published: May 2007

AbstractA fast screening method is presented for detecting isopropylthioxanthone (ITX) contamination in milk. The method is based on direct high‐performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) analysis of milk samples. Sample preparation is limited to the addition of a deuterated ITX solution in acetonitrile that serves both as internal standard and to precipitate proteins. The method is highly accurate and sensitive. Isomeric specific analyses of 2‐ITX and 4‐ITX are possible at 6 µg/L levels with about 5% precision and accuracy. This approach has been used to check contamination in samples like milk, soy milk, baby milk, in their packaging material. Out of 37 milk samples analyzed, 16 were positive with concentrations ranging from 173–439 µg/L for 2‐ITX and from <6 (lower than limit of quantification) to 25 µg/L for 4‐ITX. Copyright © 2007 John Wiley & Sons, Ltd.
Stable robust feedback control system design for unstable plants with input constraints using robust right coprime factorization
Authors: Deng Mingcong , Inoue Akira , Yanou Akira 
Published: May 2007

AbstractA stable robust control system design problem for unstable plants with input constraints is considered using robust right coprime factorization of nonlinear operator. For obtaining strong stability of the closed‐loop system of unstable plants with input constraints, a design scheme of robust nonhyphen‐linear control system is given based on robust right coprime factorization. Some conditions for the robustness and system output tracking of the unstable plant with input constraints are derived. Numerical examples are given to demonstrate the validity of the theoretical results. Copyright © 2007 John Wiley & Sons, Ltd.
On complete Lyapunov–Krasovskii functional techniques for uncertain systems with fast‐varying delays
Authors: Fridman Emilia , Niculescu Silviu‐Iulian 
Published: May 2007

AbstractStability of linear systems with norm‐bounded uncertainties and uncertain time‐varying delays is considered. The delay is supposed to be bounded and fast varying (without any constraints on the delay derivative).Sufficientstability conditions are derived by direct Lyapunov method based on thecomplete Lyapunov–Krasovskii functional(LKF). A novel complete LKF construction is presented: the derivative condition for the nominal LKF (i.e. for the LKF, which corresponds to the system with the nominal values of the coefficients and of the delay) depends on the ‘present’ state only. The comprehensive technique for stability analysis of uncertain time‐delay systems is extended to the case of complete LKF: the application of free weighting matrices (instead of descriptor model transformation) and of Jensen's inequality (instead of the cross‐terms bounding). Numerical examples illustrate the efficiency of the method, and complete the paper. Copyright © 2007 John Wiley & Sons, Ltd.
From music into silence: an exploration of music‐thanatology vigils at end of life
Authors: Cox Helen , Roberts Peter 
Published: May 2007

AbstractRecently Helen Cox recorded a conversation with music‐thanatologist, Peter Roberts (Spirituality & Health International, 2006, Vol. 7, No. 1). This paper describes aspects of the findings from a multi‐method study into the effects of this work on six patients who were inpatients at St John of God Hospital in Geelong. A total of 21 live harp vigils were observed over a period of nine months. A researcher observed and recorded details of each vigil, interviewed patients, relatives, nurses and pastoral care staff, and recorded personal observations. The music‐thanatologist audiotaped reflections after each vigil. This paper describes findings from the perspective of patients. A key finding of this research is that music‐thanatology makes a profound difference to the way that people experience the end‐of‐life journey. The prescriptive live harp music vigils take people beyond the music into a silence that is deeply spiritual and profoundly comforting. Copyright © 2007 John Wiley & Sons, Ltd.
Bilateral avulsion of the puborectal muscle: magnetic resonance imaging‐based three‐dimensional reconstruction and comparison with a model of a healthy nulliparous woman
Authors: Otcenasek M. , Krofta L. , Baca V. , Grill R. , Kucera E. , Herman H. , Vasicka I. , Drahonovsky J. , Feyereisl J. 
Published: May 2007

