bluuebunny/crossref_metadata_2025 huggingface dataset:
Zur nichtlinearen Theorie des Wellenwiderstandes für kleine Froudesche Zahlen
Authors: Zwick W.
Published: June 2007

Es wird eine nichtlineare Methode zur Berechnung des Wellenwiderstandes von Körpern bei stationärer Umströmung in einer flachen Flüssigkeit entwickelt. Dabei werden Methoden der Potentialtheorie angewendet. Durch Belegen der Randflächen mit Quellen und Senken erhält man eine Integraldarstellung für die induzierte Geschwindigkeit, und die Randwertaufgabe läßt sich zu einem System von Integro‐Differentialgleichungen umformen. Nach dem Anwenden numerischer Methoden lassen sich diese Integralgleichungen durch algebraische Gleichungen approximieren, die für kleine Froudesche Zahlen iterativ gelöst werden können. Dabei ergeben die numerischen Rechnungen, daß für kleine Froudesche Zahlen bei symmetrischen Körpern der Wellenwiderstand verschwindet, die Belegungsfunktionen antisymmetrische und die Form der freien Oberfläche symmetrische Eigenschaften aufweisen. Diese qualitativen Eigenschaften der Lösung können auch analytisch begründet werden.
Die schubbeanspruchte Kerbe im Cosseratkörper
Authors: Neuber H.
Published: June 2007

Für das schubbeanspruchte Cosseratprisma, das eine tiefe Kerbe mit ebenen Flanken und kreiszylindrischem Grund enthält, wird die Lösung des Spannungsverteilungsproblems in geschlossener Form angegeben.
Slow Steady Axial Flow of a Rivlin‐Ericksen Fluid in a Wavy Annulus with Heat‐Transfer
Authors: Mathur M. N. , Bhatnagar R. K.
Published: June 2007

The problem of heat transfer due to the steady slow motion of a Rivlin‐Ericksen fluid in the annular space between two wavy cylinders has been considered. Taking the deformation of the boundaries to be small, the equations of continuity, momentum and energy have been solved using the perturbation technique. The solution for the velocity field is employed to study the nature of the temperature distribution under two types of thermal boundary conditions. Non‐Newtonian parameters affect the velocity field, the stresses and the temperature field. The flow pattern and the temperature distribution are somewhat similar in nature to that observed in case of the way cylindrical tube in reference [5].
Magnetohydrodynamic Unsteady Free Convection
Authors: Chawla Sahib Singh
Published: June 2007

The unsteady free convection flow from an infinite vertical plate, under the action of a transverse magnetic field, is analysed in the case when the plate temperature undergoes a thermal transient. The solution is obtained by Laplace transform technique. The applied field is found to induce a wave‐dominated flow pattern. The flow within the viscous and thermal boundary layers is also considered. At all stages of the motion the shearing stress at the plate is found to be larger than the corresponding value in the non‐magnetic case, although the viscous part is smaller.
Die Behandlung von Randwertproblemen für zylindersymmetrische Druckwellen kleiner Amplitude
Authors: Heynatz J. T.
Published: June 2007

Für zylindersymmetrische Druckwellen kleiner Amplituden werden Randwertprobleme gelöst, bei denen die Berechnung auslaufender (Teil A) oder einlaufender (Teil B) Wellenzüge erforderlich is. Es. handelt sich um die Reflexion von Wellen bei Vorgabe der Druckstörung oder der Geschwindigkeit am Reflexionsort und um die Strömungsvorgänge beim Aneinandersetzen von ebenen und zylindersymmetrischen sowie von divergenten und konvergenten Wellen. Zylinderwellen mit aus‐ oder mit einlaufender Front weisen grundsätzliche Unterschiede, auf, die voneinander abweichende Behandlungsmethoden erzwingen. Die Erfüllung von Randwertvorgaben für auslaufende Wellen führt auf Volterrasche Integralgleichungen erster Art, die in der Umgebung von Wellenfrontreflexionen analytisch und für beliebige Zeiten numerisch gelöst werden. Bei einlaufenden Wellen kann man die eine der auftretenden zwei Wellenfunktionen mit Hilfe einer Frontbedingungen durch die andere ausdrücken. Die Randwertvorgaben führen auf Fredholmsche Integralgleichungen, die numerisch gelöst werden. Aus der Frontbedingung folgen allgemeine Reflexionsgesetze für Wellenfronten. Als Beispiele werden Druck‐ und Geschwindigkeitsverläufe für Wellenreflexionen am offenen Ende und an einer festen Wand sowie für den Übergang einer ebenen in eine zylindersymmetrische Welle angegeben.
Linearized Theory of Nonstationary Cascades at Fully Stalled or Supercavitated Conditions
Authors: Sisto F.
Published: June 2007

Nonsteady lift and moment expressions are formulated for an infinite two‐dimensional cascade of foils experiencing periodic deformations about an equilibrium state which may be interpreted as either fully stalled airfoils or supercavitated hydrofoils. Fundamental assumptions are: 1) flow is incompressible and inviscid, 2) displacements are small, 3) foils are flat plates of negligible thickness, 4) the separated (or cavitated) wakes are taken to be straight slits extending from each profile leading edge and trailing edge to downstream infinity, 5) the boundary conditions are satisfied on the two sides of each slit which is assumed to be stationary for this purpose, 6) the mean incidence is considered to be large enough so that the separation points at leading and trailing edges remain fixed during the cycle of oscillation, and 7) there is a constant phase angle between the motion of adjacent foils. The flow problem is solved by conformal mapping using the acceleration potential.
Zur Fließgrenze bei allgemeiner Verfestigung
Authors: Backhaus G.
Published: June 2007

