bluuebunny/crossref_metadata_2025_split huggingface dataset:
GPRS system enhancement by employing LDPC codes
Authors: Keyrouz Fakheredine , Xu Wen 
Published: May 2007

AbstractWe address the application and design of low‐density parity‐check (LDPC) codes to enhance the General Packet Radio Service (GPRS) system in order to support services such as the Multimedia Broadcast Multicast Service (MBMS). Advances in coding theory and further reduction in integrated circuit size have promoted LDPC codes to become one of the most attractive forward error correction (FEC) technologies in practice. The GPRS as well as enhanced GPRS (EGPRS) system currently uses the well‐known convolutional code (CC) as an FEC mechanism, and the Viterbi algorithm for decoding. With the recent introduction of MBMS, new applications that require more bandwidth and reliability are foreseen. It is known that the current (E)GPRS system does not perform well enough without further modifications, therefore, more efficient information distribution schemes need to be considered. To meet these increased requirements, especially for MBMS, we study the introduction of carefully designed LDPC codes at the physical layer. To exploit the full benefit of the superior performance of LDPC codes for large data block lengths, a modification in the GPRS protocol stack is proposed where larger RLC/MAC blocks are allowed, and its impact on the existing GPRS protocol stack is minimised. Copyright © 2007 John Wiley & Sons, Ltd.
Discordant lymphatic drainage patterns revealed by serial lymphoscintigraphy in cutaneous head and neck malignancies
Authors: Willis Alliric I. , Ridge John A. 
Published: May 2007

AbstractBackground.We analyzed the variability and accuracy of sentinel lymph node (SLN) identification by lymphoscintigraphy performed preoperatively and repeated on the day of operation in patients with melanoma or Merkel cell cancer.Methods.Twenty‐five prospectively studied patients had lymphoscintigraphy prior to and on the day of operation. Discordance between lymphoscintograms was defined as change in location of SLN or failure to identify a SLN by one of the studies.Results.In 22 of 24 assessable cases (92%), SLNs were excised. Preoperative lymphoscintigraphy was correct in 19 of 22 (86%) cases. Day of operation lymphoscintigraphy was correct in 20 of 22 (91%) cases. SLN location was as classically described in 24 of 25 (96%) cases. Discordance between lymphoscintigraphy studies was 32% (8/25 patients). Half with discordant migration (8%) yielded metastases in basins not identified by day of operation lymphoscintigraphy but demonstrated by preoperative lymphoscintigraphy.Conclusions.Head and neck lymphatic drainage patterns not only vary between patients but also can vary with time for a single patient. © 2007 Wiley Periodicals, Inc. Head Neck 2007
First and second line imatinib treatment in chronic myelogenous leukemia patients expressing rare e1a2 or e19a2 BCR–ABL transcripts
Authors: Andrikovics Hajnalka , Nahajevszky Sarolta , Szilvási Anikó , Bors András , Ádám Emma , Kozma András , Kajtár Béla , Barta Anikó , Poros Anna , Tordai Attila 
Published: May 2007

AbstractDuring the formation of the Philadelphia (Ph) chromosome, in the majority of chronic myelogenous leukemia (CML) patients, the chromosome 22 breakpoint is located in the major breakpoint cluster region of the BCR gene (M‐bcr). Minor and micro breakpoint cluster regions (m‐bcr with e1a2 transcript and µ‐bcr with e19a2 transcript) are rarely affected and have been suggested to be associated with peculiar CML phenotypes. Despite the different clinical characteristics, it is currently not established, whether different therapeutic options are preferably recommended for the treatment of e1a2 or e19a2 CML. Here we report two patients with e1a2 and one patient with e19a2 translocations, treated with different approaches including imatinib. First and second line imatinib treatments induced haematologic response in all of the three patients, and major cytogenetic response in one patient with e1a2, as well as in the patient with e19a2 CML. However, relapse occurred in the patient with e19a2 CML, possibly caused by the presence of additional chromosomal abnormalities such as an extra Ph chromosome, and loss of chromosome Y. Stem cell transplantation (SCT) therapy caused complete haematologic response with molecular remission; however, the patient died of infectious complication. We conclude that in patients with rare BCR–ABL variants, the effectiveness of imatininb treatment may be influenced by the CML stage besides the actual molecular type of the rare transcript. However, this conclusion cannot be generalized to larger patient groups with rare BCR–ABL variants for which further studies may be needed. Copyright © 2007 John Wiley & Sons, Ltd.
Reduced basis approximation and a posteriori error estimation for stress intensity factors
Authors: Huynh D. B. P. , Patera A. T. 
Published: May 2007