AbstractObjectivesObstetric trauma to the puborectal muscle seems to be an important cause of pelvic floor dysfunction in women. Due to the complicated three‐dimensional (3D) arrangement of the pelvic structures, two‐dimensional images are not sufficient to demonstrate its relationships in a complex fashion. Thus, we aimed to create a 3D computer model to visualize the normal female pelvic floor anatomy and to compare this with the anatomy after bilateral avulsion of the puborectal muscle following delivery.MethodsWe created two 3D computer models of the female pelvic floor, one of a healthy nulliparous woman and the other of a woman with bilateral puborectal muscle avulsion after vaginal delivery. The data for the models were obtained from magnetic resonance imaging examinations and the following structures were depicted: pelvic bones, puborectal muscle, internal obturator muscle, urethra, urinary bladder, vagina and rectum. The models were compared.ResultsThe models allowed us to demonstrate in three dimensions changes in the puborectal muscle after avulsion. Its relations to the bone, internal obturator muscle, perineal membrane and the deep part of the external anal sphincter were modeled and differences from the normal non‐injured anatomy were demonstrated. Avulsion altered the support to the whole endopelvic fascia and destabilized both the anterior and the posterior vaginal walls.ConclusionsThe use of 3D technology including modeling allows for the acquisition of new knowledge and aids in the understanding of both normal and pathological pelvic anatomy. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
On the Theory of Thin Airfoils in Nonequilibrium Ideal Fluids
Authors: Dragoş L. 
Published: May 2007

AbstractIn this paper the solution of thin airfoils problem in nonequilibrium ideal fluids is given. No use of the distribution theory as in Homentcovschi solution [1] is done. In the frozen subsonic case the boundary value problem is reduced to the integral equation (12) which is asymptotically integrated for τ ≫ 1. In the frozen supersonic case the boundary value problem is reduced to the integral equation (25) which is solved exactly. The solution for the motion in the presence of an infinite wall is given too.
Zur Regularität von Finite Element‐Transformationen zweiter Ordnung
Authors: Gründemann H. 
Published: May 2007

AbstractRegularitätsbedingungen für Finite Element‐Transformationen vierseitiger 8‐Knoten‐Elemente werden aus Abschätzungen der Funktionaldeterminante hergeleitet. Darüber hinaus sind diese Abschätzungen für Konvergenz‐ und Approximations‐untersuchungen nützlich. Neben analytischen Formeln, die direkt in EDV‐Programmen auswertbar sind, stehen geometrische Deutungen zur Elementregularität im Mittelpunkt.
Numerical Maximization of Derivatives by Successive Polynomial Interpolation
Authors: Van Griend J. A. De 
Published: May 2007

AbstractA general class of numerical methods for maximizing derivatives of a real function in one variable is presented. These methods (the so‐called SPI methods) are based on successive polynomial interpolation. Our class includes known methods of Tamir and of Brent. In this paper we derive the order of convergence of the general SPI‐methods, thus generalizing related convergence results for some special methods obtained before by Brent, Burmeister, Schmidt and Tamir.
Fundamental Solutions of the Linear Elastostatics Equations of the Isotropic and Homogeneous Bodies with Microstructure Having a Symmetric Stress Tensor
Authors: Crâciun I. , Crâciun A. 
Published: May 2007

AbstractIn this paper the linear theory of the elastostatics of the homogeneous and isotropic bodies with microstructure having a symmetric stress tensor is considered. The matrix of fundamental solutions ℐ(x, y) of the operator A(∂/∂x) governing this theory is deduced. The stress operator ℐ(∂/∂x, n(x)) is introduced and the expression of the matrix ℐ(∂/∂x, n(x)) Γ(x, y) is given. Finally, some properties of the matrix λ(x, y) = t(ℐ(∂/∂y, n(y)) ℐ(y, x) are given.
Boundary Integral Formulation of Crack Problems
Authors: Sládek V. , Sládek J. , Balaš J. 
Published: May 2007

AbstractIn this paper the non‐perturbative theory of crack dislocations is developed on the basis of an advanced boundary integral formulation of crack problems. The distribution of crack dislocations is determined by the boundary integro‐differential equations derived from the regularized integral representation of the stress field. The method is applicable to the cracked body with any crack profile and the topics discussed include the formulation of cracks problems in: (i) elastostatics; (ii) elastodynamics; and (iii) thermoelasticity.
A Comparative Survey of Numerical Methods for the Linear Generalized Abel Integral Equation
Authors: Te Riele H. J. J. , Schroevers Ph. 
Published: May 2007

AbstractA numerical comparison is made between a number of important representatives of the following classes of methods: (i) collocation, (ii) product integration and (iii) global methods. Special attention is paid to the performance of these methods for problems with a non‐smooth solution. It turned out that, when only relatively low accuracy is required, a good choice would be a second or third order collocation method of Branca. — A new collocation method which accounts for possible non‐smoothness of the solution near the origin, turned out to be advantageous when high accuracy is required, both for problems with a non‐smooth solution, and for problems with a smooth solution.
Description of Initial and Subsequent Yield Surfaces
Authors: Gupta N. K. , Meyers A. 
Published: May 2007

