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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 1073-1080 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Diaminopropanes exhibit strong elimination of amines from the molecular ions upon electron-impact. This is followed by secondary reactions in the course of which a substituent from the C-2 of the propane unit is eliminated and also a N-substituent to a smaller degree. Lowering the electron density at only one nitrogen atom by appropriate substituents causes a decrease in the intensity of both [M-amine]+· ions. The corresponding fragmentation processes were investigated by means of deuterium labelling.
    Notes: 1,3-Diaminopropane spalten beim Elektronestoßinduzierten Zerfall in starkem Maße aus den Molekülionen Amine ab. Dem schließen sich Folgereaktionen an, in deren Verlauf Vorzugsweise ein Substituent vom C-2 der Propankette, in geringerem Maße jedoch auch ein N-Substituent eliminiert werden. Erniedrigung der Elektronendichte an nur einem Stickstoffaton durch geeignete Substituenten führt Zu einem Intensitätsabfall beider [M-Amin]+· Ionen. Die zugrun-deliegenden Fragmentierungsprozesse wurden mit Hilfe deuterierter Verbindungen untersucht.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-07-13
    Description: Prognostics of large composite structures is a topic of increasing interest in the field of structural health monitoring for aerospace, civil, and mechanical systems. Along with recent advancements in real-time structural health data acquisition and processing for damage detection and characterization, model-based stochastic methods for life prediction are showing promising results in the literature. Among various model-based approaches, particle-filtering algorithms are particularly capable in coping with uncertainties associated with the process. These include uncertainties about information on the damage extent and the inherent uncertainties of the damage propagation process. Some efforts have shown successful applications of particle filtering-based frameworks for predicting the matrix crack evolution and structural stiffness degradation caused by repetitive fatigue loads. Effects of other damage modes such as delamination, however, are not incorporated in these works. It is well established that delamination and matrix cracks not only co-exist in most laminate structures during the fatigue degradation process but also affect each other's progression. Furthermore, delamination significantly alters the stress-state in the laminates and accelerates the material degradation leading to catastrophic failure. Therefore, the work presented herein proposes a particle filtering-based framework for predicting a structure's remaining useful life with consideration of multiple co-existing damage-mechanisms. The framework uses an energy-based model from the composite modeling literature. The multiple damage-mode model has been shown to suitably estimate the energy release rate of cross-ply laminates as affected by matrix cracks and delamination modes. The model is also able to estimate the reduction in stiffness of the damaged laminate. This information is then used in the algorithms for life prediction capabilities. First, a brief summary of the energy-based damage model is provided. Then, the paper describes how the model is embedded within the prognostic framework and how the prognostics performance is assessed using observations from run-to-failure experiments
    Keywords: Composite Materials
    Type: ARC-E-DAA-TN31177 , European Conference on Structural Control (EACS 2016); Jul 11, 2016 - Jul 13, 2016; Sheffield; United Kingdom
    Format: application/pdf
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