bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permafrost distribution and active‐layer depths in the McMurdo Dry Valleys, Antarctica
Authors: Bockheim James G. , Campbell Iain B. , McLeod Malcolm 
Published: June 2007

AbstractThe McMurdo Dry Valleys (MDVs) constitute the largest ice‐free area (6700 km2) in Antarctica. Permafrost is ubiquitous in the region and is present as ground ice or buried ice, ice‐cemented permafrost and dry‐frozen permafrost. Using a combined dataset that includes more than 800 shallow (<1.5 m) excavations, we provide a map at a scale of 1:2 million showing the distribution of permafrost in the MDVs. Our data suggest that about 55% of the permafrost is ice cemented, 43% is dry frozen and ground/buried ice comprises at least 2% of the area. Permafrost form is related to climatic zone, age of sediments and local site factors. Ice is present in ice‐cored alpine moraines and coastal tills of Holocene age in hummocky drifts of late Quaternary age (ca. <115 ka); however, it is also present in Miocene‐aged sublimation till in Beacon Valley. Ice‐cemented permafrost is present not only in coastal areas (subxerous climatic zone) and in sediments of late Quaternary age, but also in soils of pre‐Quaternary‐age in ultraxerous regions along the polar plateau. Dry‐frozen permafrost exists along the floors and lower sidewalls of larger ice‐free valleys (xerous climatic zone) in sediments of pre‐late Quaternary age. Dry‐frozen permafrost, which may be unique to Antarctica, appears to form from sublimation of moisture in ice‐cemented permafrost over time. Active‐layer depths are 45 to 70 cm in coastal areas and in the eastern half of Wright and Taylor Valleys, 20 to 45 cm in other ice‐free areas within 60 km of McMurdo Sound, and <20 cm along the polar plateau. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of docking programs for predicting binding of Golgi α‐mannosidase II inhibitors: A comparison with crystallography
Authors: Englebienne Pablo , Fiaux Hélène , Kuntz Douglas A. , Corbeil Christopher R. , Gerber‐Lemaire Sandrine , Rose David R. , Moitessier Nicolas 
Published: June 2007

AbstractGolgi α‐mannosidase II (GMII), a zinc‐dependent glycosyl hydrolase, is a promising target for drug development in anti‐tumor therapies. Using X‐ray crystallography, we have determined the structure of Drosophila melanogaster GMII (dGMII) complexed with three different inhibitors exhibiting IC50's ranging from 80 to 1000 μM. These structures, along with those of seven other available dGMII/inhibitor complexes, were then used as a basis for the evaluation of seven docking programs (GOLD, Glide, FlexX, AutoDock, eHiTS, LigandFit, and FITTED). We found that small inhibitors could be accurately docked by most of the software, while docking of larger compounds (i.e., those with extended aromatic cycles or long aliphatic chains) was more problematic. Overall, Glide provided the best docking results, with the most accurately predicted binding around the active site zinc atom. Further evaluation of Glide's performance revealed its ability to extract active compounds from a benchmark library of decoys. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Distributed basis sets of s‐type Gaussian functions for simple diatomics: Anharmonic‐model distribution
Authors: Glushkov V. N. , Wilson S. 
Published: June 2007

AbstractAn anharmonic model for systematically distributing Gaussian basis sets is presented. Illustrative calculations demonstrate the new approach for the H, HeH2+ and H2 diatomic systems. The total ground state energies for the one‐electron systems and the ground state Hartree‐Fock energy for the H2 molecule supported by distributed basis sets constructed by means of the anharmonic model are compared with the corresponding energies obtained by invoking the variation principle to determine optimal exponents and positions. The use of a series of anharmonic distributions of s‐type Gaussian functions centred on regularly spaced points is also investigated. Calculated energy expectation values supported by our largest distributed basis sets differ from the corresponding exact values by 0.70 μHartree for the H ion and by 0.89 μHartree for the HeH2+ ion. For the ground state Hartree‐Fock energy of the H2 molecule, our distributed basis set yields a value which differs from the finite difference Hartree‐Fock value by 0.67 μHartree. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Andronov‐Hopf‐Bifurkation im Falle stetiger Parameterabhängigkeit
Authors: Schneider K. R. 
Published: June 2007