Die bei plastischer Verformung kristalliner Werkstoffe auftretende Verfestigung wird auf drei Grundtypen der Verfestigung zurückgeführt: Die isotrope, die kinematische und die anisotrope Verfestigung. Ausgehend von bekannten Ansätzen zur analytischen Erfassung dieser drei Verfestigungsgesetze wird eine Fließbedingung abgeleitet, die den Einfluß der Verformungsgeschichte berücksichtigt und drei von der „Vergleichsdehnung”︁ abhängige Materialgrößen enthält. Die Anwendbarkeit der Fließbedingung auf zyklische plastische Verformungen wird erörtert, im Schrifttum veröffentlichte Versuchsergebnisse werden ausgewertet. Der Einfluß der Verformungsgeschichte auf die Gestalt der Fließgrenze wird für einen speziellen ebenen Verformungsvorgang quantitativ ermittelt.
Die elastostatischen Greenschen Tensoren für den Halbraum mit Anwendungen auf Wärmespannungsprobleme
Authors: Jentsch L.
Published: June 2007

Die elastostatischen Greenschen Tensoren 1. und 2. Art werden berechnet, indem für die Spalten des regulären Anteils verallgemeinerte elastische Potentiale der Doppel‐ bzw. Einfachbelegung angesetzt werden. Die Belegungsdichten dieser Potentiale werden aus singulären Integralgleichungssystemen mittels Fouriertransformation ermittelt. Durch Divergenzbildung der Zeilen der Tensoren kommt man zu den bekannten Formeln für das Verschiebungsfeld unter der Wirkung eines Kompressionszentrums im Innern des Halbraumes bei starrer bzw. spannungsfreier Oberfläche, die sich auf Wärmespannungsprobleme anwenden lassen. Die Verformung des Halbraumes mit zwei im Innern desselben sich ausdehnenden Kugeln bei starrer und spannungsfreier Oberfläche wird als Anwendung explizit berechnet.
Diffraction of a plane pulse by a closed crack at the interface of elastic solids
Authors: Freund L. B. , Achenbach J. D.
Published: June 2007

Transient diffraction of a plane dilatational pulse is studied. The diffracting surface is a semi‐infinite closed crack at the interface of two elastic solids of different material properties. The problem is solved by application of Laplace transform methods and the Wiener‐Hopf technique. The inverse transforms are evaluated by means of Cagniard's method. The displacement potentials in each solid are obtained in the form of real integrals. For an incident dilatational impulse, closed form expressions are derived for the displacement field. For this case the displacements at the interface are shown in graphs, and they are compared with the corresponding displacements when the two solids are of equal material properties.
The solution for concentrated loads on shells by means of Thompson functions
Authors: Łukasiewicz S. S.
Published: June 2007

The paper deals with the displacements and stresses in arbitrary shells of positive Gauss curvature subjected to concentrated loads. The solutions for normal and tangential forces as well as for a bending moment applied to the shell are derived by means of Fourier integrals.
Ein Beitrag zur linearisierten Theorie des periodisch instationär angeströmten Unterwassertragflügels
Authors: Simmgen M.
Published: June 2007

Zur quellenmäßigen Darstellung des Beschleunigungs‐ bzw. des Geschwindigkeitspotentials eines periodisch angeströmten Unterwasserflügels benötigt man das Potential einer parallel angeströmten pulsierenden räumlichen Unterwasserquelle (G2) bzw. mit pulsierenden Quellen belegten Halbgeraden (H2). Durch Überlagerung von entsprechenden ebenen Lösungen wird zunächst für G2 ohne Verwendung des Scheinreibungskoeffizienten eine Doppelintegralform abgeleitet. In der endgültigen Form werden G2 und H2 sowie die sich als Spezialfall ergebenden stationären Potentiale G1 und H1 durch Einfachintegrale dargestellt. Sie lassen sich dann ohne besondere Schwierigkeiten für große Froudesche Zahlen entwickeln, worauf am Schluß noch kurz eingegangen wird.
Intrinsic equations governing the flow of a steady, incompressible, viscous fluid
Authors: Suryanarayan E. R.
Published: June 2007

Considering a vortex line as a C3 curve in the euclidean space, equations, governing the flow of a steady incompressible fluid are expressed in the intrinsic form. These intrinsic relations are applied to derive some geometric properties of viscous fluid flows, and to study a class of flows whose vortex lines form a family of right circular helices.
Zur Lösung einer Klasse konvexer Minimumprobleme der Plastizitätstheorie
Authors: Gajewski H.
Published: June 2007

Mit Hilfe eines Satzes von Browder läßt sich das Minimumproblem: „Im Hilbertraum die Projektion eines gegebenen Elements auf die Fixpunktmenge eines nichtexpansiven Operators zu ermitteln”︁, konstruktiv lösen. Es wird eine allgemeine Klasse von Fixpunktmengen nichtexpansiver Operatoren angegeben. Derartige Mengen treten als Mengen statische zulässiger Spannungsfelder (MszS) in der Plastizitätstheorie auf. Das Problem der Projektion geeigneter, äußere Belastungen repräsentierender Elemente auf die MszS erweist sich auf der Grundlage eines von Haar und v. Kármán aufgestellten Minimalprinzips als identisch mit dem Problem der Ermittlung der Spannungsverteilung in einem elastisch‐idealplastischen Körper, das so eine relativ einfache Lösung findet.
The Minimizing Strain‐Rate History and the Resulting Greatest Lower Bound on Work in Linear Viscoelasticity
Authors: Breuer S.
Published: June 2007

The paper considers isothermal deformations of a linear viscoelastic material in simple tension or compression. The relaxation modulus defining the material is assumed to be a sum of exponential functions, but need not necessarily be a monotonic function. The greatest lower bound on the work required to deform the material from its virgin state in a given time interval (0, T) is determined – independently of the strain‐rate history – in terms of T, the strain at the time T, and the constants entering the definition of the relaxation modulus. The optimum strain‐rate history, which actually produces the greatest lower bound on the work, is also determined. The results may be extended to the general deformations of a linear anisotropic viscoelastic solid.
Turbulente Grenzschichten in Ablösungsnähe
Authors: Szablewski W.
Published: June 2007

