Cancer is a complex, multi-scale disease marked by unchecked cellular growth and proliferation. As a tumor grows, it is known to lose its capacity to maintain a compact structure. This stage of development, known as invasion, is marked by the disaggregation and dispersion of peripheral cells, and the formation of finger-like margins. This thesis provides an overview of three multi-scale models of tumor growth and invasion. The hybrid discrete-continuum (HDC) model couples a cellular automaton approach, which is used to direct the behavior and interactions of individual cells, with a system of reaction-diffusion-chemotaxis equations that describe the micro-environment. The evolutionary hybrid cellular automaton (EHCA) model maintains the core of the HDC approach, but employs an artificial response network to describe cellular dynamics. In contrast to these two, the immersed boundary (IBCell) model describes cells as fully deformable, viscoelastic entities that interact with each other using membrane bound receptors. As part of this thesis, the HDC model has been modified to examine the role of the ECM as a barrier to cellular expansion. The results of these simulations will be presented and discussed in the context of tumor progression.

Cancer is a complex, multi-scale disease marked by unchecked cellular growth and proliferation. As a tumor grows, it is known to lose its capacity to maintain a compact structure. This stage of development, known as invasion, is marked by the disaggregation and dispersion of peripheral cells, and the formation of finger-like margins. This thesis provides an overview of three multi-scale models of tumor growth and invasion. The hybrid discrete-continuum (HDC) model couples a cellular automaton approach, which is used to direct the behavior and interactions of individual cells, with a system of reaction-diffusion-chemotaxis equations that describe the micro-environment. The evolutionary hybrid cellular automaton (EHCA) model maintains the core of the HDC approach, but employs an artificial response network to describe cellular dynamics. In contrast to these two, the immersed boundary (IBCell) model describes cells as fully deformable, viscoelastic entities that interact with each other using membrane bound receptors. As part of this thesis, the HDC model has been modified to examine the role of the ECM as a barrier to cellular expansion. The results of these simulations will be presented and discussed in the context of tumor progression.

In seismic field operations complex problems often arise which cannot be solved mathematically. In recent years investigators in both the commercial and academic fields have begun to approach the problems of elastic wave propagation by the use of seismic scale models. This thesis discusses the results measured from simulated seismic activity on a scale model built by the researcher.

In order to establish the rules and criteria· to be satisfied in order to develop a scale model, which may be employed to predict the dynamic behaviour of a fullscale rope-guide mineshaft installation, the theory of the dynamic behaviour of rope-guides is considered. In order to establish to what degree a scale model rope-guide system may be expected to simulate the dynamic behaviour of its fullscale prototype a series of correlation test on an existing rope-guide installation and its dynamic scale model are described. A further series of model investigations into the aerodynamic scale effects which may occur in rope-guide installations, are also described. These investigations demonstrate certain limitations in the use of dynamic scale models of rope-guides and also explain the mechanism of air flow in shaftscontaining bluff bodies. On the strength of the experience gained in this research recommendations are made for the execution of efficient experimental investigations into the dynamic behaviour of various rope-guide mineshaft installations. 6ome information is also provided on the actual design of fullscale rope-guide systems. / Thesis (PhD)--University of Pretoria, 1965. / gm2014 / Mechanical and Aeronautical Engineering / unrestricted

During the teeming process of molten steel from a ladle, a bathtub-type vortex may be formed in the ladle. The vortex entrains undesired slag on the surface into the tundish, lowering the quality. The formation of such vortices has been studied using two different scale models. Since the kinematic viscosity of water is similar to that of molten steel, the molten steel was simulated by water in the experiments. The Particle Image Velocimetry (PIV) technique was used to measure water flow patterns. Results show that the initial tangential velocity of water is responsible for the vortex formation. The effects of Reynolds and Froude numbers on the vortex formation were investigated and Froude number was found to be the dominant pi-number. A Computational Fluid Dynamics (CFD) modeling was also conducted to simulate the vortex formation with good agreement with the experiments.