AbstractWir betrachten das Problem der Abzweigung einer periodischen Lösung von einer Gleichgewichtslösung eines zweidimensionalen autonomen Differentialgleichungssystems dx/dt = f(x, λ), falls λ einen kritischen Wert λ0 durchläuft. Unter den Voraussetzungen, daß f bezüglich x dreimal stetig differenzierbar ist, von λ aber nur stetig abhängt und daß beim Durchgang von λ durch λ0 nicht mehr als ein Grenzzyklus von der betrachteten stationären Lösung abzweigt (generischer Fall, der durch ein Koeffizientenkriterium charakterisiert wird), leiten wir ein Kriterium über die Bifurkationsrichtung ab, das diejenigen Kriterien verallgemeinert, die auf der Differenzierbarkeit von f bezüglich λ. basieren. Das Resultat ist auch auf n‐dimensionale Systeme anwendbar, die sich mittels einer Zentrumsmannigfaltigkeit auf zweidimensionale Systeme reduzieren lassen.
On Non‐Isothermal Rigid Shell Theory
Authors: Epstein M. , Glockner P. G. 
Published: June 2007

AbstractUsing the two fundamental laws of Thermodynamics, results are derived for placing restrictions on constitutive equations of rigid shells. This is achieved by dividing the shell into a number of fictitious layers and accommodating an arbitrary temperature field by use of a continuous piecewise linear coldness function across the thickness. Layer entropy densities are introduced in terms of which the entropy inequality is globally valid for each layer.
Zweiphasen‐Kontinuumstheorie einer Suspension starrer, Kugelförmiger Teilchen unter Berücksichtigung der Teilchenrotation
Authors: Immich H. 
Published: June 2007

AbstractFür eine Suspension starrer, kugelförmiger Teilchen in einem viskosen Fluid wird eine Zweiphasen‐Kontinuumstheorie (Zwei‐Fluid‐Modell) durch Anwenden einer Volumenmittelung hergeleitet. Es wird gezeigt, daß die volumengemittelten Spannungstensoren der kontinuierlichen und der dispersen Phase nicht symmetrisch sind, wenn man die Rotationsträgheit der starren Teilchen und das Wechselwirkungsmoment zwischen den Phasen berücksichtigt. Außerdem treten als Folge der Mittelung Momentenspannungen in der dispersen Phase auf. Teil I enthält die Ausgangsgleichungen und das Verfahren der Volumenmittelung.
Zur Berechnung von Überschreitenswahrscheinlichkeiten stochastisch beanspruchter mechanischer Systeme
Authors: Friedrich H. , Hennig K. 
Published: June 2007

AbstractBei der Untersuchung der Zuverlässigkeit und Sicherheit von stochastisch beanspruchten Konstruktionen besteht eine wesentliche Aufgabe in der Vorausbestimmung der Wahrscheinlichkeit dafür, daß ein solches System versagt, wenn die Beanspruchung oder ein anderer betrachteter stochastischer Prozeß in einem vorgegebenen Zeitintervall mindestens einmal ein bestimmtes Niveau überschreitet. Für diese Überschreitenswahrscheinlichkeit werden Berechnungsformeln abgeleitet.
A Branch and Bound Algorithm for a Transportation Type Problem with Piecewise Linear Convex Objective Function
Authors: Seshan C. R. , Achary K. K. 
Published: June 2007