Auf der Grundlage der in einer vorangehenden Arbeit entwickelten Konzeption wird das Verhalten turbulenter Grenzschichten in Ablösungsnähe beschrieben. Für Äquilibrium‐Grenzschichten erhält man einfache explizite Formeln, die in weitgehender Übereinstimmung mit Messungen von F. H. Clauser und B. S. Stratford stehen. Eine Feststellung von Belang ist, daß die Ermittlung des lokalen Reibungswiderstandes in Ablösungsnähe mittels des logarithmischen Wandgesetzes nicht möglich ist.
Zur Bestimmung des Verzerrungstensors aus der Messung plastischer Verformungen
Authors: Backhaus G.
Published: June 2007

Die experimentelle Ermittelung des Tensors der Verzerrungen bzw. Verzerrungsgeschwindigkeiten bei plastischen Verformungen ist für die Analyse von Verformungsvorgängen von Bedeutung. Bei der sogen. visioplastischen Methode wird die Verformung z. B. durch ein rechtwinkliges Liniengitter sichtbar gemacht, das auf der Körperoberfläche oder in einem Symmetrieschnitt angeordnet wird. Für inhomogene und instationäre Verformungsvorgänge wird ein Verfahren angegeben, das aus den gemessenen Verschiebungen der Schnittpunkte der Gitterlinien die natürlichen Verzerrungsgeschwindigkeiten zu ermitteln gestattet. Die Genauigkeit des Verfahrens wird anhand eines Verformungsbeispiels untersucht.
Grenzen von Mitnahmebereichen. Periodische Lösungen von Differentialgleichungen mit Schaltstellen
Authors: Schwertassek R.
Published: June 2007

Es werden Mitnahmeerscheinungen am Beispiel einer stückweise linearen Differentialgleichung studiert. Dazu werden im ersten Teil der Arbeit Differentialgleichungen behandelt, in denen Glieder mit stückweise analytischen Funktionen vorkommen. Mit Hilfe der Lösungen solcher Differentialgleichungen werden Punkttransformationen definiert, so daß die Transformationstheorie und die Störungsrechnung zur Bestimmung periodischer Lösungen verwendet werden können; mit der Methode der impliziten Funktionen wird geprüft, ob die gefundenen Lösungen existieren. Im zweiten Teil werden die entwickelten Methoden auf eine spezielle, eine stückweise lineare, Differentialgleichung angewendet. An diesem Beispiel werden Mitnahmeerscheinungen untersucht, zunächst analytisch, für kleine Parameter, und dann, numerisch, auch für nicht kleine Parameter.
Post Buckling Behavior of Axially Compressed Core‐Filled Cylinders
Authors: Myint‐U T.
Published: June 2007

The post buckling behavior of an axially compressed corefilled circular cylindrical shell is presented. The soft elastic core is represented by the Pasternak foundation model which is a Winkler foundation model with shear interactions. The Ritz energy method is employed to obtain the load‐deformation relationship. The stabilizing effect of soft core on the buckling strength of shell is illustrated.
Die Biegeschwingungen von Rechteckplatten mit großen Amplituden
Authors: Hung Nguyen‐Xuan
Published: June 2007

Ausgehend von den Gleichungen von Th. v. Kármán, werden Plattenschwingungen mit der Methode der Störungsrechnung untersucht. Die Lösung wird mit Ergebnissen aus der Galerkinschen Methode bei Anwendung eines eingliedrigen Ansatzes verglichen. Es wird gezeigt, daß in der ersten Näherung die beiden Methoden dieselben Ergebnisse liefern. In der zweiten Näherung unterscheiden sich die beiden Ergebnisse wesentlich.
Buckling of a Beam on a Wieghardt‐Type Elastic Foundation
Authors: Smith T. E.
Published: June 2007

The paper gives a computation of the buckling load for a rod with pinned ends and elastic embedding according to Wieghardt. The influence of shearing stresses on the bending is taken into account. The result is compared with the buckling load holding for elastic embedding according to Winkler. The important differences in the results of two theories are emphasized.
A Note on Physical Components
Authors: Williams G. , Hector D. L.
Published: June 2007

Many differing definitions of physical components of tensors exist in the literature. Most of these agree when defined relative to orthogonal coordinate systems. The purpose of this paper is to compare existing definitions and to clarify the situation in an oblique coordinate system. The conclusion is reached that any mapping of the tensor into the relevant Rn which is one to one, structure preserving and having physical significance can define physical components.
Circular Crack Problem for Initialy Stressed Neo‐Hookean Solid
Authors: Kurashige M.
Published: June 2007

For an axisymmetric problem under incremental deformation theory for neo‐Hookean solid, a basic equation to be satisfied by a displacement function is obtained and the components of incremental displacement, strain and stress are expressed by the displacement function. Using the basic equation and expressions, the distribution of incremental stress in the neighbourhood of a circular crack with internal pressure in an infinite body under an initial finite deformation owing to all‐around compression is investigated, and the influence of initial stress upon the distribution of incremental stress is presented in the form of curves.
Über die Unstetigkeiten des Interferenzkernes im Integralgleichungssystem für ein in Unterschallströmung harmonisch schwingendes T‐Leitwerk
Authors: Martinez J.
Published: June 2007

Für ein in Unterschallströmung harmonisch schwingendes T‐Leitwerk wird der Interferenzkern des Integralgleichungssystems, welches die Amplitudenfunktionen der Anstellwinkel‐ und Druckverteilung zueinander in Beziehung setzt, untersucht. Für den unstetigen Anteil des Interferenzkernes wird ein geschlossener Ausdruck angegeben. Diese Darstellung ist bei der numerischen Bestimmung der Druckverteilung eines harmonisch schwingenden T‐Leitwerkes anwendbar.
Geometrische Bemerkungen zur Theorie nichtstationärer Gasströmungen
Authors: Sauer R.
Published: June 2007

