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  • Articles: DFG German National Licenses  (49)
  • Chemistry  (43)
  • 15A48  (3)
  • 90C20  (3)
  • 1
    Electronic Resource
    Electronic Resource
    On theR-order of coupled sequences arising in single-step type methods (1988)
    Springer
    Numerische Mathematik 53 (1988), S. 653-661 
    Details
    ISSN: 0945-3245
    Keywords: AMS(MOS): 65H10 ; 15A48 ; CR: G1.5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary As shown in preceding papers of the authors, the verification of anR-convergence order τ for sequences coupled by a system (1.1) of basic inequalities can be reduced to the positive solvability of system (3.3) of linear inequalities. Further, the bestR-order $$\bar \tau$$ implied by (1.1) is equal to the minimal spectral radius of certain matrices composed from the exponents occuring in (1.1). Now, these results are proven in a unified and essentially simpler way. Moreover, they are somewhat extended in order to facilitate applications to concrete methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01397134
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Convexity preserving interpolation with exponential splines (1986)
    Springer
    Computing 36 (1986), S. 335-342 
    Details
    ISSN: 1436-5057
    Keywords: 65D07 ; 41A15 ; 90C20 ; Convexity conditions ; weakly coupled system of inequalities ; numerical algorithms ; quadratic programming ; unconstrained dual program with tridiagonal Hessian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Während die Aufgabe der konvexen Interpolation im Falle kubischer Splines im allgemeineen nicht lösbar ist, kann jetzt gezeigt werden, daß sie bei Verwendung von Exponentialsplines Lösungen besitzt sofern die vorkommenden Parameter hinreichend roß sind, und es werden konkrete hinreichende und notwendige Lösbarkeitsbedingungen hergeleitet. Da eindeutige Lösbarkeit in der Regel nicht vorliegt, wird eine Auswahlfunktion eingeführt und das entstehende quadratische Optimierungsproblem nach Dualisierung numerisch behandelt.
    Notes: Abstract Sufficient and necessary conditions are derived under which interpolating splines are convex if the data set is in convex position. In order to select one of the interpolants, by means of a well-known objective function a quadratic optimization problem is stated which can be solved effectively by passing to a dual program.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02240208
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  • 3
    Electronic Resource
    Electronic Resource
    On the R-order of coupled sequences III (1983)
    Springer
    Computing 30 (1983), S. 157-169 
    Details
    ISSN: 1436-5057
    Keywords: 65H10 ; 15A48 ; Iterative parallel processes ; best individualR-orders ; ordered positive decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Für konvergente Folgen {x n,1 },...,{x n,s }, welche über ein System (2) von Ungleichungen miteinander verkoppelt sind, werden die besten individuellenR-Ordnungen τ1,...,τ s bestimmt. Dazu wird gezeigt, daß diese gleich den Spektralradien von bestimmten Matrizen sind, welche aus Exponenten in (2) gebildet werden.
    Notes: Abstract For convergent sequences {x n,1 },...{x n,s } coupled by a system (2) of inequalities the optimal individualR-orders τ1,...,τ s are determined as the spectral radii of certain matrices composed of exponents appearing in (2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02280786
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of the cone radius for positive concave operators (1984)
    Springer
    Computing 33 (1984), S. 37-49 
    Details
    ISSN: 1436-5057
    Keywords: 65H10 ; 90C30 ; 15A48 ; Iterative processes ; bestR-orders ; cone radius of concave operators ; spectral radii ; partial ordering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die Berechnung der bestenR-Ordnung von Folgen aus iterativen Näherungsverfahren führt auf die Ermittlung des hier eingeführten Kegelradius bestimmter konkaver Operatoren. Das Hauptergebnis der Arbeit ist die Darstellung des Kegelradius als Infimum der Spektralradien aller den konkaven Operator majorisierenden linearen Operatoren. Diese Charakterisierung ist von numerischem Intersse.
