bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur Konvergenz von Finite‐Elemente‐Näherungen elliptischer quasilinearer Differentialgleichungen bei geringer Regularität der Lösung
Authors: Kosler R. 
Published: May 2007

AbstractBetrachtet werden nicht notwendig stark elliptische quasilineare Differentialgleichungen zweiter Ordnung in zwei Dimensionen. Unter schwachen Regularitätsbedingungen für die Lösung wird die Konvergenz der Methode der finiten Elemente für die Energienorm und für die Maximumnorm nachgewiesen.
Shock Formation Distance in a Two‐Dimensional Steady Supersonic Flow Over a Concave Corner in Radiative Magnetogasdynamics
Authors: Sharma V. D. , Shyam R. , Singh L. P. 
Published: May 2007

AbstractUsing the theory for the propagation of wavefronts defined by weak discontinuities, the paper presents an analysis of shock wave formation in a two‐dimensional steady supersonic flow over a concave corner in radiative magnetogasdynamics. Transport equations are derived which lead to the determination of the shock formation distance and also to conditions which ensure that no shock will ever evolve on the wave front. It is assessed as to how the shock formation distance is influenced by (i) the presence of radiative and magnetohydrodynamic effects, (ii) the initial curvature of the concave wall, and (iii) the upstream flow Mach number.
Crack Problem in a Transversely Isotropic Medium with a Penny‐Shaped Crack under Transient Thermal Loading
Authors: Ishida R. 
Published: May 2007

AbstractIn this paper, we deal with a theoretical approach to find stress intensity factors for transient thermal loading in an infinite transversely isotropic elastic medium with a penny‐shaped crack the surfaces of which are subjected to a sudden change of temperature. Variations of the stress intensity factors with time are calculated and illustrated in figures.
Über die Wirkung ungleichförmiger Dämpfung bei Kombinationsresonanzen zweiter Art
Authors: Füllekrug U. , Behr D. 
Published: May 2007

AbstractBei der Untersuchung der kinetischen Stabilität elastischer Systeme wird man auf rheolineare Differentialgleichungssysteme geführt. Wenn hierbei gewisse Beziehungen zwischen den Eigenfrequenzen und der Frequenz der Parametererregung bestehen, treten breite Instabilitätsgebiete mit unbeschränkt wachsenden Lösungen auf. In dem Instabilitätsbereich, der als Kombinationsresonanz zweiter Art und erster Ordnung bezeichnet wird, kann eine Zunahme der Dämpfung auch destabilisierend wirken. Zur genaueren Untersuchung dieses Phänomens wird ein einfaches parametererregtes Schwingungssystem betrachtet. Die Lösung der Bewegungsgleichungen erfolgt näherungsweise mit dem Verfahren der langsam veränderlichen Amplitude. Einen besonderen Aufschluß über das Stabilitätsverhalten gibt der Verlauf der charakteristischen Exponenten in der komplexen Ebene. Ist die Frequenzbeziehung für eine Kombinationsresonanz zweiter Art und erster Ordnung exakt erfüllt, dann hat jede Erhöhung der Dämpfung eine weitere Stabilisierung zur Folge. In der Nachbarschaft dieser Frequenzbeziehung gilt dies jedoch nicht mehr. Der Verlauf der charakteristischen Exponenten zeigt bei gleichförmiger Dämpfung einen charakteristisch anderen Verlauf als bei ungleichförmiger Dämpfung. Hiermit lassen sich der destabilisierende Einfluß ungleichförmiger Dämpfung und die niedrigeren Stabilitätsgrenzen erklären.
Die zweiparametrige Matrizeneigenwertaufgabe
Authors: Schneider J. 
Published: May 2007

AbstractDie punktweise Lösung mehrparametriger Eigenwertaufgaben ist aufwendig und von nur geringem qualitativem Aussagewert. Dagegen ermöglicht die Kenntnis von Asymptoten, von Steigungen und Krümmungen in einigen Punkten sowie von Einschließungsgebieten der Eigenkurven einen schnelleren Überblick und erleichtert ihre rasche Konstruktion. Abgeleitet werden solche und ähnliche Hilfsaussagen sämtlich aus der charakteristischen Gleichung des Problems, deren explizite Aufstellung jedoch stets vermieden wird.
A Method to Solve Systems of Nonlinear Equations with Singularities
Authors: Schulze R. 
Published: May 2007