Bei der nichtstationären eindimensionalen Strömung von Gasen ist bei Beschränkung auf isentropische Zustandsänderungen der Druck p eine Funktion der Zustandsgrößen x1, x2 (x1 = Energie der Masseneinheit = Wärmeinhalt + kinetische Energie, x2 = Strömungsgeschwindigkeit) und die Stromfunktion Ψ eine Funktion von y1, y2 (y1 = Länge, y2 = Zeit). Die Druckfläche p = p (x1, x2) und die Stromfunktionsfläche Ψ = Ψ (y1, y2) sind dabei durch die vorgegebene Strömung in bestimmter Weise aufeinander bezogen. Es wird vorausgesetzt, daß diese Beziehung eine punktweise ein‐eindeutige Abbildung vermittelt. Die geometrischen Eigenschaften dieser Abbildung werden untersucht. Dabei ergeben sich sowohl auf den beiden Flächen als auch in ihren Grundrissen in der x1, x2‐Ebene und der y1, y2‐Ebene bemerkenswerte parallel‐bezogene Paare von Kurvennetzen (anti‐parallele und reziprok‐parallele Kurvennetze).
Lifting‐line Theory of Supercavitating Hydrofoil of Finite Span
Authors: Nishiyama T.
Published: June 2007

Lifting‐line theory is developed for a supercavitating hydrofoil of finite span at non‐zero cavitation number. Main treatments in the paper are enumerated as follous:

Simplification of basic equations in the perturbed flow field for a supercavitating hydrofoil of large aspect ratio shows that two‐dimensionality still holds with respect to an effective angle of attack over the span.

Making use of this result, an integral equation is derived for the circulation distribution over the span at non‐zero cavitation number and then its numerical method of solution is shown.

Foil characteristics are obtained analytically from circulation calculated and also discussed in details in relation to the aspect ratio and cavitation number. Particularly, a three dimensional correction factor is introduced to the supercavitating hydrofoils of finite span.

Comparisons with the experimental data and former theories are made to confirm the appropriateness of the present theory.
Zur Konstruktion invarianter polyedrischer Kegel für gewisse Klassen von reellen Matrizen und deren Ausnutzung für Fehlerabschätzungen beim Eigenwertproblem
Authors: Schwetlick H.
Published: June 2007

Es werden hinreichende Bedingungen dafür angegeben, daß sich eine reelle Matrix mittels einer speziellen Ähnlichkeitstransformation in eine Matrix mit nichtnegativen Elementen überführen läßt. Diese Bedingungen werden verwendet, um mittels der Sätze von Perron und Collatz Fehlerabschätzungen für den betragsgrößten Eigenwert einer Matrix und einen zugehörigen Eigenvektor anzugeben. Dabei muß eine Näherung für diesen Eigenvektor bekannt sein.
Wavemechanics of Compressible Fluids
Authors: Wilhelm H. E.
Published: June 2007

It is shown that the complete set of nonlinear conservation equations for mass, vector momentum, and energy of compressible, dissipation‐free fluids can be transformed into a complex, scalar wave equation. The latter contains only a single nonlinear term which has the meaning of a pressure potential. Thus the transformation leads to a considerable simplification in the mathematical description of compressible fluids. As a concrete illustration of the wavemechanical formulation, the dispersion of acoustic waves is treated briefly.
Linearisierung der instationären, gasdynamischen Gleichung und Diskussion der Voraussetzungen an verschiedenen Fällen
Authors: Sockel H.
Published: June 2007

Die vorliegende Linearisierung der gasdynamischen Gleichung ist allgemein gehalten und kann daher auf alle speziellen Fälle angewendet werden. Anhand von Beispielen wird gezeigt, wie man aus den Randbedingungen den für das Einzelproblem charakteristischen Parameter erhält. Dieser erlaubt eine Abschätzung der Größe des instationären Gliedes im Vergleich zu den anderen Ausdrücken in der Differentialgleichung.
Über die Gewinnung von Optimalitätsbedingungen für nichtkonvexe Optimierungsaufgaben durch Lösung linearer Programme
Authors: Kleinmichel H.
Published: June 2007

Jeder nichtlinearen Optimierungsaufgabe werden zwei lineare Optimierungsaufgaben zugeordnet. Mit den Lösungen der zugeordneten linearen Aufgaben lassen sich einfache Optimalitätsbedingungen für das nichtlineare Ausgangsproblem formulieren.
On a New Variational Principle of Hamiltonian Type for Classical Field Theory
Authors: Djukic Dj. , Vujanovic B.
Published: June 2007

A variational principle of hamiltonian type for various physical phenomena is constructed. Its application to the problems of the nonlinear heat transfer and fluid flow in Eulerian description is shown.
Zur Konstruktion von Bergman‐Operatoren
Authors: Watzlawek W.
Published: June 2007

Für eine bestimmte Klasse linearer partieller Differentialgleichungen zweiter Ordnung wird eine Möglichkeit zur Gewinnung von Bergman‐Operatoren aus gewissen Lösungen der Differentialgleichung angegeben. Für die Spezialfälle der Helmholtzgleichung und einer von K. W. Bauer untersuchten Differentialgleichung ergeben sich von M. Kracht und E. Kreyszig auf andere Weise aus der Riemann‐Funktion erhaltene Operatoren.
Eine allgemeine Aussage über die Stabilität ausgewanderter Schwingungsmittellagen bei determinierter Erschütterung
Authors: Merz E.
Published: June 2007

Alle Untersuchungen über das Auswanderungsverhalten von Schwingungsmeßgeräten und elektrischen Zeigermeßwerken bei determinierten Erschütterungen haben stets auf denselben Stabilitätsentscheid geführt. In dieser Arbeit wird der Nachweis erbracht, daß dieser Stabilitätsnachweis für solche Probleme und auch für allgemeinere Bewegungsgleichungen ähnlichen Aufbaus generell gilt. Die umfangreiche Stabilitätsuntersuchung wird damit wesentlich vereinfacht.
On a Class of Steady Nonrotating Axisymmetric Flows: II
Authors: Rassmussen H.
Published: June 2007