AbstractWe develop reduced basis approximations, rigorous a posteriori error bounds, and offline–online computational procedures for the accurate, fast, and reliable prediction of stress intensity factors or strain energy release rates for ‘Mode I’ linear elastic crack problems relevant to fracture mechanics. We demonstrate the efficiency and rigor of our numerical method in several examples. Copyright © 2007 John Wiley & Sons, Ltd.
Gas solubility and permeability in MFA
Authors: Fossati P. , Sanguineti A. , De Angelis M. G. , Baschetti M. G. , Doghieri F. , Sarti G. C. 
Published: May 2007

AbstractAn experimental analysis has been performed in this work, aimed to the characterization of thermodynamic and mass transport properties of a semicrystalline fluoro polymer (MFA) obtained from the copolymerization of tetrafluoroethylene (TFE) and perfluoromethylvinylether. Sorption and permeation experiments for two alkanes and corresponding perfluorinated compounds in MFA were performed at two different temperatures and solubility coefficients, as well as diffusivity and permeability, were determined. Experimental data were analyzed through different thermodynamic models to draw general conclusions about properties of MFA polymeric phases. Special attention was devoted to the glassy nature of MFA polymeric mixtures around room temperature. Indeed, analysis of experimental sorption data was performed through the use of specific models for glassy polymeric phases as well as by means of classical equilibrium models for fluid mixtures. Conclusions have been drawn from the aforementioned analysis, which significantly contributes to the discussion of correct location of glass‐transition temperature for PTFE and its copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1637–1652, 2007
Advantages of thin single‐photon avalanche diodes
Authors: Tan S. L. , Ong D. S. , Yow H. K. 
Published: May 2007

AbstractThe breakdown characteristics and timing jitter of thin and thick GaAs single‐photon avalanche diodes are analyzed using a random ionization path length model. The larger relative dead space in thin devices is found to increase the sharpness of breakdown probability curves. Thin devices also produce lower timing jitter as a result of larger feedback ionization at high fields and weak dependence of jitter on dead space. Thus, if the dark count rate associated with higher electric field can be compensated, then thin devices may offer better performance in terms of faster breakdown and lower timing jitter, in addition to the known benefits of shorter detector dead time and velocity overshoot effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Amorphous BeN as a new solid host for rare‐earth‐related luminescent materials
Authors: Zanatta A. R. , Richardson H. H. , Kordesch M. E. 
Published: May 2007

AbstractBeryllium‐nitride (BeN) thin films were prepared by sputtering a Be target in an atmosphere of pure nitrogen. The films were doped with samarium simply by placing a piece of Sm metal on the surface of the Be target. Under these deposition conditions the films present an amorphous structure and an optical bandgap of approx. 4 eV. They also exhibit visible light emission due to Sm3+ ions as a result of either photon or electron excitation. The present experimental results show that amorphous BeN films are suitable, and efficient, III‐nitride hosts for rare‐earth doping purposes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Osculatory Extension of Cauchy's Rational Interpolation Formula
Authors: Salzer H. E. 
Published: May 2007

AbstractAn explicit formula for osculatory rational interpolation, in terms of functional values at every node, and any number of consecutive derivatives at one node, is derived from Cauchy's rational interpolation formula by solving the equivalent problem of finding the corresponding confluent limits of a non‐linear generalization of divided differences.
Stabilitätsuntersuchungen mit Hilfe der kontinuierlichen Thermodynamik
Authors: Bergmann J. , Kehlen H. , Rätzsch M. T. 
Published: May 2007

AbstractDie kontinuierliche Thermodynamik [1–5] stellt eine Version der Thermodynamik dar, bei der die Zusammensetzung durch eine kontinuierliche Verteilungsfunktion statt durch die Molenbrüche individueller Komponenten beschrieben wird. Dadurch ermöglicht sie eine einfache Behandlung komplexer Vielstoffgemische, in denen eine große Zahl sehr ähnlicher Molekülarten auftritt (Erdöl, Polymere). Die übliche Form der thermodynamischen Stabilitätstheorie mit den bekannten Determinantenkriterien ist im Rahmen der kontinuierlichen Thermodynamik nicht anwendbar. In der vorliegenden Arbeit wird die Stabilitätstheorie auf eine Form gebracht, die der Beschreibung der Zusammensetzung durch Verteilungsfunktionen angepaßt ist.
Onset of Chaos and Global Analytical Solutions for Duffing's Oscillator
Authors: Schmidt G. 
Published: May 2007

