Made available in DSpace on 2014-06-12T18:34:38Z (GMT). No. of bitstreams: 2 arquivo466_1.pdf: 1089988 bytes, checksum: 619ecdf970c5b3daa457c1fa0bbcc7e9 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Na sintaxe da complementação verbal, o sistema de muitas línguas do mundo autoriza que estruturas sentenciais ocupem a posição reservada sintaticamente ao objeto. A esse tipo de preenchimento sintático, subjazem correlações entre os domínios da sintaxe, da semântica, da pragmática e da cognição. Haja vista o português pertencer ao rol das línguas cujos verbos tomam cláusulascomplemento, o presente trabalho objetiva realizar uma análise funcional dos processos de encaixamento sintáticosemântico em construções complexas por subordinação do português falado e escrito no Brasil. Para tanto, são tomados como corpus da investigação dados de fala e de escrita coletados na cidade do Natal/RN. O material integra um corpus maior do grupo de pesquisa D&G (Discurso & Gramática), que coletou dados de fala e de escrita nas cidades do Rio de Janeiro, do Natal, do Rio Grande e de Juiz de Fora. Os textos da cidade do Natal, que são aqui postos sob estudo, correspondem a 120 produções de um total de 12 informantes igualmente distribuídos por três níveis de escolaridade: fundamental II, médio e superior. Como foram adotados cinco tipos textuais (narrativa de experiência pessoal, narrativa recontada, descrição de local, relato de procedimento e relato de opinião), cada informante produziu 10 textos, sendo 5 na modalidade falada e 5 na modalidade escrita. No que tange à fundamentação das análises, são adotadas as bases teóricas da Linguística Funcional norteamericana, dentre as quais destacamos a teoria da prototipicidade , o princípio da iconicidade e a perspectiva escalar da combinação de cláusulas. Por fim, as ocorrências do fenômeno são submetidas a um tratamento estatístico em vista a confrontar os dados de fala e os de escrita. A principal necessidade do confronto é a confirmação ou a negação da bastante difundida visão de que o âmbito da escrita é mais propício à ocorrência do fenômeno da subordinação do que o da fala

The objective of the study was to examine factors that influence the strength of butt welds and gain an understanding of the process of failure. The study was divided into several sectors. The first and primary part of the programme was to determine the extent to which the pipe system's long-term strength under both internal fluctuating and constant pressure is reduced by the presence of axially misaligned butt welds. The second objective was to examine fracture initiation sites and crack propagation paths of the failed aligned and misaligned butt welded samples in relation to the melt flow zone and the weld bead in order to establish the cause of failure. Finally the project considered the influence of selected welding parameters on the fatigue performance of aligned butt fusion welds and an investigation into the influence of elevated temperature (79°C) testing technique on the basic material's properties. Fatigue and stress-rupture lifetimes were found to decrease significantly with increasing axial misalignment at the butt fusion weld in 63,90 and 125mm MDPE pipe systems at 79°C in a water environment. In the butt fusion weld having axial misalignment of 20 per cent of the wall thickness and above, the reduction in the fatigue and stress-rupture lifetime was greater than 50 per cent compared to the aligned weld. It was not clear whether there is a pipe size effect or not; there was no marked change in the fatigue performance of misaligned butt welds for the three pipe diameters examined. However, the fatigue performance of the aligned butt welds in 90 and 125mm was noticeably better compared to 63mm pipe systems. The stress rupture performance of misaligned butt welds in 90 and 125mm MDPE pipes was more than halved compared to those in 63mm pipe systems. Both the fatigue and stress rupture performance of misaligned butt welds could be explained in terms of amplified axial stress and in general, the Ory expression for evaluating the increase in axial stress due to misalignment appears to be valid. The temperature dependence of the fatigue performance of aligned and misaligned butt fusion welds in 63 and 90mm MDPE pipe systems suggests that if continuous internal fluctuating pressure under the conditions examined is maintained, then the butt fusion welds with axial misalignment of below 10 per cent of the wall thickness may well meet the design lifetime of 50 years at the service termperature. Under stress-rupture conditions, all the misaligned butt welds considered in the three pipe diameters surpassed the minimum specified requirement of 170 hours at 79°C. The fatigue was the most aggresive condition of the two for minor misalignment. Examination of the circumferential butt weld failures revealed that the crack invariably initiated from the notch located at the inner weld bead and no preferred crack propagation path was taken in relation to the melt flow zone. It was proved that the notch was responsible for the observed circumferential failure of aligned butt welds in 63mm MDPE pipes by testing these butt fusion welds where the internal weld bead was machined off. The failure site for the internal weld bead machined off sample was in the pipe remote from the weld inferring that the material in the melt flow zone does not constitute any weakness. The effect of elevated temperature (79°C) testing in 63mm HDPE pipe was found to increase the density (and crystallinity) signifying a slow annealing process in the material. However, the changes in these parameters were not of sufficient scale to strongly influence the performance. The main effect of elevated temperature testing in water environment appears to be the extraction of stabiliser from the base polymer as was indicated by the rapid decrease in oxidation induction time with the ageing times.

