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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Manuscripta mathematica 28 (1979), S. 317-336 
    ISSN: 1432-1785
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract It is a well known theorem for Sturmian boundary value problems Lx=r Rx=0 that the pair (L, R=0) is inverse monotone (i. e. Lx ≧0, Rx=0 ⇒ x≧0) if there exists a weak majorizing element, i. e. a function z≧0 satisfying Lz≧0, Rz=0. We show that this criterion carries over to ordinary boundary value problems of arbitrary order if in addition there exists an inverse monotone pair ‘larger” than (L, R) in a certain sense. This follows from a variant of Schröder's theorem [10] combined with a result on strict monotonicity of nonnegative Green's functions. However, it will also be shown that the additional condition can only be dispensed with, if the boundary value problem is at most of the second order. Furthermore an analogous result holds, for elliptic boundary value problems in arbitrary dimensions.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Numerische Mathematik 29 (1978), S. 209-226 
    ISSN: 0945-3245
    Schlagwort(e): AMS(MOS): 65L 10 ; CR: 5.17
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Summary In this paper we give a simple stability theory for finite difference approximations to linear ordinary boundary value problems. In particular we consider stability with respect to a maximum norm including all difference quotients up to the order of the differential equation. It is shown that stability in this sense holds if and only if the principal part of the differential equation is discretized in a “stable way”. This last property is characterized by root conditions which we prove to be satisfied for some classes of finite difference schemes. Our approach simplifies and generalizes some known results of the literature where Sobolev norms or merely the maximum norm are used.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Numerische Mathematik 80 (1998), S. 1-38 
    ISSN: 0945-3245
    Schlagwort(e): Mathematics Subject Classification (1991): 34C35, 58F14, 65F50, 65H17
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Summary. In this paper we develop a numerical method for computing higher order local approximations of invariant manifolds, such as stable, unstable or center manifolds near steady states of a dynamical system. The underlying system is assumed to be large in the sense that a large sparse Jacobian at the equilibrium occurs, for which only a linear (black box) solver and a low dimensional invariant subspace is available, but for which methods like the QR–Algorithm are considered to be too expensive. Our method is based on an analysis of the multilinear Sylvester equations for the higher derivatives which can be solved under certain nonresonance conditions. These conditions are weaker than the standard gap conditions on the spectrum which guarantee the existence of the invariant manifold. The final algorithm requires the solution of several large linear systems with a bordered Jacobian. To these systems we apply a block elimination method recently developed by Govaerts and Pryce [12, 14].
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Numerische Mathematik 51 (1987), S. 103-122 
    ISSN: 0945-3245
    Schlagwort(e): AMS(MOS) 65L05, 58F08, 58F22 ; CR: G1.7
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Summary We show that a one-step method as applied to a dynamical system with a hyperbolic periodic orbit, exhibits an invariant closed curve for sufficiently small step size. This invariant curve converges to the periodic orbit with the order of the method and it inherits the stability of the periodic orbit. The dynamics of the one-step method on the invariant curve can be described by the rotation number for which we derive an asymptotic expression. Our results complement those of [2, 3] where one-step methods were shown to create invariant curves if the dynamical system has a periodic orbit which is stable in either time direction or if the system undergoes a Hopf bifurcation.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    The @journal of organic chemistry 46 (1981), S. 5119-5124 
    ISSN: 1520-6904
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3752-3756 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this article, a new curve of the correction factor for the measurement of sheet resistance of a square sample with a square four-point probe is presented by using the theory of conformal transformation. This curve is quite different from that obtained by using the theory of infinite dipoles. An experimental curve is recommended to use. The function of the conformal transformation used in this article is simple and can be easily used for solving the problem of boundary effect of current field. The theoretical curve is suitable to the boundary areas of wafers.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3757-3762 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: By using conformal transformation to take account of the boundary effect, it has been confirmed that there are some areas of a square sample near the corners besides the boundary suitable to the resistance measurement of Van der Pauw's method. The theoretical criterion of the suitability is whether Van der Pauw's formula for calculation of the sheet resistance is still valid provided the voltage values in the formula for two times the measurement are substituted with those obtained by using the theory of conformal transformation. The experimental criterion is whether the experimental values of sheet resistance for probes in some areas are equal to that for them at the boundary for the same sample. The experimentally confirmed areas are larger than what the theory predicts. Our repeated experiments show that the areas out of the circle tangent to the boundary are suitable to Van der Pauw's method.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3983-3986 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The X-band electron-spin-resonance spectra of Fe-doped [Ca,Y](Ti,Al)O3 perovskite single crystals show five resonant lines. Two of the five lines have an inverse phase in the first-derivative curve. The possibility of emission transition of a paramagnetic ion in an anisotropic environment and/or in the presence of oscillating distortions is discussed in this paper.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Cambridge : Cambridge University Press
    Ageing and society 3 (1983), S. 23-42 
    ISSN: 0144-686X
    Quelle: Cambridge Journals Digital Archives
    Thema: Medizin , Sociologie
    Notizen: The analysis of modern-age stratification systems must be based on the social organisation of work. This requires a theoretical approach that takes into account the structure of economic production, but also the fact that work is a meaningful activity of human beings within their life-world. The task therefore consists of integrating ‘materialist’ and ‘interpretive’ approaches to social reality. This integration is attempted in an examination of the special problems encountered by workers in the second half of their work life, as created by the ‘construction of ageing’ in the industrial firm. Existing approaches drawn from industrial sociology, stress structural features of the production process, whilst labelling theory stresses culturally induced age labels. Both are one-sided. A more comprehensive approach has to conceptualise the industrial firm as an actor with strategies based on economic rationality and as a life-world constituted by what is taken for granted by its members. The final section applies this framework to an empirical case study.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    European food research and technology 135 (1967), S. 135-140 
    ISSN: 1438-2385
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Zusammenfassung Für die Bestimmung des monomeren Acrylnitrils und Styrols einzeln und nebeneinander in Styrolpolymerisaten wurde eine besonders einfache Apparatur zur Isolierung der Monomeren aus den flüchtigen Bestandteilen entwickelt. Die in Dimethylformamid absorbierten monomeren Verbindungen werden nach Zusatz des Leitelektrolyten polarographisch bestimmt. Die Nachweisempfindlichkeit des polarographischen Verfahrens liegt bei 2 μg Acrylnitril bzw. 4 μg Styrol/ml Mcßlösung. Die Methode wird zur schnellen and einfachen Prüfung von Polystyrol und Polystyrol-Mischpolymerisaten als Bedarfsgegenstände im Sinne des Lebensmittelgesetzes vorgeschlagen und ermöglicht mit Sicherheit, Acrylnitril und Styrol in Plasten in Konzentrationen bis zu 0,01 % herab zu bestimmen.
    Materialart: Digitale Medien
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