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A comprehensive mathematical model of the hot extrusion process for aluminum alloys has been developed and validated. The model is capable of predicting the material flow behaviour and microstructure evolution that occurs in aluminum alloy AA3003 during extrusion. The plasticity module was developed using a commercial finite element package, DEFORM, a transient Lagrangian model which couples the thermal and deformation phenomena and is able to predict the temperature, strain rate and strain distribution in the billet/extrudate at any position in the container and die. Validation of the model against industrial data indicated that it gave excellent predictions of the pressure and temperature history during extrusion. Material flow effects during extrusion such as surface cladding (a transverse weld defect) as one billet is fed in after another through the die were also well predicted. The results of the FEM model for material flow and thermomechanical history were post processed using MATLAB software to predict the grain deformation and stored energy in the extruded material as well as the thickness and extent of the transverse weld defect. Finally, the model predictions for microstructure and transverse weld were compared to microstructure observations. The stored energy or driving pressure for Static Recrystallization (SRX) and Geometric Dynamic Recrystallization (GDRX) and how they are influenced by extrusion parameters were investigated using the mathematical model and experimental measurements. The experimental measurements for grain thickness and microstructural features made using Electron Back Scattered Diffraction (EBSD) technique and optical microscope show good agreement with model predictions. The mathematical model was then used to assess the effect a change in die design would have on the flow behaviour of the material during extrusion and on the transverse weld that forms.

The purpose of this study is to develop, evaluate, and apply a CRISSP-2D river ice model for a highly complex reach of the Nelson River upstream of the Jenpeg Generating Station in northern Manitoba. The calibrated model is applied in a backcasting scenario to evaluate its potential of predicting the river ice regime associated with specific hydraulic and meteorologic conditions. Secondly, a real-time application is conducted in collaboration with Manitoba Hydro to forecast overnight ice conditions as part of the 2011 Ice Stabilization Program. The model is shown to be fully capable of predicting the onset and type of ice regime that occurs. Spatial variation in ice generation across the study region is accurately captured, including locations of thermal bridging and initial ice front advance. Several modelling limitations associated with parameterization limit model accuracy during the latter stages of freeze-up and are identified as enhancement opportunities.

Modern and future many-core systems represent large and complex architectures. The communication fabrics in these large systems play an important role in their performance and power consumption. Current simulation methodologies for evaluating networks-on-chip (NoCs) are not keeping pace with the increased complexity of our systems; architects often want to explore many different design knobs quickly. Methodologies that trade-off some accuracy but maintain important workload trends for faster simulation times are highly beneficial at early stages of architectural exploration. We propose a synthetic traffic generation methodology that captures both application behaviour and cache coherence traffic to rapidly evaluate NoCs. This allows designers to quickly indulge in detailed performance simulations without the cost of long-running full system simulation but still capture a full range of application and coherence behaviour. Our methodology has an average (geometric) error of 10.9% relative to full system simulation, and provides 50x speedup on average over full system simulation.

The catastrophic consequences associated with landslides necessitate predictions of these hazards to be made with as much certainty as possible. However, the often complex nature of these events make predictions highly challenging. In this thesis, a number of hypotheses related to the triggering mechanisms and subsequent consequences of landslides in a loose-granular soil were investigated. The investigation was conducted using small-scale geotechnical centrifuge models, and a new flume facility developed to examine landslide behavior in a reduced-scale model. The first hypothesis explored in this research was that static liquefaction might preferentially occur in the saturated granular soil located at the base of the landslide rather than the well-drained inclined portion of the slope. Using a geotechnical centrifuge model, it was found that a small initial toe failure did act as a monotonic loading trigger to shear the loose contractile saturated sand at the base of the slope and caused liquefaction to occur. The second hypothesis investigated whether the consequences of a landslide triggered under elevated groundwater antecedent conditions are higher than scenarios under drier antecedent conditions. Results from five centrifuge models subjected to different antecedent groundwater conditions show that higher groundwater conditions can result in landslides with velocities about three times higher and travel distances eight times higher than low antecedent conditions. The third hypothesis investigated the influence of slope inclination on landslide consequences. Seven geotechnical centrifuge models were built and tested, comparing the consequences of landslides triggered in 20° and 30° sloped models with different groundwater conditions. The results of these tests found that the influence of slope angle on the mobility consequences of a triggered landslide are highly dependent on the antecedent groundwater conditions. The most significant case was under high groundwater conditions, where the shallower 20° slope travelled twice the distance and speed of the steeper 30° slope. A new flume facility was developed to examine landslide behaviour in a reduced-scale model, and a direct comparison was made to one of the centrifuge models from the research. The comparison demonstrated the challenges associated with using reduced-scale models to study suction-dominated problems such as hydraulically-induced landslides in loose granular soils. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2014-04-29 16:45:11.335