Die in Teil I (ZAMM 51, (1971)) begonnene Untersuchung derjenigen nichtrotierenden stationären, zähen, inkompressiblen und achsensymmetrischen Strömungen, bei denen die Axialkomponente der Geschwindigkeit nur von dem längs der Achse gemessenen Abstand von einem Bezugspunkt abhängt, wird fortgesetzt. Es werden die restlichen beiden Fälle der integrierten Form der maßgeblichen gewöhnlichen Differentialgleichung betrachtet und ihre Lösungen in einem dreidimensionalen Phasenraum studiert.
Eine Schalentheorie endlicher Verformungen und ihre Anwendung zur Herleitung der Stabilitätstheorie
Authors: Başar Y.
Published: June 2007

In der vorliegenden Arbeit werden zuerst für endliche Verzerrungs‐ bzw. Verschiebungsgrößen die Grundgleichungen elastischer Schalentragwerke hergeleitet. Das Materialgesetz wird in zwei verschiedenen Formen vorausgesetzt, die dann zu entsprechenden Gleichgewichtsbedingungen und konstitutiven Gleichungen führen. Die aufgestellte Theorie stützt sich auf die Annahme der Normalenhypothese. Ausgehend von den allgemeinen Gleichungen der nichtlinearen Theorie werden dann die linearen Stabilitätsbeziehungen abgeleitet. Mit Hilfe dieser Grundgleichungen kann das Differentialgleichungssystem zur Stabilitätsuntersuchung von Schalentragwerken mit beliebiger Geometrie und Belastung in abstrakter Weise aufgestellt werden.
Systeme mit linearem Hauptteil und linearen Abschätzungen für die Störfunktion
Authors: Kappel F.
Published: June 2007

In der vorliegenden Arbeit werden Systeme der Gestalt
magnified image
A eine konstante Matrix, betrachtet. Mit Hilfe der direkten Methode Ljapunovs werden lineare Schranken für die Störfunktion g(x, t) angegeben, wobei als Ljapunov‐Funktionen quadratische Formen verwendet werden. Es wird ein numerisch brauchbares Verfahren angegeben, um möglichst günstige Schranken zu erhalten.
Abbrechkriterium für Iterationsverfahren
Authors: Krawczyk R.
Published: June 2007

Die unendliche Folge xn des allgemeinen Iterationsverfahrens zur Lösung einer Operatorgleichung x = T x in einem metrischen Raum wird häufig durch eine endliche Folge x̃n approximiert, welche von der benutzten Rechenanlage abhängt. Es wird ein Abbrechkriterium angegeben, welches die “numerische Konvergenz” im Sinne von [3] garantiert. Dieses Abbrechkriterium wird auf das Newtonsche Verfahren zur Lösung einer Gleichung im Reellen und auf eine lineare Integralgleichung angewandt.
Über reguläre Zerlegungen bei nichtlinearen Abbildungen
Authors: Alefeld G.
Published: June 2007

In [3] hat R. S. Varga den Begriff der regulären Zerlegung einer Matrix eingeführt und damit die Konvergenz einiger Iterationsverfahren zur Auflösung linearer Gleichungssysteme nachgewiesen. In dieser Arbeit sollen diese Ergebnisse in zweierlei Hinsicht verallgemeinert werden: Einerseits werden auch nichtlineare Abbildungen zugelassen, andererseits werden alle Aussagen in einem halbgeordneten Banachraum formuliert und bewiesen. Als konkrete Anwendung ergeben sich unmittelbar Aussagen über die Konvergenz einiger Iterationsverfahren zur Auflösung nichtlinearer Gleichungssysteme im Rn.
Forced Motion of Elastic Cylindrical Rods A Comparison of Two Theories
Authors: Reismann H. , Tsai L.‐W.
Published: June 2007

This investigation considers axial forced motion of elastic rods of finite length, and compares the predictions of elementary red theory (as characterized by the wave equation) with those of an improved theory which accounts for longitudinal as well as radial motions. A specific example of transient forced motion indicates the possibility of considerable differences in the predictions of the two theories.
Effects of Shearing Force and Rotary Inertia to Dynamical Behaviours of Thin Cylindrical Shells Subjected to Impulsive Inner Pressures
Authors: Suzuki S.
Published: June 2007

Behaviours of dynamical stresses and bending moments acting in the cantilevered thin cylindrical shells subjected to impulsive inner pressure are investigated. Cylinder is assumed to be elastic and inner pressure to be expressed as step function with respect to time. In this analysis, shearing force and rotatory inertia are taken into consideration. Relationships between dimensions of a cylinder and dynamic load factors with respect to hoop stress at free end and bending moment at clamped end are studied. From the results of analysis, it became evident that the values of dynamic load factors with respect to hoop stress at free end for the case where two factors are taken into consideration are much different from those for the case where these are neglected.
Simulating Ramsey-Type Fringes in a Pulsed Microwave-Driven Classical Josephson Junction
Authors: Marchese Jeffrey E. , Cirillo Matteo , Grønbech-Jensen Niels
Published: June 2007

We present evidence for a close analogy between the nonlinear behaviour of a pulsed microwave-driven Josephson junction at low temperature and the experimentally observed behaviour of Josephson systems operated below the quantum transition temperature under similar conditions. We specifically address observations of Ramsey-type fringe oscillations, which can be understood in classical nonlinear dynamics as results of slow transient oscillations in a pulsed microwave environment. Simulations are conducted to mimic experimental measurements by recording the statistics of microwave-induced escape events from the anharmonic potential well of a zero-voltage state. Observations consistent with experimentally obtained Ramsey-type oscillations are found in the classical model.
An Audit of the Safe Use of the Mini C-Arm Image Intensifier in the Out-Patient Setting
Authors: HASHAM S. , BURKE F. D. , EVANS S. J. , ARUNDELL M. K. , QUINTON D. N.
Published: June 2007