AbstractA branch and bound type algorithm is presented in this paper to the problem of finding a transportation schedule which minimises the total transportation cost, where the transportation cost over each route is assumed to be a piecewice linear continuous convex function with increasing slopes. The algorithm is an extension of the work done by Balachandran and Perry, in which the transportation cost over each route is assumed to beapiecewise linear discontinuous function with decreasing slopes. A numerical example is solved illustrating the algorithm.
Topologische Matrizen in den Gleichungen diskreter, ebener, dehnsteifer Schwinger
Authors: Schade D. 
Published: June 2007

AbstractBeim automatisierten Aufstellen von Schwingungsgleichungen in vier verschiedenen Einflußzahlen muß der topologische Zusammenhang des Netzes des Schwingers beschrieben werden. In die Gleichungen mit Krafteinflußzahlen (Weggrößenverfahren) und mit Dehnungseinflußzahlen gehen Knotenmatrizen ein. Die Verschiebungseinflußzahlen (Kraftgrößenverfahren) enthalten Baum‐ und Maschenmatrizen. Die Gleichungen mit Schnittkrafteinflußzahlen sind Summengleichungen und lassen sich nur im Sonderfall mit Baum‐ und Maschenmatrix deuten.
Indentation of an Elastic Half‐Space by a Concave Rigid Punch
Authors: Shibuya Toshikazu 
Published: June 2007

AbstractIn this paper, the author analyzes exactly the stress state of an elastic half‐space indented by an axisymmetric concave rigid punch when the indented load is small and the contact area is an annulus. Numerical examples are presented for parabolic and conical concave punches.
Swirling Flow in a Straight Circular Pipe
Authors: Singh M. P. , Sinha P. C. , Aggarwal M. 
Published: June 2007

AbstractIn this paper the laminar axisymmetric swirling flow of an incompressible viscous fluid from the entry to the fully developed downstream region in a straight circular pipe of uniform cross‐section has been studied. The swirl has been prescribed at the entry, along with the longitudinal flow. The development of the flow has been divided into three regions and the analysis is based on the method of matched asymptotic expansions.
Zur numerischen Behandlung grenzflächendynamischer Probleme mittels Projektions‐Iterationsverfahren
Authors: Wilke H. 
Published: June 2007

AbstractDas Problem der Marangoni‐Instabilität führt auf eine nichtlineare Anfangs‐Randwertaufgabe. Ein Teilproblem für die Strömungsgeschwindigkeiten wird mit Hilfe eines Projektions‐Iterationsverfahrens numerisch gelöst. Ein Vergleich der benötigten Rechenzeiten zeigt gegenüber dem Differenzenverfahren ganz erstaunliche Vorteile der neuen numerischen Methode, so daß ihre Anwendung auf kompliziertere Probleme dieser Art sinnvoll erscheint.
Notwendige Optimalitätsbedingungen für Prozesse mit zeitvariablen Integralgleichungen in Banach‐Räumen
Authors: Schmidt W. H. 
Published: June 2007

AbstractMit Hilfe eines abstrakten Modells von L. Bittner werden für Prozesse, die in Banach‐Räumen durch Volterrasche oder Fredholmsche Integralgleichungen beschrieben werden, notwendige Optimalitätsbedingungen hergeleitet. Berücksichtigt wird eine Parameteroptimierung. Um Maximumprinzipien zu formulieren, nutzen wir die quellenmäßige Darstellung der Lösung einer Integralgleichung aus. Erörtert werden Existenz und Eigenschaften einer Resolvente für Integralgleichungen in Banach‐Räumen.
Schwingungen nichtmischbarer Flüssigkeiten im rotierenden Kreiszylinder
Authors: Bauer H. F. 
Published: June 2007

AbstractZur Auslegung eines Nutationsdämpfers für einen drallstabilisierten Satelliten muß das Verhalten eines Flüssigkeitssystems, bestehend aus zwei inkompressiblen, reibungsfreien und nichtmischbaren Flüssigkeiten in einem unendlich langen um seine Längsachse rotierenden Kreiszylinder untersucht werden. Dabei werden für den vollkommen gefüllten wie auch den teilweise gefüllten Behälter die natürlichen Frequenzen und die Flüssigkeitskräfte, Oberflächen‐ und Trennflächenauslenkung für Translations‐ und Rotationsanregung bestimmt.
MHD Flow in Finned Conducting Ducts
Authors: Ariel P. D. , Aggarwala B. D. 
Published: June 2007