    Notes: Abstract The computation of bestR-orders of sequences produced by iterative methods leads to the determination of the cone radius of certain concave operators. The main result of the paper is the representation of the cone radius as the infimum of spectral radii of all linear operators majorizing the concave operator. This characterization is of numerical interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02243074
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  • 5
    Electronic Resource
    Electronic Resource
    Convex spline interpolants with minimal curvature (1985)
    Springer
    Computing 35 (1985), S. 219-229 
    Details
    ISSN: 1436-5057
    Keywords: 65K05 ; 65D07 ; 90C20 ; 41A15 ; Existence conditions ; quadratic programming ; dual optimization problem ; tridiagonal Hessian ; Newton's method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Das Problem, konvexe Interpolationssplines mit minimaler mittlerer Krümmung zu ermitteln, führt auf eine speziell strukturierte quadratische Optimierungsaufgabe. In der vorliegenden Note wird eine zugehörige duale Aufgabe aufgestellt, die ohne Nebenbedingungen auskommt, deren Zielfunktion stückweise quadratisch ist und die daher eine effektive numerische Behandlung erlaubt.
    Notes: Abstract The problem of finding convex spline interpolants with minimal mean curvature leads to a quadratic optimization problem of special structure. In the present note a corresponding dual problem without constraints is derived. Its objective function is piecewise quadratic and therefore admits an effective numerical treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260507
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Lichen substances - 126Lichen Substances - 125: G. Follmann and S. Huneck, Nova Hedwigia Z. Kryptogamenkd. in press. mass spectroscopy of natural products - 10. Comparative positive and negative ion mass spectroscopy of usnic acid and related compounds (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1980), S. 301-308 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fragmentation behaviour of 16 selected usnic acid derivatives has been studied. A comparison of their positive (10-16 e V) and negative (2-4 e V) ion mass spectra showed differences not only in the fragmentation patterns but also in the mechanisms of some elimination reactions as established by deuterated analogues.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200070707
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  • 7
    Electronic Resource
    Electronic Resource
    Lichen substances - 128Part 127: E. G. Sundholm and S. Huneck, Chem. Scr. in press. Mass spectroscopy of natural products - 12Part 11: J. Schmidt, K. Seifert, S. Härtling, S. Johne and H. J. Veith, Biomed. Mass Spectrom. 8, 13 (1981).. Comparative positive and negative ion mass spectroscopy of nitrogen-containing and ring C cleaved usnic acid derivatives (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 293-300 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral fragmentation behaviour of some nitrogen-containing and ring C cleaved usnic acid derivatives has been studied. The principal fragmentation pathway is drastically changed in the nitrogen-containing compounds when compared to that observed with the ring C cleaved derivatives. The main fragment ions of the ring C derivatives are also present in the mass spectrum of usnic acid itself.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200080703
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  • 8
    Electronic Resource
    Electronic Resource
    Mass spectroscopy of natural products. XI - Mass spectroscopic investigations of N-6 substituted ergoline derivatives (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 13-18 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fragmentation behaviour of N-6 substituted ergoline derivatives (acylaminothiocarbonyl, thiazolyl) has been studied using electron impact, field desorption and collisional activation mass spectrometry. The specific fragmentations are compared with structurally related compounds (piperidine and piperidine-3-carboxylic acid methyl ester derivatives).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200080105
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  • 9
    Electronic Resource
    Electronic Resource
    Mass spectroscopy of natural products XXII - the negative ion mass spectra of brassinosteroidsFor part XXI see: M. H. A. Elgamal, D. Voigt and G. Adam, J. prakt, Chem., in press. (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 663-666 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The negative ion mass spectra of some brassinosteroids are discussed in comparison with their positive ones. In contrast to the EI-mass spectra the negative ion mass spectra show strong peaks in the molecular ion region. The nature of an intense [M - 4]-· ion was investigated on the base of model compounds and deuterium labeled derivatives.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200131205
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  • 10
    Electronic Resource
    Electronic Resource
    Use of adiabatic experiments for kinetic studies in fixed catalyst beds (1964)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 10 (1964), S. 149-154 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is presented for using an adiabatic reactor to study the kinetics of reactions of gases on solid catalysts. The method is based on measurement of the steady state axial profile of temperature or composition in a specially designed adiabatic packed bed reactor. Reaction rates are calculated from these measured profiles by graphical differentitation. The method is applicable for multireaction systems and for any type of kinetic behavior.The method was demonstrated by an experimental study of cumene cracking an silica-alumina catalyst at 420° to 480°C. The measured reaction rates are in satisfactory agreement with results obtained by other investigators who used isothermal reactors. Areas of application of the adiabatic method are suggested.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690100205
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