AbstractFor the example of Duffing's oscillator, the discrepancy between the onset of chaotic motions found numerically and the results of analytical approximation is investigated by an analytical‐numerical method of trigonometric iteration. A fanning of the approximate response curves is found which corresponds to the non‐convergence of the approximations and the onset of chaotic motions.
General Concept of the Analysis of Thin Elastic Shells
Authors: Stumpf H. 
Published: May 2007

AbstractUnder the assumption of small strains the Lagrangian equations of the unrestricted rotation shell theory can be derived by applying the stationarity principle of total potential energy. It is shown that for a non‐rational change of the curvature tensor the equilibrium equations, the static boundary conditions and also the geometric boundary conditions are non‐rational partial differential equations. A nonlinear operator description is introduced allowing to formulate in a compact form the unrestricted rotation shell theory as well as the energy‐consistent simplified theories including the linear shell theory and various types of moderate and large rotation shell theories. The equations of an incremental deformation analysis, the stability and the postbuckling equations are derived and it is shown that they can be represented as functions of the Gâteaux differentials of the introduced shell operators. As an example of a highly nonlinear shell structure a torus under ring‐load is calculated numerically by applying the shallow shell theory, a moderate and a large rotation shell theory.
Ein vierdimensionales Abbildungsprinzip für ebene Bewegungen
Authors: Wunderlich W. 
Published: May 2007

AbstractDie Punktbahnen eines ebenen Zwanglaufs π'/π werden gedeutet als verschiedene Parallelprojektionen einer gewissen Bild kurve k in einem vierdimensionalen euklidischen Raum R4, der die Rastebene π enthält. Die Projektionsachsen bilden ein elliptisches Strahlnetz im Fernraum des R4 und sind den einzelnen Punkten der Gangebene π' zugeordnet, während die Punkte von k den einzelnen Lagen von π' entsprechen. Das Abbildungsprinzip erweist sich insbesonders für algebraische Zwangläufe als nützlich und wird durch Beispiele illustriert. Auch die beiden Polkurven der Bewegung sind vom R4 aus deutbar.
Laminated Orthotropic Plates under Subdifferential Boundary Conditions. A Variational‐Hemivariational Inequality Approach
Authors: Stavroulakis G. E. , Panagiotopoulos P. D. 
Published: May 2007

AbstractThis paper deals with an orthotropic laminated plate concerning the delamination problem. A nonmonotone multivalued law simulates the mechanical behaviour of the binding material. This law is written in terms of a generalized gradient (in the sense of F. H. Clarke) of an appropriately defined nonconvex superpotential. Moreover, monotone, e.g. frictional slipallowing boundary conditions of subdifferential type are assumed to hold, which are obtained from a convex superpotential through subdifferentiation. The problem is formulated as a variational‐hemivariational inequality which physically expresses the principle of virtual work in inequality form. The existence and the approximation of the solution of this inequality is discussed by an appropriate combination of compactness, monotonicity and average value arguments.
Three Routes to Chaos in Simple Sinusoidally Driven Oscillators
Authors: Awrejcewicz Jan 
Published: May 2007

AbstractEs werden drei verschiedene Szenarien für sehr einfache nichtlineare Schwinger unter sinoidaler Anregung aufgezeigt, die von periodischer zu chaotischer Bewegung führen. Die numerische Vorgehensweise basiert auf dem Schieß‐Verfahren. Periodische Orbits werden bei Parameteränderung anhand der Charakteristischen Multiplikatoren verfolgt. Es werden Übergänge diskutiert, bei denen einer der Multiplikatoren den Einheitskreis bei + 1 oder —1 (Periodenverdopplung) kreuzt. Das dritte Beispiel zeigt Chaos, nachdem ein Multiplikatoren‐Paar gleichzeitig den Einheitskreis überquert.
The Convergence of Discretization Methods if Applied to Weakly Formulated Problems. Theory and Examples
Authors: Ansorge R , Lei J 
Published: May 2007