AbstractA function of second and third invariants of the translated deviator stress tensor is proposed for the description of experimentally observed deviations from the von Mises ellipse in the initial yield surface, as well as from translation, rotation or change in size and shape of a subsequent yield surface. Application of the proposed relation is demonstrated by comparing it with some experimental data taken from the literature.
Erweiterung der Bewegungsgleichungen von Mehrkörpersystemen zur Berücksichtigung von Reibung und Regelung
Authors: Schwertassek R. , Türk S. 
Published: May 2007

AbstractMehrkörpersysteme sind die zur Untersuchung vieler Fragestellungen aus Raumfahrt, Maschinendynamik, Fahrzeugtechnik, und Robotik geeigneten mechanischen Ersatzmodelle. Die Erstellung der Bewegungsgleichungen solcher Systeme ist arbeitsintensiv und wird heute meistens durch Rechner unterstützt. Ein rechnerorientiertes Verfahren zur Ermittlung der Bewegungsgleichungen wird hier mit dem zugehörigen Programm vorgestellt. Erweiterungen zur Behandlung von Systemen mit Reibung und Regelung werden angegeben, und die Arbeitsweise des Programms wird an einem einfachen Beispiel demonstriert.
Effect of Prestress on Pulse Waves in Arteries
Authors: Demiray H. , Erbay H. A. , Erbay S. 
Published: May 2007

AbstractIn order to understand the effect of initial stresses on the blood flow in arteries, a theoretical analysis of wave propagation in an initially inflated and axially stretched thick cylindrical shell filled with a viscous fluid is investigated. For simplicity in mathematical analysis, the blood is assumed to be an incompressible Newtonian fluid while the arterial wall material is taken to be incompressible, homogeneous, isotropic and elastic. Utilizing the theory of small deformations superimposed on a large initial deformation, the governing differential equations of the perturbed solid motions are obtained in cylindrical polar coordinates. Because of the difficulties in solving the set of differential equations with variable coefficients, an approximate power series method is utilized and the dispersion relation is obtained for thin tubes. Various results concerning the wave speeds and transmission coefficients are numerically evaluated and the results are depicted on some graphics.
Dynamics of Linear Elastic Structures with Selfstress: A Unified Treatment for Linear and Nonlinear Problems
Authors: Irschik H. , Ziegler F. 
Published: May 2007

AbstractA semi‐numerical method for the solution of dynamic problems of linear and nonlinear structures is presented under the unifying aspect of sources of self‐stresses. Conceptually applications are possible to the Finite Element and the Boundary Element Method in time as well as in the frequency domain. In addition to physical nonlinearities of viscoplasticity also geometrically nonlinear problems are considered. Effects of refined linear theories are discussed.
Transient Wave Motions Due to an Asymmetric Shear Stress Discontinuity in a Layered Elastic Medium
Authors: Maiti N. C. , Debnath L. 
Published: May 2007

AbstractA study is made of the generation and propagation of transient wave motions in a layered elastic medium due to an asymmetric discontinuity of shear stress acting over a finite circular region at the interface of the composite medium. The problem is solved by the joint Laplace and Hankel transforms combined with Cagniard's method for exact evaluation of the integral solution. Surface P‐ and SV‐ wave motions are obtained in closed form assuming both dilatational and shear wave velocities are equal in the top finite layer and in the half space. On the other hand, SH‐wave motion for the general case is expressed in a series, each term of which is evaluated exactly by Cagniard's method. It is shown that the solution is oscillatory in nature and the number of oscillations increases with increasing asymmetry and decreasing ratio of the thickness of the upper layer to the radius of the circular region of the applied stress distribution. Some numerical calculation is carried out to investigate the nature of the displacement field as well as the reflected pulses. Numerical results are graphically presented in three diagrams.
Multiaxial Anisotropic Creep Behaviour of Rolled Sheet‐Metals
Authors: Betten J. , Brettbach G. , Waniewski M. 
Published: May 2007

AbstractMultiaxial creep behaviour is analysed within an invariant formulation of the secondary creep constitutive equations for orthotropic solids, developed in the framework of the theory of tensor function representations. The biaxial tension method is improved in order to determine complex stress state in specimen of orthotropic rolled sheet‐metal. The shape of the specimen is taken into account with respect to the uniform stress state by applying the finite element codes.
On the Elastic‐plastic Shrink Fit with Supercritical Interference
Authors: Gamer U. , Müftü S. 
Published: May 2007

AbstractShrink fits with perfectly elastic‐plastic hub material cannot be treated with the help of Tresca's yield criterion, if the ratio of outer and inner diameter as well as the interference exceed certain limits. For linear hardening material, however, a solution exists for all radii ratios. It is shown that, for small hardening, the material in the neighbourhood of the interface undergoes a twofold change of the yield condition.
Shape Variations for Viscoelastic Solids Under Transient Response
Authors: Meric R. A. 
Published: May 2007

