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  • 1
    Electronic Resource
    Electronic Resource
    Time-resolved investigations of sidewall recombination in dry-etched GaAs wires (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2016-2018 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the sidewall recombination in dry-etched GaAs/GaAlAs wires with widths between 12 μm and 300 nm using picosecond spectroscopy. The wires were fabricated with electron beam lithography and different reactive ion etching processes. The excitonic lifetimes decrease strongly with decreasing wire widths due to sidewall recombination. Using a model calculation to fit the experimentally observed width dependence of the lifetimes the surface recombination velocity is determined to be S=2×106 cm/s at 50 K. S increases with temperature and is independent of the etching process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103003
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Carrier capture in intermixed quantum wires with sharp lateral confinement (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 48-50 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated GaAs/GaAlAs quantum wires with widths between 220 and 40 nm by high-dose (2×1014 cm−2) Ga implantation in a locally masked single quantum well structure. The width dependence of the emission energies indicates a steep 1D confinement determined by the lateral straggling of the implanted Ga. The external quantum efficiency of the wires increases strongly with decreasing mask width due to significant carrier capture from the lateral barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102643
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  • 3
    Electronic Resource
    Electronic Resource
    Carrier transport into intermixed GaAs/AlGaAs quantum wires (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1256-1258 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have realized GaAs/AlGaAs quantum wires using the implantation induced intermixing technique. The transport of carriers from the AlGaAs barriers into the intermixed quantum well (QW) is studied by comparing low temperature photoluminescence spectra at resonant and nonresonant excitation. It is shown that hardly any carriers generated in the AlGaAs are captured in the intermixed QW. At resonant excitation a large lateral diffusion length of carriers from the lateral barriers into the wires is observed which is reduced at higher temperatures due to implantation defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108751
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Diffusion of Silver Nitrate in Concentrated Aqueous Solutions (1966)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 70 (1966), S. 536-539 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100874a036
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  • 5
    Electronic Resource
    Electronic Resource
    Safe bounds for the solutions of nonlinear problems using a parallel multisplitting method (1989)
    Springer
    Computing 42 (1989), S. 171-186 
    Details
    ISSN: 1436-5057
    Keywords: 65G10 ; 65H10 ; 65W05 ; CR: G. 1.0 ; G.1.5 ; Parallel methods ; nonlinear systems ; enclosures ; error bounds ; interval iterative methods ; multisplittings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Für gewisse Systeme nichtlinearer GleichungenF(x)=0 entwicklen wir ein Verfahren, welches iterativ enge untere und obere Schranken für die Nullstellen vonF berechnet. Das Verfahren beruht auf einem Multisplitting für bestimmte Matrizen und weist so in natürlcher Weise Parallelität auf. Wir geben Kriterien für die Konvergenz der Schranken gegen die Nullstellen an und untersuchen die Konvergenzgeschwindigkeit.
    Notes: Abstract For some systems of nonlinear equationsF(x)=0 we derive an algorithm which iteratively constructs tight lower and upper bounds for the zeros ofF. The algorithm is based on a multisplitting of certain matrices thus showing a natural parallelism. We prove criteria for the convergence of the bounds towards the zeros and we investigate the speed of convergence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02239746
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  • 6
    Electronic Resource
    Electronic Resource
    Some remarks on two interval-arithmetic modifications of the newton method (1992)
    Springer
    Computing 48 (1992), S. 125-128 
    Details
    ISSN: 1436-5057
    Keywords: 65H10 ; 65G10 ; Nonlinear equations ; systems of nonlinear equations ; interval Newton method ; interval Gaussian algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit werden das Intervall-Newton-Verfahren und das vereinfachte Intervall-Newton-Verfahren betrachtet, um enge Schranken für die Lösungen nichtlinearer Gleichungssysteme zu erhalten. Unter starkem Bezug auf eine Arbeit von Alefeld über diese beiden Verfahren leiten wir einen Zusammenhang zwischen den beiden Matrizen her, die in der erwähnten Veröffentlichung bei der Formulierung hinreichender Konvergenzkriterien auftreten. Desweiteren beantworten wir eine dort gestellte Frage über den Abbruch der Verfahren nach endlich vielen Schritten.