AbstractThe general theory of the convergence of discretization algorithms founded by STUMMEL and GRIGORIEFF and later extended to nonlinear problems by numerous authors does not completely fit the numerical treatment of linear or nonlinear weakly formulated problems. Such an extension is presented together with examples of nonlinear elliptic and hyperbolic PDEs. Often the transition from classical to weak solutions leads to a loss of uniqueness such that uniqueness can only be guaranteed by additional conditions, e. g. suitable inequality constraints. How such constraints must generally be discretized in order to make the numerical solution converge to the corresponding unique weak solution is also discussed, and the results are particularly compared with entropy conditions of conservation laws. The examples are only treated in order to motivate the general theory and to demonstrate its applicability.
Unsteady Stokes Flow in a Distensible Pipe
Authors: Luchini P. , Lupo M. , Pozzi A. 
Published: May 2007

AbstractIn this paper the solution is presented of the problem of unsteady Stokes flow in a semi‐infinite distensible pipe, with initial conditions given at the pipe inlet. The solution is obtained through an eigenfunction expansion, utilizing Van Kampen's method for the determination of the expansion coefficients. In this way a complete description is obtained of the velocity and pressure profiles throughout the pipe.
Spatially Amplifying Waves in Plane Poiseuille Flow
Authors: Brevdo L. 
Published: May 2007

AbstractThe initial‐boundary‐value linear stability problem for two‐dimensional plane Poiseuille flow is treated by means of Fourier‐Laplace transform. Spatially amplifying waves in this flow are studied numerically for a wide range of Reynolds numbers R. It is shown that transition to turbulence may be accompanied by a selection of low frequencies in spatially amplifying nonstationary waves with small spatial undulations. No stationary spatially amplifying waves exist in this flow.
Monotonieerhaltende upwind‐Schemata im zweidimensionalen Fall
Authors: Kratsch F. , Roos H.‐G. 
Published: May 2007

AbstractStandarddiskretisierungsverfahren sind zur Behandlung von konvektionsdominanten Problemen nicht geeignet, da insbesondere die Existenz von Grenzschichten zu Instabilitäten des diskreten Problems führt. Wir suchen nach einem einfachen, gleichmäßig stabilen Diskretisierungsverfahren der Ordnung 2 im zweidimensionalen Fall, für das im globalen Gebiet keine Ordnungsreduktion eintritt, wenn der Störungsparameter gegen Null geht. Es zeigt sich, daß es kaum möglich ist, bewährte Schemata vom eindimensionalen auf den zweidimensionalen Fall zu übertragen. Für eine spezielle upwind‐Technik jedoch kann die Inversmonotonie des diskreten Problems bewiesen werden.
Convergence of Discretizations of Nonlinear Problems. A General Approach
Authors: Ansorge R. 
Published: May 2007

AbstractIn 1948 Kantorovich published his famous paper on connections between Numerical Mathematics and Functional Analysis. Particularly for Numerical Analysis, the paper [31] of Lax and Richtmyer (1956) on the numerical treatment of (linear) partial initial value problems made Functional Analysis an instrument definitively adopted by numerical analysts.A more general theory for the description and investigation of discretization methods – influenced by the Lax‐Richtmyer Theory and its extensions but not restricted to PDEs – was aroused by papers of Stummel in the 70s. A well developped Functional Analysis of Discretization Algorithms (Vainikko) came into being.After a brief historical summary, some modern aspects of the theory will be discussed, e.g. a general access to the problem of convergence of approximate solutions to weak and not necessarily unique solutions of operator equations, discretization of entropy conditions, extension of the theory to problems where convergence of the numerical solutions to weak solutions can not be guaranteed in the sense of a norm topology but only in the sense of weak convergence or weak set convergence etc.Concrete examples demonstrate the applicability of the theory.
Management and Control of Turbulent Shear Flows
Authors: Fernholz H. H. 
Published: May 2007

AbstractThis survey will begin with a few historical aspects, describe some passive and active management methods, and discuss selected examples of manipulation of leading edge separation. It will then deal with some typical flow phenomena which are important for the manipulation of turbulent shear flows. A display of active means to manipulate open separation will be followed by a practical example of forcing a separated boundary layer to reattach and to form a closed reverse‐flow region. The survey will end with a few remarks on control.
Bifurcation of the Cubic Map Related to Numerical Errors of a First‐Order Differential Equation
Authors: Klepp H. J. 
Published: May 2007

AbstractIt is shown that the one‐ and two‐dimensional cubic maps can be considered as formulae for the determination of approximations for the solution v = v(t) of the differential equation dv/dt = ‐v(v2 ‐ 1) established with the polygon and mixed polygon method. Periodical and irregular behaviour of the iterates vk of these formulae occur because of the weak stability of these methods, due to too large integration steps, and as a result of starting errors. These properties of the iterates vk are properties of the numerical errors ϵk = v(tk) − vk, too.
Analysis of Small Vibrations of Coupled Fluid‐Structure Systems
Authors: Wandinger J. 
Published: May 2007