AbstractSensitivity expressions for a general performance criterion (cf. an integral functional) with respect to shape have been derived for viscoelastic solids under transient response. Differential and integral types of constitutive equations are considered in the study, in which a continuum approach is adopted. By using the material derivative concept and the adjoint variable method the sensitivity of the general integral functional is obtained in terms of primary and adjoint functions. A simple example problem is also provided to check the results by comparing them with those found by a direct differentiation.
Porous Rayleigh Step Bearing with Second‐Order Fluid
Authors: Bujurke N. M. , Naduvinamani N. B. , Jagadeeswar M. 
Published: May 2007

AbstractThe theoretical analysis of a porous Rayleigh Step bearing lubricated by a second‐order fluid is considered. An approximate method for the solution of the governing fluid film equations and Darcy's equations for a porous region is proposed. Compact expressions for the pressure distribution, load capacity and the frictional coefficient are obtained. Calculations of the dimensionless load capacity, frictional force and frictional coefficients are presented for specific values of the material parameters. It is found that the load carrying capacity decreases and the frictional force and frictional coefficients increase compared to that of the solid case. The maximum dimensionless load capacity is found to occur at a slightly smaller step ratio as compared to the solid case. It is of quite interest to note that the limiting forms of the expressions obtained approach the exact forms of the results of the Newtonian case quoted in detail in Hughes [15].
Singularities of Rotationally Symmetric Solutions of Boundary Value Problems for the Lamé Equations
Authors: Beagles A. E. , Sändig A.‐M. 
Published: May 2007

AbstractWe apply the theory of elliptic boundary value problems in non‐smooth domains with conical points to rotationally symmetric solutions of boundary value problems for the Lamé equations. The resulting expansion involves singular vector‐functions which, in turn, depend on a parameter, α. We here present equations which determine the values of α for either stress‐free or Dirichlet boundary conditions. We give a numerical algorithm whereby α can be computed and present some plots of the values obtained. The singular vector‐functions are given explicitly and we present equations for the computation of the coefficients of the expansion.
Shear Waves in Nonhomogeneous Multi‐Storeyed Buildings
Authors: Mioduchowski A. 
Published: May 2007

AbstractIn the paper the continuous model of a nonhomogeneous multi‐storeyed building is considered. The method of dynamical analysis is based on the theory of propagation of one dimensional shear elastic waves. Detailed discussion is presented for a nonhomogeneous three storey building, and final equations for a nonhomogeneous N storey building are given. Some numerical results are presented graphically for a three storey building.
Das Driftmodell für Fließgewässer mit Schwebstoffen
Authors: Förste J. 
Published: May 2007

AbstractAusgehend vom Driftmodell für Zweiphasenströmungen wird für fließende Oberflächengewässer mit stofflichen Beimengungen ein Rand‐Anfangswertproblem formuliert. Für dieses läßt sich die eindeutige Lösbarkeit nachweisen. Dabei konvergiert das Galerkinverfahren für zwei‐ und dreidimensionale Strömungen unter unterschiedlichen Bedingungen. Für zweidimensionale Strömungen kann die Existenz eines Attraktors nachgewiesen werden, seine Hausdorffsche Dimension läßt sich durch gegebene Ausgangsgrößen abschätzen.
Variational Formulation of the Crack Problem for an Elastoplastic Body at Finite Strain
Authors: Stumpf H. , Le K. C. 
Published: May 2007

AbstractWithin the framework for finite strain elastoplasticity a new formulation of the boundary value problem for an elastoplastic cracked body by a variational inequality is proposed. A well‐posed system of governing equations and boundary conditions derived from this variational inequality enables us to determine the location as well as the preferred direction of propagation of the crack. It is shown that the variational inequality of evolution along with the non‐holonomical constraints can be used to formulate the dynamic problem for a thermoplastic cracked body.
Resonance in a Rigid Rotor with Elastic Support
Authors: Ruijgrok M. , Tondl A. , Verhulst F. 
Published: May 2007

AbstractA model is formulated for a rotor with elastic support in axial and lateral directions which leads to the problem of stability of small vertical oscillations in the upright position. This is an autoparametric excitation problem which can be formulated as two coupled Mathieu‐like equations. The analysis of the cases without and with (linear) damping and the case of nonlinear damping is carried out using averaging and numerical bifurcation techniques leading in the nonlinear case to hysteresis and phase‐locking.