Mini C-arm image intensifiers are used commonly in surgery of the upper limb. With relatively low doses of emitted ionising radiation, portability and superior quality of image, they are a useful aid to the operating surgeon. However, these benefits are not so often used outside the theatre setting. This paper examines the use of a mini C-arm image intensifier in the out-patient clinic and presents an audit of 100 consecutive out-patients. We reviewed the potential benefits and effects on their care pathway. We also look at the specific radiation protection issues of the mini C-arm image intensifier in the out-patients clinic. We believe use of the mini C-arm image intensifier in the out-patient setting may speed treatment and reduce the cost of treatment.
Can surgery provoke the outgrowth of latent breast cancer? A unifying hypothesis
Authors: Retsky M. W. , Demicheli R. , Hrushesky W. J. M. , Baum M. , Gukas I. D.
Published: June 2007

AbstractTo explain bimodal relapse patterns, we have previously suggested that metastatic breast cancer growth commonly includes periods of temporary dormancy at both the single cell and avascular micrometastasis phases (with 1 year and 2 year half-lives respectively). We further suggested that primary surgery sometimes initiates growth of distant dormant disease accelerating relapse. These iatrogenic events are common in that they occur in over half of all relapses. Surgery induced angiogenesis is mostly confined to premenopausal node positive patients in which case 20% of patients are so affected. We review here how this hypothesis explains a vairety of previously unrelated breast cancer phenomenon including 1) the mammography paradox for women age 40–49 untreated with adjuvant therapy, 2) the particularly high benefit of adjuvant chemotherapy for premenopausal node positive patients, 3) the heterogeneity of breast cancer, 4) the aggressiveness of cancer in young women, 5) the outcome differences with timing of surgery within the menstrual cycle, 6) the common myths regarding cancer spreading “when the air hits it” and treatment “provoking” the tumor, 7) the excess mortality of blacks over whites, and 8) reports from physicians 2000 years ago. In parallel to physicists who have long sought to explain all of physics with a unified field theory, we now suggest temporary dormancy together with surgery induced tumor growth provides a unifying theory for much of breat cancer.
An additional layer in the low‐latitude ionosphere in Indian longitudes: Total electron content observations and modeling
Authors: Thampi Smitha V. , Balan N. , Ravindran Sudha , Pant Tarun Kumar , Devasia C. V. , Sreelatha P. , Sridharan R. , Bailey G. J.
Published: June 2007

The paper presents the observations and modeling of an additional layer in the low‐latitude ionosphere in Indian longitudes. The signatures of the additional layer are observed as ledges or humps between the equatorial ionization anomaly trough and crest (EIA) in the latitudinal profiles of total electron content (TEC), measured using a single ground‐based beacon receiver located at Trivandrum (8.5°N, 77°E, dip 0.5°N) in India. The ground‐based ionograms also show the presence of the so‐called F3 layer for a short duration corresponding to these signatures, and the layer is found to drift upward to the topside ionosphere. The study provides first observational evidence that the so‐called “humps” in the latitudinal variation of TEC are nothing but the upward propagating F3 layer. This conclusion is supported by theoretical modeling using the Sheffield University Plasmasphere Ionosphere Model. It is shown that upward ExB drift and strong equatorward neutral wind (perturbed by atmospheric waves) can produce the humps in the latitudinal variation of TEC through the reduction in the downward diffusion of ionization along geomagnetic field lines. The model results also show that the F3 layer drifts to the topside and forms topside ledges.
Dayside reconnection enhancement resulting from a solar wind dynamic pressure increase
Authors: Boudouridis A. , Lyons L. R. , Zesta E. , Ruohoniemi J. M.
Published: June 2007

It is well known that the Interplanetary Magnetic Field (IMF) is the major contributor to geomagnetic activity on Earth. Recent studies, however, have shown that solar wind dynamic pressure variations also cause global effects when they encounter the terrestrial magnetosphere. In particular, it has been shown that solar wind dynamic pressure enhancements significantly increase particle precipitation and cause global intensification of the aurora. Further studies using Defense Meteorological Satellite Program (DMSP) measurements have demonstrated that solar wind pressure increases also significantly affect the size of the polar cap and the cross‐polar cap potential drop. This implies that the dynamic pressure has an important effect on the coupling efficiency between the solar wind and the Earth’s magnetosphere, which is in addition to that due to the IMF. It was previously suggested, on the basis of the DMSP data, that solar wind dynamic pressure enhancements induce enhanced magnetotail reconnection and magnetospheric convection. We now present Super Dual Auroral Radar Network (SuperDARN) observations for a number of events that demonstrate significantly enhanced ionospheric convection in the dayside ionosphere associated with the impact of solar wind pressure fronts. The enhanced convection extends to the vicinity of the expected location of the dayside separatrix, suggesting that the solar wind dynamic pressure strongly affects dayside reconnection as well as polar‐cap convection.
Correlation between lightning types
Authors: Lapp J. L. , Saylor J. R.
Published: June 2007

The spatial correlation of cloud‐to‐ground (CG), intra‐cloud (IC), and narrow‐bipolar event (NBE) lightning was investigated. Lightning data were collected for a two‐month period in Florida. Separate analyses were performed for lightning over land and lightning over water. Space‐time cells were defined, and lightning flash density was computed on each cell for the three lightning types. Correlation coefficients were computed for each of the three pairs of lightning types: CG‐IC, IC‐NBE, and CG‐NBE. The CG‐IC lightning pair was correlated most strongly. Best fit curves were also produced for each pair of lightning densities. These were second order polynomial fits in log space. These fits displayed curvature on log‐log axes, signifying that the relative fractions of lightning types vary with storm intensity. The land/water separation did not have a strong effect on the relationships.
Adaptation of baroreflex function to increased carotid artery stiffening in patients with transposition of great arteries
Authors: Pinter Alexandra , Laszlo Andrea , Mersich Beatrix , Kadar Krisztina , Kollai Mark
Published: June 2007