AbstractIn the present paper investigation is made of magnetohydrodynamic flow of electrically conducting fluid through conducting rectangular ducts with internal fins from the walls which are perpendicular to the magnetic field. An analytical treatment is given to the solution which reduces to the solution of a Fredholm integral equation of second kind. Numerical results are provided for pressure drop parameter for varying fin‐length and Hartmann number and for different aspect ratios of the duct. It is found that the pressure drop parameter increases with an increase in either the fin‐length or the Hartmann number.
On Stokes Flow between Parallel Plates with Stationary Random Surface Roughness
Authors: Phan‐Thien N. 
Published: June 2007

AbstractThe problems of Stokes flow of an incompressible Newtonian fluid between corrugated plates are considered. The corrugations are of small amplitude ϵ and are represented by stationary random functions. An exact solution (up to O(ϵ2)) is developed leading to an expression for the pressure drop enhancement as a function of the statistics of the corrugations. Simplifications of this expression in the case of sinuisoidal and slowly‐varying corrugations are discussed.
Precise Analysis of Elastic‐Plastic Deformation of Thin‐Walled Cylindrical Shell with Clamped Ends under Internal Pressure
Authors: Ohashi Y. , Okouchi T. 
Published: June 2007

AbstractElastic‐plastic deformation of a thin‐walled cylindrical shell with clamped ends under internal pressure is analyzed using Hencky's theory together with Mises' yield criterion.
Profit Optimization in A Two‐Unit Maintained Standby Redundant System
Authors: Kumar A. , Lal R. 
Published: June 2007

AbstractThe paper deals with a 2‐unit cold standby redundant system with exponential failure‐time and general repair‐time distributions. Profit equations for the system have been developed under the most generalized cost structure in which the earning rate of the system in a state depends upon three parameters–‐present state, future state of visit and time at which the earning rate is measured. Laplace transforms of the profit that the system will earn in a given time when the discounting rate is exponential, are obtained. Limiting behaviour of the profit has also been discussed. Further, profit has been suggested as the measure of system's effectiveness. When different alternatives are available to a decision maker in each state to operate the system, an optimization problem to determine an optimal operating policy for the system which maximizes long term profit has been formulated. Howard's policy iteration method is used to develop an algorithm to determine an optimal policy for the system.
Über eine Kombinationsresonanz im Dreikörperproblem
Authors: Mettler E. 
Published: June 2007

AbstractDie vorliegende Arbeit befaßt sich mit der engen Verwandtschaft zwischen gewissen Teilen der Himmelsmechanik und der Schwingungslehre. Sie zeigt, daß die seit fast zwei Jahrhunderten bekannten säkularen Störungen im planetaren Dreikörperproblem eine Kombinationsresonanz mit Differenzfrequenz im Sinne der modernen Schwingungslehre darstellen.
Ein Variationskonzept zur Reduktion statischer Stabilitätsprobleme
Authors: Ruge P. 
Published: June 2007

AbstractIm Rahmen der Näherungsberechnung von statischen Stabilitätslasten λ Für kontinuierliche Systeme wird gezeigt, wie die Ordnung der finiten Übersetzung Ax = λBx reduziert werden kann. Die Methode beruht auf der Einführung von Versatzmomenten infolge der Spannungen im Grundzustand als unabhängiger Zustandsgröße neben der Durchsenkung. Dieses Variationskonzept erlaubt eine exakte statische Kondensation durch Elimination der Weggrößenparameter.
Application of Invariant Variational Principles to the Optimal Design of a Column
Authors: Komkov V. 
Published: June 2007