AbstractWe investigate a fast‐convergent derivation‐free method for computing zeros of systems of nonlinear equations with singularities which, in general, needs fewer assumptions than the Newton‐like methods applied usually, and which has proved to be highly efficient by lots of examples. First we transform an arbitrary zero problem into an equivalent, in general under‐determined, zero problem. Then we consider a possibility to transform a zero problem into a possibly globally convergent fixed point form by means of a suitable matrix. We show several possibilities to characterize this matrix. Since the pure Banach iteration provides only linear convergence order of the iterated sequence, we speed up the procedure by means of limit value extrapolation so that we finally obtain a quadratic order of convergence.
Berechenbare Fehlerschranken für ein Eigenpaar unter Einschluß von Rundungsfehlern bei Verwendung des genauen Skalarprodukts
Authors: Alefeld G. 
Published: May 2007

AbstractIn der vorliegenden Arbeit wird, ausgehend von einer Näherung für ein Matrizeneigenpaar mit einem algebraisch einfachen Eigenwert, zunächst eine Einschließung für den Eigenwert und für die Komponenten des dazugehörigen Eigenvektors berechnet. Daran anschließend wird ein Verfahren eingeführt, welches es gestattet, diese Schranken (bei rundungsfehlerfreier Rechnung) beliebig genau zu verbessern. Schließlich wird diskutiert, wie sich dieses Verfahren bei Berücksichtigung von Rundungsfehlern verhält. Dabei setzen wir voraus, daß das von U. Kulisch [3] eingeführte genaue Skalarprodukt zur Verfügung steht. Zwei numerische Beispiele schließen die Arbeit ab.
Zur Konstruktion vollständiger Folgen von Näherungsräumen für Galerkin‐Differenzenverfahren
Authors: Prochnow D. 
Published: May 2007

AbstractIn Hinsicht auf die Galerkin‐Differenzenmethode zur Lösung partieller Differentialgleichungen werden Bedingungen für die Konstruktion vollständiger Folgen von Näherungsräumen angegeben. Die Vollständigkeitsdefinition von Krasnoselsky wird auf den Fall nichtkonformer Approximation ausgedehnt. Zerlegungstheoreme werden bewiesen und Vollständigkeitsresultate in Hilbert‐Räumen bei nichtkonformer Approximation diskutiert. Zur Veranschaulichung der erzielten Resultate werden divergenzfreie Vektorfelder konstruiert.
Konvergenzfaktoren von Mehrgitterverfahren für Probleme der ebenen, linearen Elastizitätstheorie
Authors: Jung M. 
Published: May 2007

AbstractEs wird ein Mehrgitter‐Algorithmus zur Lösung ebener linearer Elastizitätsprobleme vorgeschlagen. Dabei gelingt es, für die Zweigittermethode den Konvergenzfaktor zu berechnen und seine Abhängigkeit von der Poissonschen Querkontraktionszahl sowohl für den ebenen Spannungs‐ als auch für den ebenen Verzerrungszustand anzugeben. Weiter werden Abschätzungen für die Konvergenzrate des Mehrgitter‐Algorithmus dargelegt.
Finite Compression of a Foam Rubber Support System Subjected to Impact Loading
Authors: Tait R. J. , Haddow J. B. 
Published: May 2007

AbstractThe impact loading of a highly compressible hyperelastic layer in uniaxial compression is considered. The problem is applicable to the use of a foam rubber layer attached to a package to prevent damage when the package is dropped. A constitutive equation, proposed by Blatz and Ko [1], for foam rubber is assumed for the layer. Wave propagation effects are neglected.
Motorrechnung im X1+3+3
Authors: Heinz C. 
Published: May 2007

AbstractEs wird ein leicht handzuhabender, der Vektorrechnung nachgebildeter Kalkül für die Motorrechnung in einem metrischen Raum M1+3+3 mit 1 + 3 translatorischen und drei komplexen (d. h. sechs reellen) rotatorischen Dimensionen entwickelt. Die Ergebnisse werden zur Bildung einer Analysis in einem Punktraum X1+3+3 verwendet. Anwendungen auf die Mechanik werden in späteren Arbeiten gegeben werden.
Lower Bounds for the Resonant Frequencies of Nonuniform Frame Structures
Authors: Beattie C. 
Published: May 2007

AbstractThe theory and practice of computing rigorous lower bounds to eigenvalues through the methodology of intermediate problems is extended to general frame structures with nonprismatic beam elements. Intermediate operator constructions for each substructure are used to ensure bounding of the actual resonances from below. The assembly of the elemental intermediate problems into a global dynamic stiffness matrix is discussed together with computational results that illustrate the method applied to a simple planar frame.
An Adaptive Method for Linear Parabolic Differential Equations
Authors: Reiher Th. 
Published: May 2007

