Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 15 of 15 for “"relaxation spectra"”.
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Developments in 2D NMR relaxometry and its application to biological tissue
… lamb’s liver and kidney. A novel use of 2D T1-T2 relaxation spectra to provide characteristic profiles of specific tissues in specific states of health is proposed and tested in the case of osteoarthritis using human articular knee cartilage obtained from the Norfolk and Norwich University …
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A study of internal friction in a high chromium-high nickel stainless steel
Relaxation spectra were determined for a high chromium-high nickel vacuum cast stainless steel. The specimens were tested in the following three conditions: (1) as-received and solution heat treated, (2) nitrided 20 hours and solution heat treated, and (3) nitrided 40 hours and solution heat …
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Direct Computations of Spatially Resolved Viscoelastic Moduli of Biomolecular Condensates
… modulus, loss modulus, crossover frequency, and relaxation time spectra. Our results reveal a strong correlation between topological features and mechanical response, with the condensate interior exhibiting higher stiffness and faster relaxation than the interface. The relaxation spectra provide …
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Analyses and predictions of ultrasound interactions with model biomembrane systems via two-state transition model
… employed to investigate biomembrane structural relaxation kinetics via absorption and velocity dispersion spectroscopy. The multilamellar vesicles utilized in this investigation were either composed of pure phospholipids or mixtures of phospholipids and small molar fractions of protein …
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Aspects of ultrasonic relaxation spectrometry
… a new method forthe analysis of the ultrasonic relaxation spectra of molecules undergoing conformational changes.The analytical technique described has the advantageover previous methods of treating ultrasonic relaxation dataon conformational systems, in that for the first time, enthalpy …
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An ultrasonic study of trapped hydrogen tunneling systems in Nb and Ta
… data on H and D tunneling systems. The observed relaxation rate of H in Ta was found to be consistent with an electronic mechanism for the relaxation. The most significant result found was that driving the Nb host into the normal state reduces the energy splitting of the iv tunneling systems as …
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Design tools for linear viscoelastic fluids
… design. We make extensive use of the continuous relaxation spectra description of the material response $H(\tau)$ an important design-appropriate material description to define low-dimensional material descriptions. We use these material descriptions to build cross-property Ashby-style diagrams …
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Optical study of shear and longitudinal acoustic waves and complex relaxation dynamics of glass forming liquids
… refined and used to study the complex structural relaxation dynamics of glass forming liquids, allowing both empirical modeling and testing of the predictions of the mode-coupling theory (MCT). Longitudinal and shear acoustic waves throughout much of the MHz frequency range, time-dependent thermal …
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Modeling of the linear viscoelastic response of polymer modified asphalt binders at intermediate and high temperatures
… on the behavior of dynamic master curves and relaxation spectra were studied. Feasibility of using the current mathematical models of frequency dependence to characterize the experimental dynamic master curves of modified binders was investigated. These models were generally found inadequate …
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Theory of the general orientation dependence of ²H NMR spin-lattice relaxation and experiments on model membranes
… nuclear magnetic resonance (NMR) spin-lattice relaxation was used to explore molecular motions. A general theory of relaxation rates was developed. Motions fast on the NMR timescale were investigated, model-independently, in the acyl chain and headgroup of phospholipids in the liquid …
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Ultrafast photo-acoustic spectroscopy of super-cooled liquids
… the study of supercooled liquids whose slower relaxation dynamics extend to gigahertz frequencies at high temperatures and whose faster dynamics are centered uniquely in the gigahertz frequency range. The experimental approach used a unique laser pulse shaping technique and, in the case of …
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Methods for the integrated design of viscoelastic materials and structural geometry
… with complex behavior (e.g., viscoelastic stress relaxation) are generally more expensive to solve. However, the computational cost of numerical models is a crucial factor in the success of integrated and multidisciplinary design optimization. Not all models are design-appropriate. Specifically, …
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Charakterisierung von Elastomeren mittels dynamischer Indentation und vergleichender Methoden
… tip and sample below Tg. Evaluation of the relaxation spectra revealed, that for successful dynamic indentation the condition (f = frequency, = main relaxation time) has to be fulfilled. Indentation experiments below the glass transition temperature show, that the shape of the indentation …
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Relaxation von Polymeren unter räumlichen Einschränkungen
… des dynamischen Spektrums. Das entstehende <br>Relaxationsspektrum weist, analog zur freien Kette, ein Maximum <br>auf, welches aber um einen Faktor von ca. 2.5 verschoben ist. Dieses Ergebnis <br>befindet sich in Übereinstimmung mit experimentellen Resultaten der <br>dielektrischen Relaxation. …
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Novel Rheometric Techniques and Constitutive Models for Linear and Nonlinear Rheology: Applications to Polymeric Solutions and Colloidal Gels
… history can be challenging due to their broad relaxation spectrum and time-varying (or “mutating”) material response. Part I of this thesis therefore deals with developing constitutive models relevant for polymeric solutions that exhibit broad viscoelastic relaxation spectra, and mutating …