AbstractUsing Noether's technique we derive some invariants associated with the problems of optimization of design. While specifically a beam design problem is discussed here, the technique can be generalized in an obvious manner to thin plate, or shell problems. The specific problem discussed in this paper concerns the optimization of a column. Some invariants derived here as examples of the technique can be used to point out the basic difficulties discovered by much harder arguments in many recent papers. In particular, our method points out the existence of singularities which are associated with an optimal column design even in the absence of multiple eigenvalues in the Euler's eigenvalue problem, which corresponds to the buckling phenomenon.
On the Fibre Pull‐out Problem
Authors: Phan‐Thien N. , Goh C. J. 
Published: June 2007

AbstractIn this paper, the force required to pull out a long, slender fibre embedded in a semi‐infinite elastic matrix by a distance W is derived. Assuming that the fibre is slender and that there is no slip at the fibre‐matrix interface, it is shown that the nature of the inclusion depends on the parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{E^* }}{E}\left({\frac{R}{l}} \right)^2 \,\ln \,\left({\frac{{2l}}{R}} \right) $\end{document}, where E, E* are the Young's moduli of the matrix and the fibre respectively. R is a typical radius of the fibre and l its length. When this parameter is large, the fibre is effectively rigid and the load transfer occurs over the entire length of the fibre. If this parameter is very much less than unity, then the inclusion is elastic in nature and the load transfer occurs in a finite neighbourhood of the embedded end of the fibre which is near the free surface of the semi‐infinite matrix.
An Average Theory for the Dynamic Behavior of a Laminated Elastic‐Viscoplastic Work‐Hardening Medium
Authors: Aboudi J. , Benveniste Y. 
Published: June 2007

AbstractAn average theory which models the dynamic behavior of a bilaminated medium under specific types of loading, made of elastic viscoplastic work‐hardening materials is developed. Each constituent is represented by a unified theory of elastoviscoplasticity including work‐hardening, which requires neither a yield criterion nor loading or unloading conditions. The resulting effective theory appears in the form of a system of nonlinear differential equations for the avergage stresses, displacement and plastic work. The theory is applied to construct the effective stress‐strain curves of the laminated medium in which the transition from the elastic to the plastic domain can be determined. The theory is also applied to obtain the dynamic response of a laminated slab subjected to velocity or stress input.
Schätzung von Diskretisierungsfehlern bei der Lösung von Gleichungen in Banach‐Räumen
Authors: Lippold G. 
Published: June 2007

AbstractIn einer früheren Arbeit wurde eine Begründung der Schätzung von Diskretisierungsfehlern auf der Basis des Defektes in genaueren Gleichungen entwickelt, die sich ausschließlich am Stabilitätsbegriff für diskrete Abbildungsfolgen orientiert. Dieser Zugang wird hier so erweitert, daß er Aussagen zur Konsistenzordnung gestattet, die sonst über asymptotische Entwicklungen hergeleitet werden. Am Beispiel von Zweipunkt‐Randwertaufgaben für Systeme gewöhnlicher Differentialgleichungen wird die Tragfähigkeit der Ergebnisse demonstriert.
Optimalitätsbedingungen für Prozesse in Evolutionsgleichungen 1. Ordnung
Authors: Kampowsky W. 
Published: June 2007

AbstractDie Arbeit beschäftigt sich mit Problemen optimaler Steuerung, die durch nichtlineare Evolutionsgleichungen 1. Ordnung mit Anfangs‐ oder speziellen Randbedingungen beschrieben werden. Mit Hilfe eines abstrakten Modells von L. Bittner werden notwendige Optimalitätsbedingungen hergeleitet, die in einem Spezialfall auch hinreichend sind.
On the Theory of Diffusion Processes in Viscoelastic Media
Authors: Gröger K. , Hünlich R. 
Published: June 2007