This thesis is an architectural study surveying on miniature parks and miniature models exhibited in them and particularly focuses on Miniaturk - the first miniature park of Turkey- located in Istanbul. It is established as an environment containing a group of miniature models of buildings and landscapes, which display the variety, and richness of the cultural tradition of the previous and contemporary Anatolian civilizations, and especially Ottoman grandeur. In this study, it is argued that Miniaturk stands as a hybrid category between a museum, a public park and entertainment centre. Miniaturk is also conceived as an architectural environment providing a possible ground to discuss the conceptions, misconceptions and presuppositions about architecture in the popular realm and in the professional and disciplinary framework. Thereby, Miniaturk is investigated through the processes of its production including the initial design idea and all the stages of its construction. This study also tries to discuss the miniature models from different points of view. Whether they are considered as tools of architectural representation or not by the professionals, the popularity and the communicative advantage of these models can be used to arouse interest in the cultural and historical heritage as well as the contemporary architecture. The daily life of man on the street is strictly connected with architecture / therefore Miniaturk requires recognition as an environment for realization of these connections and relations.

Multi-scale modelling and analysis is becoming increasingly important and relevant. Analysis of the emergent properties from the interactions between scales of multi-scale systems is important to aid in solutions. There is no universally adopted theoretical/computational framework or language for the construction of multi-scale models. Most modelling approaches are specific to the problem that they are addressing and use a hybrid combination of modelling languages to model specific scales. This thesis addresses if process algebra can offer a unique opportunity in the definition and analysis of multi-scale models. In this thesis the generic Process Algebra with Layers (PAL) is defined: a language for multi-scale integration modelling. This work highlights the potential of process algebra to model multi-scale systems. PAL was designed based on features and challenges found from modelling a multi-scale system in an existing process algebra. The unique features of PAL are the layers: Population and Organism. The novel language modularises the spatial scales of the system into layers, therefore, modularising the detail of each scale. An Organism can represent a molecule, organelle, cell, tissue, organ or any organism. An Organism is described by internal species. An internal species, dependent on the scale of the Organism, can also represent a molecule, organelle, cell, tissue, organ or any organism. Populations hold specific types of Organism, for example, life stages, cell phases, infectious states and many more. The Population and Organism layers are integrated through mirrored actions. This novel language allows the clear definition of scales and interactions within and between these scales in one model. PAL can be applied to define a variety of multi-scale systems. PAL has been applied to two unrelated multi-scale system case studies to highlight the advantages of the generic novel language. Firstly the effects of ocean acidification on the life stages of the Pacific oyster. Secondly the effects of DNA damage from cancer treatment on the length of a cell cycle and cell population growth.

Evolutionary game theory has recently emerged as a key paradigm in various behavioral science disciplines. In particular it provides powerful tools and a conceptual framework for the analysis of the time evolution of strategic interdependence among players and its consequences, especially when the players are spatially distributed and linked in a complex social network. We develop various evolutionary game models, analyze these models using appropriate techniques, and study their applications to complex phenomena. In the second chapter, we derive integro-differential equations as deterministic approximations of the microscopic updating stochastic processes. These generalize the known mean-field ordinary differential equations and provide powerful tools to investigate the spatial effects on the time evolutions of the agents' strategy choices. The deterministic equations allow us to identify many interesting features of the evolution of strategy profiles in a population, such as standing and traveling waves, and pattern formation, especially in replicator-type evolutions. We introduce several methods of decomposition of two player normal form games in the third chapter. Viewing the set of all games as a vector space, we exhibit explicit orthonormal bases for the subspaces of potential games, zero-sum games, and their orthogonal complements which we call anti-potential games and anti-zero-sum games, respectively. Perhaps surprisingly, every anti-potential game comes either from Rock-paper-scissors type games (in the case of symmetric games) or from Matching Pennies type games (in the case of asymmetric games). Using these decompositions, we prove old (and some new) cycle criteria for potential and zero-sum games (as orthogonality relations between subspaces). We illustrate the usefulness of our decompositions by (a) analyzing the generalized Rock-Paper-Scissors game, (b) completely characterizing the set of all null-stable games, (c) providing a large class of strict stable games, (d) relating the game decomposition to the Hodge decomposition of vector fields for the replicator equations, (e) constructing Lyapunov functions for some replicator dynamics, (f) constructing Zeeman games -games with an interior asymptotically stable Nash equilibrium and a pure strategy ESS. The hierarchical modeling of evolutionary games provides flexibility in addressing the complex nature of social interactions as well as systematic frameworks in which one can keep track of the interplay of within-group dynamics and between-group competitions. For example, it can model husbands and wives' interactions, playing an asymmetric game with each other, while engaging coordination problems with the likes in other families. In the fourth chapter, we provide hierarchical stochastic models of evolutionary games and approximations of these processes, and study their applications