AbstractIn the numerical solution of partial differential equations the problem of finding a suitable grid arises. In this paper an adaptive algorithm for the solution of one linear parabolic equation is proposed. This algorithm is based on the result, that the local error of the method can be represented as the sum of the local error in the time variable and that one in the space variable and that both can be estimated separately. So the method works with separated mesh refinement of the space and error control of the time stepsize.
Accurate Numerical Approximations of Eigenfrequencies and Eigenfunctions of Elliptic Membranes
Authors: Hettich R. , Haaren E. , Ries M. , Still G. 
Published: May 2007

AbstractIn earlier papers [3, 4] a defect‐minimization method was proposed to compute approximate eigenfunctions of membranes by means of a parametric semi‐infinite optimization problem. The method gives approximations and error bounds of eigenvalues and eigenfunctions. An algorithm based on this method has been implemented for the special case of elliptic membranes with variable eccentricity. In this paper we show that by this method we obtain very accurate results even for eccentricities near one. In addition the method is very appropriate to study the behavior of eigenfunctions.
Approximation der Verteilung linearer Funktionale schwach korreliert verbundener Vektorprozesse – Anwendung auf Schwingungsdifferentialgleichungen
Authors: vom Scheidt J. , Wöhrl U. 
Published: May 2007

AbstractSchwach korreliert verbundene Vektorprozesse haben die Eigenschaft, daß deren Werte in einem festen Beobachtungspunkt nur die Werte des Prozesses beeinflussen, deren Argumente in einer ε‐Umgebung dieses festen Punktes enthalten sind. In dieser Arbeit werden lineare Funktionale solcher Vektorprozesse untersucht. Die Momente und die Verteilungsdichten der Funktionale werden als Entwicklungen nach Potenzen der Korrelationslänge ε berechnet. In erster Näherung erhält man Gaußsche Verteilungen. Die Resultate werden auf Schwingungsdifferentialgleichungssysteme mit stochastischer Erregung angewendet.
On Optimal Control of Vehicle Vibration by Varying Traversal Velocity
Authors: Zayats O. , Palmov V. , Saranchuk V. 
Published: May 2007

AbstractThe paper investigates optimal changing laws for traversal vehicle velocity, which ensure maximum (minimum) of vertical vibration variance. The solution is given in detail for a one‐degree‐of‐freedom model when the road undulation is a stationary normal exponential‐correlated process. The results obtained enable to choose the velocity rationally and to establish variance changing limits in common case.
Non‐Equidistant Generalizations of the Gushchin‐Shchennikov Scheme
Authors: Vulanović R. 
Published: May 2007

AbstractThe numerical solution of singularly perturbed boundary value problems with turning points is considered. Some modifications and non‐equidistant generalizations of the Gushchin‐Shchennikov finite‐difference scheme are introduced. Both, the stability and the second order consistency are proved. Numerical examples are given.
Ergänzungen zur Lösung des turbulenten Freistrahlproblems der Grenzschichttheorie
Authors: Schultz‐Piszachich W. 
Published: May 2007

AbstractDie Lösung des Freistrahlproblems nach der asymptotischen Theorie von H. Schlichting wird durch Berechnung der turbulenten Normalspannungen, des mittleren Druckes und der turbulenten Energiedissipationsrate ergänzt. Eine verallgemeinerte Lösung von G. Seifert wird durch Einführung expliziter Ausdrücke für die Achsengeschwindigkeit und Halbwertbreite konkretisiert. Damit können die mittleren Geschwindigkeiten und die turbulente Schubspannung auch im Übergangsbereich hinter dem Strahlkern vollständig berechnet werden. Die Grundgleichungen der turbulenten Strahlströmung werden im Rahmen der Grenzschichttheorie formuliert und integriert. Der Theorie der ähnlichen Lösungen, wo keine Stromfunktion angegeben wird, wird neu das selbstkonsistente Strömungsfeld als theoretische Grundlage zur Berechnung der mittleren Geschwindigkeitsprofile gegenübergestellt. Die so ermittelte Stromfunktion stellt bereits die Problemlösung dar. Die Stromlinien der im Mittel stationären Strömung können damit neu berechnet werden.
Attraktorlokalisierung des Lorenz‐Systems
Authors: Leonov G. A. , Bunin A. I. , Koksch N. 
Published: May 2007

