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Thesis (M.A.)--Zheng zhi zuo zhan xue xiao. / Reproduced from typescript. Bibliography: leaves 99-102.

Orientador: Márcio Antônio Teixeira / Banca: Antônio Nivaldo Hespanhol / Banca: Sônia Maria Pessoa Pereira Bergamasco / Resumo: Este trabalho tem como objetivo a análise dos movimentos de ocupação pelas frentes pioneiras de colonização (1940-1960),que contribuíram para a apropriação e valorização das terras do Noroeste Paulista, identificando o momento dos conflitos reivindicatórios e o papel dos órgãos públicos na consolidação do projeto de colonização da Gleba 06 - Fazenda Jacylândia no município de Meridiano, estado de São Paulo . O estudo revela a evolução da estrutura agrária e fundiária, seu suporte legal no tocante a Fazenda, município e região, e analisa a situação atual dos sitiantes-residentes da Fazenda face às políticas agrárias vigentes. A localização da Fazenda (proximidade dos núcleos urbanos), o desgaste da terra, o predomínio do minifúndio, a morosidade das decisões políticas do Estado, a falta de recursos econômicos, apontou para a busca de alternativas e estratégias de sobrevivência e inclusões de atividades não-agrícolas que apontam para um "novo rural" - polissêmico. / Abstract: This work has as its purpose to analyse the movements of occupation done by the pioneer fronts of colonization (1940 - 1960), that contributed for the possession and valuation of the lands on Noroeste Paulista, by identifying the moments of the reivindicative conflicts and the role of the public organisms for the consolidation of the colonization project of the Glebe 6 - Jacylândia Farm, in the municipality of Meridiano, São Paulo state. This study shows the evolution of the agrarian, landed structure, its legal support concerning to the Farm, the municipality and the region, and it evaluates the present situation of the small farmers living on the Farm before the agrarian politics in vigor. The localization of the Farm (near the urban nuclei), the wearing of the lands, the prevalence of the small properties, the slowness of the political actions of the State, the lack of economic funds indicated the search of options and survival strategies through the non-agricultural activities that pointed towards a polysemic "new rural". / Mestre

In this limited survey, nineteenth-century cast-iron facades in Texas were recorded and compared to iron-fronted buildings in New York City. It was found that generally, the still existing buildings in Texas cities and towns were similar to those in New York in style but differed to the extent to which the cast-iron elements were used. None of the existing iron facades in Texas used iron as support beyond the first floor of the facade. This held true even in multi-storied buildings in Texas where cast-iron columns on the first floor carried the weight of a brick facade on the upper floors. It appears that nineteenth-century builders in Texas knew of New York trends but had definite regional preferences.

Density fronts are ubiquitous features of the ocean and atmosphere boundary layers. Boundary layers are characterised by strong surface fluxes of heat, water and momentum, and exhibit intense eddy fields that are associated with strong horizontal strains. Such boundary layer phenomena can drive the generation and sharpening of frontal density gradients in a process known as frontogenesis. Analytic models of frontogenesis have typically employed the `two-dimensional front' configuration where the density front is assumed to be infinitely long and straight, such that gradients along the front may be neglected, and the mathematical problem reduced to two spatial dimensions. Hoskins and Bretherton (1972) used this configuration to demonstrate how a weak background strain flow, associated with a large scale weather system, can drive the collapse of a boundary front to a discontinuity in the inviscid equations in finite time. More recently, Blumen (2000) has used the same configuration to demonstrate how an unbalanced initial state --- associated with a rapidly applied boundary flux --- can trigger an adjustment process which drives frontogenesis on the boundary. These two types of frontogenesis are known as `forced' and `spontaneous', respectively. Forced and spontaneous frontogenesis have typically been studied in isolation, despite it being well established that they can and do occur simultaneously. Furthermore, neither the Hoskins and Bretherton (1972) nor Blumen (2000) models include propagating inertia-gravity waves, despite recent observations and numerical simulations showing that these waves are often generated during active frontogenesis. Here we formulate a generalised mathematical model for the classical two-dimensional density front subject to a simple background strain flow, as studied by Hoskins and Bretherton (1972) . This model firstly unifies the disparate frontogenesis theories of Hoskins and Bretherton (1972) and Blumen (2000). Secondly, the model extends these theories by permitting arbitrary initial conditions, stratification and strong strains. Thirdly, the model incorporates non-hydrostatic effects and unbounded domains. An important novel feature of the model is the accurate description of inertia-gravity wave generation during frontogenesis. We show that these waves can be generated both by the geostrophic adjustment of initial imbalances in a stratified ambient, and spontaneously due to the acceleration of the strain flow around the front. The generalised model thus provides a unified theory capable of describing frontogenesis and wave generation in the atmosphere and ocean boundary layers on a vast range of scales. In particular, the inclusion of strong strains permits the description of frontogenesis on the ocean submesoscale. The predictions of the generalised model are confirmed by comparison with a suite of fully non-linear numerical simulations.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Bibliography: leaves 38-39. / M.S.

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Adaptive optical systems have applications in various domains: imaging (zoom and autofocus), medicine (endoscopy, ophthalmology), virtual and augmented reality. Liquid crystal-based lenses have become a big part of adaptive optics industry as they have numerous advantages in comparison with traditional methods. Despite significant progress made over the past decades, certain performance and production limitations still exist. This thesis explores ways of overcoming these problems, considering two types of tunable lenses: liquid crystal lens using dielectric dividing principle and modal control lens.The introduction of this thesis presents the theory of liquid crystals and adaptive lenses, addressing existing liquid crystal lenses as well.In the first and second chapters of this work we demonstrate the results of theoretical modeling of double dielectric optically hidden liquid crystal lens design. We have studied the influence of geometrical parameters, such as thickness of liquid crystal cell, shape and dimensions of dielectrics forming the optically hidden layer, on the optical power of the lens. The dependences of optical power on the relative permittivity and conductivity of dielectrics were obtained. The behavior of such a lens in the presence of temperature variation was analyzed. We have further extended the concept of hidden dielectric layer to exploration of microstructures. Two systems of microlenses and microprisms have been simulated. The comparison of optical phase modulation dependence on spatial frequency of microstructures was obtained. Deviations from ideal wavefronts were evaluated in both cases. We also compared proposed designs with a standard interdigital electrode approach. Suggested devices could be used for continuous light steering or as tunable microlens arrays. In the third and fourth chapters we present our studies of tunable lenses based on modal control principle. We verified simulation results by comparing them with experimentally obtained dependences of optical power and root mean square spherical aberrations. We have explored the following modifications of conventional modal control lens: 1) additional powered ring electrode; 2) floating disk electrode; 3) combination of the first two cases. The influence of each modification was studied and explained. Simulation results showed that using the combination of additional electrodes along with optimal powering technique -the wavefront could be corrected within the entire clear aperture of the lens. Modified lens meets low aberration requirements for ophthalmic applications (for example,intraocular implant). Finally, a new design of a wide aperture tunable modal control Fresnel lens was investigated. Imaging performance of the proposed Fresnel lens was evaluated and compared with the reference lens built using traditional modal control approach. The prototype device demonstrated the increase of optical powerin comparison with a conventional modal control lens of the same aperture size. A theoretical model and numerical simulations of the Fresnel lens design were presented. Simulations demonstrated a possibility of noticeable image quality improvement obtained using optimized voltages and frequencies.

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