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The objective of this study is to examine the thermo-mechanical evolution of the Yorkshire(Cleveland), Sole Pit and East Midland Basins, Southern North Sea using theoretical models of basin formation(subsidence) and basin destruction(inversion).Subsidence occurs in response to a driving tectonic force and is amplified by the input of sediments, which impart a load on the Uthosphere. The form of subsidence varies depending on the degree of crustal and sub-crustal involvement. In order to isolate this driving tectonic subsidence the loading effect of the sediments is removed by backstripping. Intrinsic to the accurate modelling of basin formation using this method are firstly, the presence of a complete sedimentary sequence representing the maximum load on the basement and secondly, a normal and representative compaction trend. Subsidence in the Yorkshire, Sole Pit and East Midland Basins was terminated in the late Cretaceous-early Tertiary by inversion. This inversion is demonstrated to have been controlled by pre-existing structures and accommodated differentially within the Yorkshire and Sole Pit Basins in the form of basement uplift and shortening. A significant proportion of the sediments was removed by this uplift. This is quantified by studying compaction trends and is used to reconstruct the basin configuration prior to inversion to facilitate modelling of basin formation. The patterns of subsidence appear to conform well to those predicted by a model of simple lithospheric stretching with a rapid initial subsidence followed by more gentle thermal and flexural subsidence. Superimposed on this background subsidence are discrete events which appear to be related to periods of active faulting or increases in regional loading(eustatic). Subsidence, like inversion, occurs differentially within the fault bounded margins of the Yorkshire and Sole Pit Basins. The relationship between faults at different crustal levels is complicated by stress partitioning by Permo-Triassic salt horizons, yet it does appear that reactivation of Carboniferous and older structures has influenced the geological evolution of these basins.

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Modern building design is complex and involves many different disciplines operating in a fragmented manner. Appropriate computer-based decision support (DS) tools are sought that can raise the level of integration of different activities at the conceptual stage, in order to help create better designs solutions. This project investigates opportunities that exist for using techniques based upon the Genetic Algorithm (GA) to support critical activities of conceptual building design (CBD). Collective independent studies have shown that the GA is a powerful optimisation and exploratory search technique with widespread application. The GA is essentially very simple yet it offers robustness and domain independence. The GA efficiently searches a domain to exploit highly suitable information. It maintains multiple solutions to problems simultaneously and is well suited to non-linear problems and those of a discontinuous nature found in engineering design. The literature search first examines traditional approaches to supporting conceptual design. Existing GA techniques and applications are discussed which include pioneering studies in the field of detailed structural design. Broader GA studies are also reported which have demonstrated possibilities for investigating geometrical, topological and member size variation. The tasks and goals of conceptual design are studied. A rationale is introduced, aimed at enabling the GA to be applied in a manner that provides the most effective support to the designer. Numerical experiments with floor planning are presented. These studies provide a basic foundation for a subsequent design support system (OSS) capable ofgenerating structural design concepts. A hierarchical Structured GA (SGA) created by Oasgupta et al [1] is investigated to support the generation of diverse structural design concepts. The SGA supports variation in the size, shape and structural configuration of a building and in the choice of structural frame type and floor system. The benefits and limitations of the SGA approach are discussed. The creation of a prototype DSS system, abritrarily called Designer-Pro (OPRO), is described. A detailed building design model is introduced which is required for design development and appraisal. Simplifications, design rationale and generic component modelling are mentioned. A cost-based single criteria optimisation problem (SCOP) is created in which other constraints are represented as design parameters. The thesis describes the importance of the object-oriented programming (OOP) paradigm for creating a versatile design model and the need for complementary graphical user interface (Gill) tools to provide human-computer interaction (HCI) capabilities for control and intelligent design manipulation. Techniques that increase flexibility in the generation and appraisal of concept are presented. Tools presented include a convergence plot of design solutions that supports cursor-interrogation to reveal the details of individual concepts. The graph permits study of design progression, or evolution of optimum design solutions. A visualisation tool is also presented. The DPRO system supports multiple operating modes, including single-design appraisal and enumerative search (ES). Case study examples are provided which demonstrate the applicability of the DPRO system to a range of different design scenarios. The DPRO system performs well in all tests. A parametric study demonstrates the potential of the system for DS. Limitations of the current approach and opportunities to broaden the study form part of the scope for further work. Some suggestions for further study are made, based upon newly-emerging techniques.