AbstractIn the present paper that region, in which the (minimal) attractor [2, 3] is situated, is localized in the phase space of the Lorenz system [1, 2] by means of Lyapunov's second method. Being based on these estimations and the results of paper [4] a sufficient condition is given that separatrix loops of the saddle x = y = z = 0 are missing. Comparison of the bounds for the attractor obtained analytically in this paper with the numerical results by E. Lorenz [1] shows that for certain parameter regions these estimations practically can not be augmented.
Finite‐Difference Schemes for Parabolic Problems with First and Mixed Second Derivatives
Authors: Voigt W. 
Published: May 2007

AbstractFor a half‐linear parabolic differential equation with first derivatives and mixed second derivatives a finite‐difference scheme is proposed which does not need a bound for the step‐size h but has approximation of order two. The principle is based on the introduction of an artificial Reynolds‐number. A numerical example is given, where a comparison of the given method with an already known method is provided.
The Solution of Plane Problems of Wave Loaded Cracks by an Integral Equation Method
Authors: Zhang Ch. , Gross D. 
Published: May 2007

AbstractThe plane problem of straight cracks in an infinite elastic region loaded by time harmonic waves is considered. Using the representation theorem for the displacements the problem is formulated in terms of integral equations for the unknown displacement discontinuity along the cracks. They can be solved by a suitable Galerkin method. Numerical results for the dynamic stress intensity factors of various P‐ or SV‐wave loaded crack configurations are presented and discussed.
Determination of anisidine value in thermally oxidized palm olein by fourier transform infrared spectroscopy
Authors: Che Man Y. B. , Setiowaty G. 
Published: May 2007

AbstractFourier transform infrared (FTIR) spectroscopy with transmission cell is described to predict anisidine value of palm olein. The calibration set was prepared by mixing the thermally oxidized palm olein and the unoxidized palm olein with certain ratios (w/w) covering a wide range of anisidine values. A partial least square (PLS) regression technique was employed to construct a calibration model. This model was further accomplished by a validation step. The standard error of prediction found was 0.51. The precision of this method was shown to be comparable to the accuracy of the American Oil Chemists’ Society method used for measurement of anisidine value, with coefficient of determination (R2) of 0.99. The study showed that mid‐band FTIR spectroscopy combined with a PLS calibration technique is a versatile, efficient, and accurate technique for the estimation of anisidine value of palm olein within about 2 min with less than 2 mL of sample.
Central Asia: Managing the delicate balance between the “discourse of danger,” the “Great Game,” and regional problem solving
Authors: Sandole Dennis J.D. 
Published: May 2007

This article concludes this special issue of Communist and Post-Communist Studies by summarizing the various contributions and noting their commonalties as well as dissimilarities. The primary themes are the various problems in need of solution in Central Asia and the surrounding “neighborhood” (e.g., Afghanistan), including identity-driven conflicts and various ways of handling them.
The article reaches out from the academic researchers who have contributed the articles, to policymakers, especially in the U.S., who may be concerned with identifying and solving the problems of Central Asia and its neighborhood, noting the “unintended consequences” that may befall them for what they do or do not do in the region.
The Decembrists and the Concept of a Civic Nation
Authors: Rabow-Edling Susanna 
Published: May 2007

Long live the constitution! Long live the republic! Long live the people! Perish the nobility and the rank of the czar!Nationalism in the East has long been considered to be different from nationalism in the West. Although Hans Kohn's famous dichotomy has been challenged, it still determines the way most people look at Eastern nationalism. Nationalism in the East is seen as authoritarian, ethnic and cultural in contrast to the democratic, civic and political nationalism of the West. According to the common view, Western nationalism is based on modern liberal, constitutional ideas, which makes it democratic, while Eastern nationalism is based on cultural belonging, which makes it conservative or regressive and hostile to foreign influence.
Light-Dependent Regulation of Cell Division inOstreococcus: Evidence for a Major Transcriptional Input
Authors: Moulager Mickael , Monnier Annabelle , Jesson Béline , Bouvet Régis , Mosser Jean , Schwartz Christian , Garnier Lionel , Corellou Florence , Bouget François-Yves 
Published: May 2007