AbstractThe paper deals with initial value problems describing diffusion processes in viscoelastic media. By means of the theory of maximal monotone operators in Hilbert spaces it is shown that these problems are uniquely solvable. Moreover, the convergence of an approximation method is proved.
Coulomb Friction in Two‐Dimensional Rigid Body Systems
Authors: Lötstedt P. 
Published: June 2007

AbstractDie Lösungen des Coulombschen Reibungsproblems für starre Körper in zwei Dimensionen werden analysiert. Das bestimmende System von gewöhnlichen Differentialgleichungen und Ungleichungen wird aufgestellt. Beispiele werden vorgelegt, die einige ungewünschte Eigenschaften dieses speziellen Reibungsgesetzes nachweisen. Hinreichende Bedingungen für Existenz und Eindeutigkeit werden mit Hilfe der Theorie der linearen Komplementarität hergeleitet.
Nicht‐lineare Schwingungen mit fast‐periodischer Parametererregung
Authors: Weidenhammer F. 
Published: June 2007

AbstractBekanntlich kann auch bei fast‐periodischer Parametererregung die Ruhelage für gewisse Frequenzen instabil werden. Die ersatzweise eintretenden nicht‐linearen Schwingungen werden näherungsweise für einige dieser Frequenzen berechnet.
On the Torsion of Elastic Cylindrical Bars
Authors: Bassali W. A. , Obaid S. A. 
Published: June 2007

AbstractCertain trigonometric formulae and combinatorial identities are used to derive exact and closed expressions for the stress functions, torsional rigidities and peripheral shearing stresses of certain isotropic cylinders under torsion. The cross sections are bounded by the closed curves \documentclass{article}\pagestyle{empty}\begin{document}$ r = a\left| {\sin \frac{\theta }{n}} \right|^n \left({ - \pi < \theta \mathbin{\lower.3ex\hbox{$\buildrel<\over {\smash{\scriptstyle=}\vphantom{_x}}$}} \pi } \right) $\end{document} where n is a positive integer (n > 1). Complex variable methods are applied to obtain the complex torsion functions, torsional rigidities and shearing stresses when the sections are bounded by the contours \documentclass{article}\pagestyle{empty}\begin{document}$ r = a\cos ^n \frac{\theta }{n}\left({ - \frac{{n\pi }}{2} < \theta \mathbin{\lower.3ex\hbox{$\buildrel<\over {\smash{\scriptstyle=}\vphantom{_x}}$}} \frac{{n\pi }}{2}} \right) $\end{document}, where n is a positive number (0 < n ≦ 2). Numerical results are presented in the form of tables and graphs illustrating the variation of torsional rigidities and the distribution of tangential shearing stresses along the edges of the cross sections. The cardioid and lemniscate of Bernoulli are included as special cases.
Re-envisioning the structure of last glacial vegetation in New Zealand using beetle fossils
Authors: Burge Philip I. , Shulmeister James 
Published: June 2007

AbstractA series of 18 fossil beetle assemblages are used to reconstruct the paleoenvironment of the northwest West Coast, New Zealand, over the period of the last interstadial–stadial transition (ca. 37,000–21,300 cal yr BP). The samples were recovered from an in-filled hollow within a dune field ca. 9 km south west of Westport (41°47′S, 171°30′E). This fossil beetle reconstruction is compared to an existing palynological reconstruction from the same site. The beetle assemblages indicate an environment of marshy shrubland interspersed with closed canopy coastal vegetation prior to glacial onset, and a mosaic of closed canopy patches and open tussock grassland during full glacial conditions. These interpretations, contrast with the palynologically based interpretation which indicates subalpine shrubland prior to glacial onset and widespread grassland with little woody vegetation during the period of maximum glacial cooling. This study is consistent with other non-pollen studies in New Zealand and indicates that the palynological interpretation of the paleoenvironment of the Westport region downplays the importance of closed canopy vegetation in the area during the transition from interstadial to full glacial (stadial) conditions. It challenges the interpretation of open vegetation at low elevations during glacial periods from pollen studies.