    Notes: Abstract In this paper we consider the interval Newton method and its simplified version to find tight bounds for the solutions of systems of nonlinear equations. Referring to a paper of Alefeld on this subject, we derive a connection between the two matrices used there to formulate sufficient criteria for the convergence of these methods. We also answer an open question concerning the break down of the Newton method after a finite number of steps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02241710
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  • 7
    Electronic Resource
    Electronic Resource
    Enclosing the solution set of linear systems with inaccurate data by iterative methods based on incomplete LU-decompositions (1985)
    Springer
    Computing 35 (1985), S. 189-206 
    Details
    ISSN: 1436-5057
    Keywords: 65F10 ; 65G10 ; Interval arithmetic ; linear systems of equations ; iterative solution methods ; incompleteLU-decompositions ; comparison theorems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Vorgestellt wird eine Klasse von Iterationsverfahren zur Einschließung der Lösungsmenge durch einen Intervallvektor; dabei ist einen×n Intervall-H-Matrix und ein Intervallvektor. Der betrachtete Algorithmus verallgemeinert ein Iterationsverfahren von Meijerink/van der Vorst, das auf einer unvollständigenLU-Zerlegung einerM-MatrixA basiert. Es werden Aussagen über die Durchführbarkeit des Algorithmus, seiner Konvergenzgeschwindigkeit und seiner Einschließungsgüte gemacht. Da das ursprüngliche Verfahren von Meijerink/van der Vorst ein Spezialfall des vorliegenden Algorithmus ist, erhält man damit gleichzeitig seine Durchführbarkeit in der größeren Klasse derH-Matrizen. Als weitere Anwendung auf reelle Matrizen erhält man einen Zusammenhang zwischen demR 1-Faktor (Ortega/Rheinboldt [9]) des ursprünglichen Verfahrens und der zugrundeliegenden IndexmengeP.
    Notes: Abstract We present a class of iterative methods to enclose the solution set by an interval vector;A is varying in ann×n intervalH-Matrix andb is varying in an interval vector . The algorithm taken into consideration generalizes an iterative method of Meijerink/van der Vorst based on an incompleteLU-decomposition of anM-MatrixA. Theorems concerning the feasibility of the algorithm, its rate of convergence and its quality of enclosure are given. Since the original method of Meijerink/van der Vorst is a special case of our algorithm we have thus shown its applicability to the larger class ofH-matrices. Furthermore we relate theR 1-factor (as defined in Ortega/Rheinboldt [9]) of the original method to the underlying setP of indices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260505
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  • 8
    Electronic Resource
    Electronic Resource
    Efficient methods for enclosing solutions of systems of nonlinear equations (1990)
    Springer
    Computing 44 (1990), S. 221-235 
    Details
    ISSN: 1436-5057
    Keywords: 65G10 ; 65H10 ; Newton's method ; Newton-Gauss-Seidel method ; nonlinear equations ; R-order ; interval analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten Modifikationen des Intervall-Newton-Verfahrens, welche zwei Ansätze miteinander verbinden: Mehrfache (z.B.s-fache) Verwendung derselben Auswertung der Jacobi-Matrix und näherungsweise Lösung der Newton-Gleichung mit einem „linearen” Iterationsprozeß. Insbesondere zeigen wir, daß dieR-Ordnung dieser Verfahrens+1 werden kann. Wir illustrieren unsere Ergebnisse an einem numerischen Beispiel.
    Notes: Abstract We consider modifications of the interval Newton method which combine two ideas: Reusing the same evaluation of the Jacobian several (says) times and approximately solving the Newton equation by some ‘linear’ iterative process. We show in particular that theR-order of these methods may becomes+1. We illustrate our results by a numerical example.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262218
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    On the theory and practice of multisplitting methods in parallel computation (1992)
    Springer
    Computing 49 (1992), S. 63-74 
    Details
    ISSN: 1436-5057
    Keywords: 65W05 ; 65F10 ; 65N20 ; Multisplittings ; parallel iterative methods ; SOR method ; local memory parallel computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir geben Konvergenz-und Vergleichsaussagen für parallele iterative Multisplitting-Verfahren mit verschiedenen Gewichtungsschemata. Insbesondere zeigen wir, daß bestimmte Gauss-Seidel Multisplitting-Verfahren nicht schneller konvergieren können als das gewöhnliche Gauss-Seidel-Verfahren. Wir berichten darüber hinaus über numerische Experimente auf einem 64-Prozessor-Rechner mit lokalem Speicher. Diese Experimente zeigen, daß der ‘naive’ Einsatz von Multisplittings leicht zu nicht zufriedenstellenden Ergebnissen führen kann, wenn mehr also nur ein paar Prozessoren eingesetzt werden.
    Notes: Abstract We present convergence and comparison theorems on parallel iterative multisplitting methods with different weighting schemes. In particular, we show that certain Gauss-Seidel multisplittings cannot converge faster than the usual Gauss-Seidel method. We also give numerical results on a 64 processor local memory computer. These experiments show that the ‘naive’ use of multisplittings can easily produce unsatisfactory results on parallel computers with more than just a few processors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02238650
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  • 10
    Electronic Resource
    Electronic Resource
    Plättchen-assoziierte Immunglobuline (PAIg) beim HELLP-Syndrom (1991)
    Springer
    Archives of gynecology and obstetrics 250 (1991), S. 695-704 
    Details
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02372894
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    Paper (German National Licenses)
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