We have shown previously that TGA (transposition of great arteries) is associated with increased carotid artery stiffness. It has been established that stiffening of the barosensory vessel wall results in reduced baroreceptor activation and impaired BRS (baroreflex sensitivity). In the present study we tested the hypothesis that the increased carotid artery stiffness in TGA patients was associated with reduced cardiovagal BRS. We studied 32 TGA patients aged 9–19 years, 12±3 years after surgical repair and 32 age-matched healthy control subjects. Carotid artery diastolic diameter and pulsatile distension was determined by echo wall tracking; carotid blood pressure was measured by tonometry. BRS was measured using spontaneous techniques [BRSseq and LFgain (low-frequency transfer function gain)] and by the phenylephrine method (BRSphe). Carotid artery distensibility was markedly reduced in patients as compared with controls (5.6±1.9×10−3 compared with 8.7±2.7×10−3/mmHg P<0.05, as determined using an unpaired Student's t test), but BRS was not different in patients and controls (20.3±14.7 compared with 21.7±12.7 for BRSseq; 13.1±9.2 compared with 10.6±4.5 for LFgain; and 19.1±8.6 compared with 24.8±7.2 for BRSphe respectively). Carotid artery elastic function was markedly impaired in patients with TGA, but the increased stiffness of the barosensory vessel wall was not associated with reduced BRS. It appears that attenuation of baroreceptor stimulus due to arterial stiffening may be compensated by other, possibly neural, mechanisms when it exists as a congenital abnormality.
Evaluation of ischaemia-modified albumin as a marker of myocardial ischaemia in end-stage renal disease
Authors: Sharma Rajan , Gaze David C. , Pellerin Denis , Mehta Rajnikant L. , Gregson Helen , Streather Christopher P. , Collinson Paul O. , Brecker Stephen J. D.
Published: June 2007

The early diagnosis of myocardial ischaemia is problematic in patients with ESRD (end-stage renal disease). The aim of the present study was to determine whether IMA (ischaemia-modified albumin) increases during dobutamine stress and detects myocardial ischaemia in patients with ESRD. A total of 114 renal transplant candidates were studied prospectively, and all received DSE (dobutamine stress echocardiography). IMA levels were taken at baseline and 1 h after cessation of DSE. A total of 35 patients (31%) had a positive DSE result. Baseline IMA levels were not significantly different in the DSE-positive and -negative groups. The increase in IMA was significantly higher in the DSE-positive group compared with those with no ischaemic response (26.5±19.1 compared with 8.2±9.6 kU/l respectively; P=0.007; where kU is kilo-units). From ROC (receiver operator charactertistic) curve analysis, the optimal IMA increase to predict an ischaemic response was 20 kU/l, with a sensitivity of 81% and a specificity of 72% [area under the curve, 0.80 (95% confidence interval, 0.44–0.94); P=0.03]. There were 18 deaths, ten of which were cardiac in nature over a follow up period of 2.25±0.71 years. An increase in IMA ≥20 kU/l was associated with significantly worse survival (P=0.02). In conclusion, IMA is a moderately accurate marker of myocardial ischaemia in ESRD. Patients with an increase in IMA ≥20 kU/l during DSE had significantly worse survival.
Spectral Data for Gallium: Ga I through Ga XXXI
Authors: Shirai T. , Reader J. , Kramida A. E. , Sugar J.
Published: June 2007

The energy levels and spectral lines of gallium atom in all stages of ionization have been compiled. Experimental data on spectral lines and energy levels exist for spectra Ga I through Ga VII, Ga XIII through Ga XXVI, and Ga XXX. For Li-like Ga XXIX through H-like Ga XXXI, theoretical data on energy levels and line wavelengths are compiled. For Ga I, Ga II, and Ga III we include radiative probabilities of electric-dipole transitions where available. For Ga XV through Ga XX, Ga XXIII through Ga XXVI, and Ga XXX, radiative probabilities of magnetic-dipole and electric-quadrupole transitions are included. The ground state configuration and term and a value of ionization energy are included for each ion.
Optical and electrical characterization of an atmospheric pressure microplasma jet for Ar∕CH4 and Ar∕C2H2 mixtures
Authors: Yanguas-Gil A. , Focke K. , Benedikt J. , von Keudell A.
Published: June 2007

A rf microplasma jet working at atmospheric pressure has been characterized for Ar, He, and Ar∕CH4 and Ar∕C2H2 mixtures. The microdischarge has a coaxial configuration, with a gap between the inner and outer electrodes of 250μm. The main flow runs through the gap of the coaxial structure, while the reactive gases are inserted through a capillary as inner electrode. The discharge is excited using a rf of 13.56MHz, and rms voltages around 200–250V and rms currents of 0.4–0.6A are obtained. Electron densities around 8×1020m−3 and gas temperatures lower than 400K have been measured using optical emission spectroscopy for main flows of 3slm and inner capillary flows of 160SCCM. By adjusting the flows, the flow pattern prevents the mixing of the reactive species with the ambient air in the discharge region, so that no traces of air are found even when the microplasma is operated in an open atmosphere. This is shown in Ar∕CH4 and Ar∕C2H2 plasmas, where no CO and CN species are present and the optical emission spectroscopy spectra are mainly dominated by CH and C2 bands. The ratio of these two species follows different trends with the amount of precursor for Ar∕CH4 and Ar∕C2H2 mixtures, showing the presence of distinct chemistries in each of them. In Ar∕C2H2 plasmas, CHx species are produced mainly by electron impact dissociation of C2H2 molecules, and the CHx∕C2Hx ratio is independent of the precursor amount. In Ar∕CH4 mixtures, C2Hx species are formed mainly by recombination of CHx species through three-body reactions, so that the CHx∕C2Hx ratio depends on the amount of CH4 present in the mixture. All these properties make our microplasma design of great interest for applications such as thin film growth or surface treatment.
A Fundamental Equation of State for Sulfur Hexafluoride (SF6) in Extended Equation of State Format
Authors: Scalabrin Giancarlo , Bettio Luigi , Marchi Paolo , Stringari Paolo
Published: June 2007