AbstractThe article deals with the non‐selfadjoint eigenvalue problem arising in the analysis of linear vibrations of coupled fluid‐structure systems when the fluid is described by its pressure filed. First the completeness of the eigenvectors is verified. Then a simple relationship between the eigenvectors of the original problem and those of the adjoint problem is derived. To solve the eigenvalue problem a subspace iteration procedure is presented. The results are also extended to systems with rigid body motions and constant pressure fields.
A General Solution Technique for Piezothermoelasticity of Hexagonal Solids of Class 6mm in Cartesian Coordinates
Authors: Ashida F. , Tauchert Th. R. , Noda N. 
Published: May 2007

AbstractPiezoelastic materials have attracted considerable recent attention because of their potential use in “intelligent” structural systems. In this paper, we propose a general solution technique for three‐dimensional problems of piezothermoelasticity for hexagonal solids of class 6mm in cartesian coordinates. Potential functions are introduced to represent the coupled elastic and electric fields. Simple uncoupled governing equations for the potential functions are derived from he stress equations of is analyzed. Numerical calculations for the stresses and the electric potential are carried out for a cadmium selenide body exhibiting class 6mm symmetry. Stress distributions are compared with those obtained for the similar thermoelastic problem without the piezo‐effect.
Analytical Solutions and a Numerical Algorithm for the Gauss's Hypergeometric Function 2F1 (a, b; c; z)
Authors: Mayrhofer K. , Fischer F. D. 
Published: May 2007

AbstractThe paper deals with the derivation of the analytical solution of a definite elliptical integral of general type which appears in fracture mechanics. The closed‐form solution is expressible in terms of the Gauss hypergeometric series 2F1 (a, b; c; z). As an alternative, the authors further present a suitable set of recurrence formulas and the accompanying starting solutions. Their application leads to other closed‐form expressions for the elliptical integral which are offered in the Appendix. Therefore, as a new result, analytical expressions are given for the Gauss hypergeometric series 2F1 (a, b; c; z) for specific parameters a, b, c. A powerful algorithm for the numerical computation of 2F1 has been developed.
A Preconditioning of the Tau Operator for Ordinary Differential Equations
Authors: Cabos Ch. 
Published: May 2007

AbstractFür den Operator, der bei der Chebyshevschen Tau‐Methode för lineare gewöhnliche Differentialgleichungen auftritt, wird mittels eines Integral‐Operators eine Faktorisierung angegeben. Der erste Faktor dieser Faktorisierung hat eine beschränkte Konditions‐Zahl und ist schwach besetzt, falls die Koeffizienten in der Differentialgleichung Polynome niedriger Ordnung sind. Der zweite Faktor der Faktorisierung kann leicht direkt invertiert werden. Somit wird die iterative wie auch in vielen Fällen die direkte Lösung der Tau‐Gleichung für Differentialgleichungs‐Systeme vereinfacht. Darüber hinaus kann unter Verwendung dieser Faktorisierung ein Existenz‐ und Konvergenzbeweis für die Tau‐Approximation gegeben werden. Ein ähnlicher Präkonditionierer kann für Kollokationsgleichungen definiert werden. Numerische Beispiele, bei denen iterative Löser angewendet werden, zeigen verbesserte Konvergenz sowohl für die Tau‐Methode als auch für die Kollokationsmethode.
Subharmonic Vibrations and Onset of Chaos in Driven Asymmetric Oscillators
Authors: Schmidt G. , Seisl M. 
Published: May 2007

AbstractAsymmetrische Oszillatoren treten in Mechanik, Physik und Technik auf, Beispiele sind asymmetrische Schwingungen von Schalen, gekrümmten Stäben, Pendelsystemen, Josephson‐Kontakten, SQUIDs und hängenden Kabeln. –‐ Es wird gezeigt, daß subharmonische asymmetrische Schwingungen und das Einsetzen von Chaos auf dieselbe Weise wie symmetrische Schwingungen untersucht werden könen, allerdings entstehen stets Komponenten mit geraden Harmonischen und konstante Komponenten von Anfang an, so daß die Analyse viel komplizierter ist. Beispiele unterstreichen den großen Einfluß der Asymmetrie.