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 19 of 19 for “"Rheological models"”.
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Analysis of Discrete Fractional Operators and Discrete Fractional Rheological Models
… fractional operators and discrete fractional rheological constitutive equations. In the first part of the thesis, we introduce and prove new monotonicity concepts in discrete fractional calculus. In the remainder, we carry previous results about fractional rheological models to the discrete …
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Model selection in rheology: Providing a practical framework, surveying the field, and assessing the uses and limitations of BIC
The selection of which model or models to use when studying a complex fluid is of constant relevance in rheology, though often too little attention is paid to framing this problem of selection such as to yield consistent, credible, and meaningful results. In this thesis I provide a novel framework …
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On-line rheology, flow simulation and system-based modelling of twin-screw extrusion processing of corn meal
Rheological characterization of corn meal formulations was carried out using a twin screw extruder as a rheometer. On-line rheometrical techniques used for rheological characterization of non-food polymers were modified to make them adaptable to food materials extruded in a twin-screw extruder. The …
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Photoelastic study of dense granular free-surface flow rheology and size segregation
… analogies between discrete and continuous flow models and characterise force chain preferential orientations. Secondly, we interpret current rheological models in the context of our experimental system, and hence propose that non-local effects may in fact be dependent on the local force network …
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ΘΕΡΜΟΜΗΧΑΝΙΚΗ ΣΥΜΠΕΡΙΦΟΡΑ ΤΗΣ ΛΙΘΟΣΦΑΙΡΑΣ ΣΤΟΝ ΕΛΛΗΝΙΚΟ ΧΩΡΟ
… GEOPHYSICAL DATA RELATED TO THE CRUST STRUCTURE, RHEOLOGICAL MODELS FOR THE STRENGTH OF THE LITHOSPHERE. OFFSHORE AND WEST OF PARGA THE VERTICAL PRINCIPAL STRESS (ΣΝ) IS INTERMEDIATE BETWEEN ΣΗ AND ΣΗ, IN NW PELOPONNESE ΣΝ EXCEEDS ΣΗ WITH A SLIGHT DIFFERENCY ONLY, WHEREAS IT ISΣΝ>>ΣΗ>ΣΗ IN THE …
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Propagation of fluid driven fractures in transversely isotropic material
… behavior which can be reproduced by different rheological models with varying levels of accuracy (Carreau, power law, Ellis). In this thesis, we focus on hydraulic fractures in impermeable TI media. We assume that the fracture propagates normal to the isotropy plane without any further …
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Helical flow of non-Newtonian fluids, with reference to drilling fluid flow.
… of the flow and its complexities, mathematical models are considered, and a 'helical flow' model adopted as being a reasonable approximation to the flow which may be solved in practice. Rheological models for the fluids are discussed, and it is shown that, with helical flow, a shear rate …
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Numerical and field data analysis of drill stem vibration
… stem taking into account two different fluid rheological models. The obtained equation of motion was assembled using the finite element analysis which was solved numerically in Matlab®.</p> <p>The sensitivity analysis using Euler-Bernoulli and Timoshenko models, showed that the Euler-Bernoulli …
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Finite element simulation of viscoelastic flow: effect of the rheological model and the mesh
… differences that may be found by using several rheological models to describe the behaviour of the non-Newtonian fluids. The finite element simulation of viscoelastic fluid flows results in non-linear simultaneous equation systems that have to be solved iteratively. The iterations for all the …
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Bubble dynamics in polymeric foams
… or reaction injection moulding. We use standard rheological models (Oldroyd B and Pompom) to investigate bubble growth driven by gas diffusion as a model for injection moulding. To model reaction injection moulding, we develop a new fluid model based on existing linear theory for a gelling …
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On the Thermally Induced Failure of Rolling Element Bearings
… bearings is developed that can utilize different rheological models and traction curves in order to calculate the traction coefficient between the rollers and the raceways. The validity of this dynamic model is verified by comparing the simulation results with the previously published experimental …
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Understanding Structure-Property Relationships for Impact Polystyrene
… thereby follow morphology development. Ex situ rheological methods were then employed on post-phase inversion samples to extract interfacial tension using well-established quantitative rheological models. Polymerizations were conducted at 80 °C for 6 hours with 5 wt% total polybutadiene, …
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Two-Dimensional Transient Flows and Stability of Concentrated Suspensions of Clay Particles and Rheology
… are studied theoretically and experimentally. Rheological measurements using a state-of-the-art rheometer show that the shear history of concentrated suspensions of clay particles can be divided into three regions: solid-rigid, nearly Newtonian, and shear-thinning regions. The nearly Newtonian …
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Modelling dry granular flows over topography
… of grains, which flow like a liquid? Various rheological models of granular flows have been developed to facilitate a continuum approach, but hitherto they have only been applied to flows in very simple geometries such as parallel shear flow. In these applications, the flows are assumed to be …
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Prediction of Time-Dependent Stresses and Deflections in Prestressed, Concrete Girders: From Start of Fabrication to End of Service Life
… and numerous fabrication conditions. The current models used to predict the deflection history are largely empirical and, although they account approximately for some of the important effects, they do not explicitly consider the interactions among these factors. The goal of this research was to …
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GPS based analysis of earthquake induced phenomena at the Sunda Arc
… types of real-time sensor data with numerical models of earthquake sources and tsunami propagation. This thesis was created as a result of the GITEWS project (German Indonesian Tsunami Early Warning System). It is based on five research papers and manuscripts. Main project-related task was the …
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The linear and nonlinear rheology of multiscale complex fluids
… fluids have remained elusive. Moreover, the rheological behavior of these materials under extensional deformations, which is important in applications such as spraying and fiber spinning, is relatively poorly understood. The primary contribution of this thesis is the development of a compact …
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Viscoelastic and fracture behaviour of polyolefin based nanocomposites
… in the molten state was studied through dynamic rheological tests. It was evidenced how the introduction of fumed silica nanoparticles and precipitated silica microparticles could lead very strong enhancement both of the storage (Gâ€TM) and shear moduli (Gâ€TMâ€TM), and of the viscosity (η), …
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Micro- and macro-rheological studies of the structure and association dynamics of biopolymer gels
… In this thesis, we use a combination of rheological testing and constitutive modeling to study this relationship between microstructure and mechanical properties in three biologically-relevant complex fluid systems. First, we explore the network structure and association dynamics of …