An innovative method for the regression of thermodynamic properties of pure fluids was recently proposed. The technique, indicated as an extended equation of state, adopts a framework similar to the extended corresponding states method, but a cubic equation is assumed instead of the equation of state of the reference fluid and the shape functions are expressed through a multilayer feedforward neural network. The use of a neural network assures a very high flexibility of the functional form to be regressed, so the resulting model reaches a representation accuracy which is comparable to that attained by the state-of-the-art multiparameter equations of state in the representation of the thermodynamic properties of a pure fluid. The technique was applied here to sulfur hexafluoride aiming at drawing its dedicated equation of state in a heuristic mode directly from the available experimental data. For sulfur hexafluoride (critical point is at Tc=318.7232K and Pc=3.754983MPa), experimental data of several properties in homogeneous states and of properties at phase equilibrium are available. The data approximately cover the range from the triple-point temperature at 223.6upto625K and for pressures up to 60MPa. The regression procedure was developed on a subset of well distributed density and vapor–liquid coexistence data, the so-called “training set,” and the model was successively validated for all the data sets, including the literature sources reporting values of isobaric heat capacity, speed of sound, and Joule–Thomson coefficient. The obtained results are satisfactory; in fact the proposed equation of state represents the available data within their experimental accuracy.
Atomic Weights of the Elements 2005
Authors: Wieser M. E.
Published: June 2007

The latest evaluation of atomic weight determinations and other cognate data has warranted 16 changes for the standard atomic weights of the elements, Ar(E), from those published previously in the Table of Atomic Weights 2001. The revised standard atomic weight are as follows: Ar(Al)=26.9815386(8), Ar(Bi)=208.98040(1), Ar(Cs)=132.9054519(2), Ar(Co)=58.933195(5), Ar(Au)=196.966569(4), Ar(La)=138.90547(7), Ar(Mn)=54.938045(5), Ar(Nd)=144.242(3), Ar(P)=30.973762(2), Ar(Pt)=195.084(9), Ar(Sm)=150.36(2), Ar(Sc)=44.955912(6), Ar(Na)=22.98976928(2), Ar(Ta)=180.94788(2), Ar(Tb)=158.92535(2), Ar(Th)=232.03806(2). A recommendation is made that δ13C values of all carbon-bearing materials be measured and expressed relative to Vienna-Pee Dee Belemnite on a scale normalized by assigning consensus values of −46.6‰ to L-SVEC lithium carbonate and +1.95‰ to NBS 19 calcium carbonate.
Application of dressing method for long wave–short wave resonance interaction equation
Authors: Yurova Maria
Published: June 2007

In this paper we investigate the application of the Zakharov-Shabat dressing method [Funct. Anal. Appl. 8, 226 (1974)] to (2+1)-dimensional long wave–short wave resonance interaction equation (LSRI). Using this method, we can construct the exact N-soliton solution of this equation depending on arbitrary constants. It contains both solutions which do not decay along N different directions in space infinity and “dromion” ones or localized solutions that decay exponentially in all directions.
Polarizable and flexible model for ethanol
Authors: Wang Shihao , Cann N. M.
Published: June 2007

A polarizable, flexible model for ethanol is obtained based on an extensive series of B3LYP∕6-311++G(d,p) calculations and molecular dynamics simulations. The ethanol model includes electric-field dependence in both the atomic charges and the intramolecular degrees of freedom. Field-dependent intramolecular potentials have been attempted only once previously, for OH and HH stretches in water [P. Cicu et al., J. Chem. Phys. 112, 8267 (2000)]. The torsional potential involving the hydrogen-bonding hydrogen in ethanol is found to be particularly field sensitive. The methodology for developing field-dependent potentials can be readily generalized to other molecules and is discussed in detail. Molecular dynamics simulations of bulk ethanol are performed and the results are assessed based on comparisons with the self-diffusion coefficient [N. Karger et al., J. Chem. Phys. 93, 3437 (1990)], dielectric constant [J. T. Kindt and C. A. Schmuttenmaer, J. Phys. Chem. 100, 10373 (1996)], enthalpy of vaporization [R. C. Wilhoit and B. J. Zwolinski, J. Phys. Chem. Ref. Data, Suppl. 2, 2 (1973)], and experimental interatomic distributions [C. J. Benmore and Y. L. Loh, J. Chem. Phys. 112, 5877 (2000)]. The simultaneous variation of the atomic charges and the intramolecular potentials requires modified equations of motion and a multiple time step algorithm has been implemented to solve these equations. The article concludes with a discussion of the bulk structure and properties with an emphasis on the hydrogen bonding network.
Inner and outer scalings in rough surface zero pressure gradient turbulent boundary layers
Authors: Brzek Brian , Cal Raúl Bayoán , Johansson Gunnar , Castillo Luciano
Published: June 2007

A new set of experiments have been performed in order to study the effects of surface roughness and Reynolds number on a zero pressure gradient turbulent boundary layer. In order to properly capture the x dependence of the single point statistics, consecutive measurements of 11 streamwise locations were performed which enabled the use of the full boundary layer equations to calculate the skin friction. This quantity was obtained within 3% and 5% accuracy for smooth and rough surfaces, respectively. For the sand grain type roughnesses used, only the Zagarola and Smits scaling, U∞δ*∕δ, was able to remove the effects of roughness and Reynolds number from the velocity profiles in outer variables. However, each scaling used for the velocity deficit profiles resulted in self-similar solutions for fixed experimental conditions. When examining the Reynolds stresses in the inner region [i.e., 0<(y+ϵ)+<0.1δ+], the ⟨u2⟩ component showed the largest influence of roughness, where the high peak near the wall was decreased and became nearly flat for the fully rough regime profiles. In addition, the Reynolds stresses in outer variables showed self-similarity for fixed experimental conditions. However, as the roughness parameter, k+ increases, all Reynolds stress profiles became similar in shape indicating increased isotropy near the wall. Furthermore, the boundary layer parameters also showed a considerable increase due to roughness.