AbstractCell division often occurs at specific times of the day in animal and photosynthetic organisms. Studies in unicellular photosynthetic algae, such as Chlamydomonas or Euglena, have shown that the photoperiodic control of cell division is mediated through the circadian clock. However, the underlying mechanisms remain unknown. We have studied the molecular basis of light-dependent control of cell division in the unicellular green alga Ostreococcus. We found that cell division obeys a circadian oscillator in Ostreococcus. We provide evidence suggesting that the clock may, at least in part, regulate directly cell division independently of the metabolism. Combined microarray and quantitative real-time reverse transcription-polymerase chain reaction analysis of the main core cell cycle gene expression revealed an extensive transcriptional regulation of cell division by the photoperiod in Ostreococcus. Finally, transcription of the main core cell cycle genes, including cyclins and cyclin-dependent kinases, was shown to be under circadian control in Ostreococcus, suggesting that these genes are potential targets of the circadian clock in the control of cell division.
Evolution of Flavone Synthase I from Parsley Flavanone 3β-Hydroxylase by Site-Directed Mutagenesis
Authors: Gebhardt Yvonne Helen , Witte Simone , Steuber Holger , Matern Ulrich , Martens Stefan 
Published: May 2007

AbstractFlavanone 3β-hydroxylase (FHT) and flavone synthase I (FNS I) are 2-oxoglutarate-dependent dioxygenases with 80% sequence identity, which catalyze distinct reactions in flavonoid biosynthesis. However, FNS I has been reported exclusively from a few Apiaceae species, whereas FHTs are more abundant. Domain-swapping experiments joining the N terminus of parsley (Petroselinum crispum) FHT with the C terminus of parsley FNS I and vice versa revealed that the C-terminal portion is not essential for FNS I activity. Sequence alignments identified 26 amino acid substitutions conserved in FHT versus FNS I genes. Homology modeling, based on the related anthocyanidin synthase structure, assigned seven of these amino acids (FHT/FNS I, M106T, I115T, V116I, I131F, D195E, V200I, L215V, and K216R) to the active site. Accordingly, FHT was modified by site-directed mutagenesis, creating mutants encoding from one to seven substitutions, which were expressed in yeast (Saccharomyces cerevisiae) for FNS I and FHT assays. The exchange I131F in combination with either M106T and D195E or L215V and K216R replacements was sufficient to confer some FNS I side activity. Introduction of all seven FNS I substitutions into the FHT sequence, however, caused a nearly complete change in enzyme activity from FHT to FNS I. Both FHT and FNS I were proposed to initially withdraw the β-face-configured hydrogen from carbon-3 of the naringenin substrate. Our results suggest that the 7-fold substitution affects the orientation of the substrate in the active-site pocket such that this is followed by syn-elimination of hydrogen from carbon-2 (FNS I reaction) rather than the rebound hydroxylation of carbon-3 (FHT reaction).
A Chlorophyll-Deficient Rice Mutant with Impaired Chlorophyllide Esterification in Chlorophyll Biosynthesis
Authors: Wu Ziming , Zhang Xin , He Bing , Diao Liping , Sheng Shenglan , Wang Jiulin , Guo Xiuping , Su Ning , Wang Lifeng , Jiang Ling , Wang Chunming , Zhai Huqu , Wan Jianmin 
Published: May 2007

AbstractChlorophyll (Chl) synthase catalyzes esterification of chlorophyllide to complete the last step of Chl biosynthesis. Although the Chl synthases and the corresponding genes from various organisms have been well characterized, Chl synthase mutants have not yet been reported in higher plants. In this study, a rice (Oryza Sativa) Chl-deficient mutant, yellow-green leaf1 (ygl1), was isolated, which showed yellow-green leaves in young plants with decreased Chl synthesis, increased level of tetrapyrrole intermediates, and delayed chloroplast development. Genetic analysis demonstrated that the phenotype of ygl1 was caused by a recessive mutation in a nuclear gene. The ygl1 locus was mapped to chromosome 5 and isolated by map-based cloning. Sequence analysis revealed that it encodes the Chl synthase and its identity was verified by transgenic complementation. A missense mutation was found in a highly conserved residue of YGL1 in the ygl1 mutant, resulting in reduction of the enzymatic activity. YGL1 is constitutively expressed in all tissues, and its expression is not significantly affected in the ygl1 mutant. Interestingly, the mRNA expression of the cab1R gene encoding the Chl a/b-binding protein was severely suppressed in the ygl1 mutant. Moreover, the expression of some nuclear genes associated with Chl biosynthesis or chloroplast development was also affected in ygl1 seedlings. These results indicate that the expression of nuclear genes encoding various chloroplast proteins might be feedback regulated by the level of Chl or Chl precursors.