The study examines the issue of scale regarding models when analyzing daylight, which scale is the most representative of a real space. There have been previous studies done regarding scale model and daylight, however, they do not look at how the scale itself can affect the experience of daylight. The use of the architects’ already built scale model can be seen as valuable for light designers when evaluations and visualizing daylight in a real space. However, the use of the architect's scale model depends on its scale, hence why this study is being conducted. The aim of this study is to evaluate the effects the scale has on daylight visualization with scale models. This study began with conducting a small literature study regarding daylight, scale models, visual perception and practical consideration when using scale models. The method was designed thereafter. By choosing a real room to base the scale models on, three scales were chosen, 1:50, 1:20 and 1:10. Thereafter the questionnaire was designed by using the analyzing method PERCIFAL as a base. The result of the study showed the subject's answers regarding; light level, shadows, light distribution and specular reflections. As well as a question regarding which scale model the found most representative of the real room and why. The compiled data showed which scale model was the most representative of the real room. The results show a difference between the different scale models and a correlation to the real room is seen. In conclusion, the scale model can be used to estimate and visualize the daylight within a space. However, the scale must be regarded and looked at so the chosen scale can represent the real space, which allows for an easy view of the model.

Thesis (PhD)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The Square Kilometre Array (SKA) and its demonstrator MeerKAT are being designed to operate over a wide frequency range and are expected to achieve greater sensitivity and resolution than existing telescopes. The radio astronomy community is well aware of the negative impact that radio frequency interference (RFI) has on observations in the proposed frequency band. This is because weak radio signals such as those from pulsars and distant galaxies are difficult to detect on their own. The presence of RFI sources in the telescope’s operating area can severely corrupt observation data, leading to inaccurate or misleading results. Power-line interference and radiation from electric fences are examples of RFI sources. Mitigation techniques for these interference sources in the SKA system’s electromagnetic environment are essential to ensure the success of this project. These techniques can be achieved with appropriate understanding of the characteristics of the noise sources. Overhead power-line interference is known to be caused mainly by corona and gap-type (commonly known as sparking noise) discharges. Sparking noise is the dominant interference for the SKA. It is mainly encountered on wooden pole lines, which are usually distribution lines operated at up to 66 kV AC in the South African network. At this voltage level, the voltage gradients on the lines are insufficient to generate conductor corona. The power requirements for SKA precursors will be below this voltage level. The aim of the research in this dissertation is to evaluate the power line sparking characteristics through measurements and simulation of line radiation and propagation characteristics. An artificially made sparking noise generator, which is mounted on a power line, is used as noise source and the radiation characteristics are measured. Measurements were carried out in different environments, which included a high-voltage laboratory (HV-Lab), a 40m test-line, and another 22-kV test line of approximately 1.5 km. The key sparking noise parameters of interest were the temporal and spectral characteristics. The time domain features considered were the pulse shape and the repetition rate. The lateral, longitudinal and height attenuation profiles were also quantified. Since sparking noise current pulses are injected or induced onto power line conductors, the line will act as an unintentional antenna. The far-field radiation characteristics of the line were evaluated through measurements on physical scale-model structures and simulations. 1/120th and 1/200th scaled lines, using an absorbing material and metallic ground planes, respectively, were simulated in FEKO. The measurements of the constructed scale models were taken in the anechoic chamber. Both measurements and simulations showed that the line exhibits an end-fire antenna pattern mode. Line length, pulse injection point and line configuration were some of the parameters found to affect the radiation patterns. The findings from this study are used to determine techniques to identify the sparking noise, and locate and correct the sources when they occur on the line hardware. Appropriate equipment is recommended to be used for the location and correction of sparking noise. / AFRIKAANSE OPSOMMING: Die Vierkante Kilometer Reeks (SKA) en sy demonstrasie projek, die Karoo Reeks Teleskoop (KAT), word ontwerp om oor 'n wye frekwensie-bereik te funksioneer. Beide sal na verwagting beter sensitiwiteit en resolusie as bestaande radioteleskope he. Die radio-astronomie-gemeenskap is deeglik bewus van die negatiewe impak wat radio-frekwensie steurnisse (RFS) op waarnemings in die voorgestelde frekwensieband het. Die rede hiervoor is dat swak radio-seine soos die van pulsars en verafgelee sterrestelsels inherent moeilik is om te bepaal. Die teenwoordigheid van RFS bronne in die teleskoop se onmiddellike operasionele gebied kan waarnemings nadelig beinvloed. Dit lei uiteindelik tot onakkurate of misleidende resultate. Kraglyne en uitstralings van elektriese heinings is voorbeelde van RFS bronne. Metodes om die oorsake van die steurnisse van die SKA se elektromagnetiese omgewing te verminder is noodsaaklik om die sukses van hierdie projekt te verseker. Dit vereis egter deeglike begrip van die eienskappe van hierdie bronne. Steurnisse as gevolg van oorhoofse kraglyne word hoofsaaklik veroorsaak deur korona en gapingtipe ontladings (algemeen bekend as vonkontladings). Vonkontladings word hier beskou as die belangrikste oorsaak van steurnisse vir die SKA. Dit word in die Suid-Afrikaanse netwerk hoofsaaklik aangetref op houtpaal-installasies, wat gewoonlik bestaan uit distribusie lyne wat tot en met 66 kV wisselstroom (WS) bedryf word. By hierdie operasionele spanning is die spanningsgradient op die lyn onvoldoende om korona op te wek. Die kragvereistes vir die SKA se voorafgaande projekte sal sodanig wees dat hierdie spanningsvlak nie oorskry sal word nie. Die doel van die navorsing omskryf in hierdie proefskrif is om die eienskappe van vonkontladings rondom kraglyne te evalueer. Dit word gedoen met behulp van metings en simulasies van uitstralings- en voortplantingspatrone wat met 'n spesifieke lyn geassosieer kan word. 'n Kunsmatige vonkontladingsopwekker word op 'n kraglyn geplaas en dien as bron om die uitstralingspatrone te meet. Metings is uitgevoer in verskillende omgewings, insluitende 'n hoogspanningslaboratorium (HV-Lab), 'n 40 m toetslyn en 'n 22 kV WS toetslyn van ongeveer 1.5 km lank. Die hoof vonkontladings eienskappe van belang is die temporale en spektrale eienskappe. Die tydgebiedeienskappe wat ondersoek is, is die pulsvorm asook die pulsherhalingskoers. Die laterale, longitudinale en hoogte-attenuasie profiele word ook gekwantifiseer. Aangesien stroompulse deur vonkontladings op die kraglyn geplaas of geinduseer word, sal die lyn as 'n ongewenste antenna optree. Die ver-veld uitstralingskenmerke van die lyn is ook geëvalueer deur gebruik te maak van fisiese skaalmodelstrukture en -simulasies. 1/120ste en 1/200ste geskaleerde lynmodelle, wat onderskeidelik 'n absorberende- en metaalgrondvlak bevat, was gebruik om 'n 3 spanlengte kraglyn te simuleer met behulp van FEKO. Metings van die fisiese skaalmodel strukture is in 'n anegoise kamer geneem. Beide die metings en die simulasies toon dat die lyn 'n endpunt uitstralingspatroon het. Lynlengte, die opwekkingsposisie van die stroompuls en die lynkonfigurasie is 'n paar van die parameters wat die uitstralingpatroon beïnvloed, soos in die navorsing aangedui. Die bevindinge van hierdie studie word gebruik om steurnisse as gevolg van vonkontladings op die kraglyn te identifiseer, op te spoor en uiteindelik reg te stel. Toepaslike toerusting word voorgestel wat gebruik kan word vir die identifisering en opsporing van vonkontladings.