Fibre reinforced structural members are currently being produced using the pultrusion process. The mechanical properties of these members are fundamentally different from those of conventional metallic ones. Therefore, the approximate theories which are suitable for designing the latter elements have to be revised before they are applied to pultrusions. An important aspect of the design of building frames is that of joints. The bolting technique is considered as the most suitable method for on-site jointing. Accordingly, experimental investigations are undertaken in order to establish the behaviour of bolted joints in pultrusions. Numerical and analytical methods are used to investigate the stresses in these joints. Single and two-bolt joints were the subject of experimental investigations. It is shown that materials with high percentage of axial fibres do not develop bearing failure. However, provided the end distance is sufficient, the resulting shear failure will be ductile. The load distribution in joints with two bolts is measured and it is found that it varies with the load on the joint. The theoretical investigations compare the use of the laminated plate theory with three dimensional analyses. Because the use of the laminated plate theory is found to be reasonably accurate, an improvement for the case of a symmetrical laminate is proposed where the laminated shell theory is used to model half the plate only. This technique is based on the assumption of a bi-linear variation of the stress through the thickness of the laminate. The effect of the fastener is an important part of the behaviour of the joints. Three dimensional analyses are performed to assess its effect. To avoid the complications of performing three dimensional analyses, a two dimensional model for considering the effect of the washer on the joint is devised. In addition, a method which avoids iteration when considering the effect of friction is formulated. A finite element formulation for the non-linear and failure behaviour of uniaxial composite materials is developed to investigate the behaviour of the joints. Finally, a closed form analytical formula for calculating the tangential stress around a hole in an infinite orthotropic plate loaded on the hole is generated to simplify the design procedures.

A generalized engineering classification method for characterizing Pleistocene glacial materials on the basis of their glaciological mode of origin is presented in this thesis. In formulating the classification an interdisciplinary approach has been adopted. The geotechnical aspects have been based largely on data from extensive site investigations undertaken at the Brenig dam site in North Wales, supplemented where necessary by data obtained from the glaciological and geotechnical literature. Particular attention has been paid to the macrofabric of the deposits in view of the controlling influence that discontinuities exert on engineering behaviour. The glaciological appraisal of the materials has also relied heavily on detailed evaluation of the engineering behaviour and textural properties of the Brenig deposits. However, in order to extend the applicability of the proposed classification to other locations, the site-specific data has been correlated with results from current glaciological research on modern arctic and temperate glaciers. As a prerequisite for such an assessment, a reconstruction of the glacial history of the Brenig site has been attempted. The similar mineralogy of the various glacial deposits and the availability of extensive geotechnical data on the complete suite of materials has made the, site ideal for this purpose. In presenting the results of the studies, the thesis has been divided into four sections. By way of background, in Part I the methodology and scope of the investigations conducted at Brenig are presented. In Part II a comparison is made between the characteristics of Recent glacial deposits and the Pleistocene materials at Brenig. The stratigraphy and glacial chronology of the site are developed in Part III, while in Part IV the geotechnical evaluation of the site is presented and set within the glaciological framework as a basis for the proposed classification.

No description available.

This thesis is concerned with layered reflections observed in the Antarctic and Greenland ice sheets during radio-echo sounding. It describes in detail layering seen with 60 and 300 MHz equipment _in the Antarctic ice sheet during three field seasons betwe~n 1974 and 1979, and discusses the effects of glaciological and equipment factors, particularly radio pulse length. The effects of changing pulse length and accumulation rate on layer echo separation are analysed, and the importance of closely spaced groups of reflectors assessed. Reflection coefficient vs depth profiles are presented for layering observed at nearly twenty sites in the Antarctic and Greenland, and are used to demonstrate the existence of two separate reflection mechanisms: changes in (a) ice density, and (b) loss tangent. Supporting density and conductivity data from ice cores are summarised. It is concluded that most layer echoes arise from layers of ice containing acidic impurities of volcanic origin~ Layer reflectivity variations_are observed over distances of tens of kilometres. Short-period fading is also observed, from which estimates of layer reflector roughness are made using the autocorrelation function and variance of the received power. The roughness estimates are shown to be consistent with a depositional origin for the surfaces. Relevant theory is summarised and a procedure developed for the remote estimation of elevated acidity levels in ice from radio-echo sounding. Such estimates are shown to compare well with direct ice core measurements. The method is used to present estimated elevated acidity profiles for the Antarctic (to ~100 kaBP) and Greenland (to ~30 kaBP), which are interpreted in terms of variations in the input of volcanogenic acid impurities to the ice sheets. The use of layering as isochronous horizons in ice flow studies is discussed in the light of new measurements, with particular emphasis on t he zone close to bedrock.

Active microwave sensors are known to provide valuable information regarding snow and ice surfaces in the polar regions, where darkness and cloud cover prevail. Here, data collected in the Arctic by a Ku-band microwave radar altimeter, designed and constructed in the UK, are analysed. The two main components of this study comprise data gathered in the East Greenland Sea marginal ice zone and over two Svalbard ice caps. A systematic treatment is made of the electromagnetic properties of snow and ice at 13.81 GHz, and the differences between various polar surface media are highlighted. Theoretical and empirical models are presented which enable calculation of the relevant dielectric and scattering properties of snow and ice layers. Parametric studies are undertaken to give insight into the range of scattering conditions likely to be encountered by a radar altimeter in the regions investigated. Examples of altimetric data and results of their analysis are presented, demonstrating the effects of different ice types and terrain upon incident altimeter pulses. Waveforms are characterised by their shape, and certain forms are linked with particular physical properties of the surface. To this a variety of supporting information is added in order to verify and validate interpretations of these results. Algorithms are proposed which enable geophysical information to be derived from altimetric data.

The growth of the Weddell Sea ice cover in 1980 is examined, using Nimbus-7 satellite Scanning Multi-channel Microwave Radiometer (SMMR) data in combination with data (positional, air temperature and atmospheric pressure) from 4 Nimbus-tracked drifting buoys. Ice concentrations are retrieved from the SMMR data by applying a cluster analysis algorithm developed by J. Comiso of NASA. Analyses of computed differential kinematic parameters (DKP)s of the buoy array offer insight into the complex mesoscale behaviour of the underlying Weddell Gyre. High frequency divergence, convergence and deformation events isolated in the DKP results, and driven largely by the regular passage of cyclones, are related to changes in ice concentration observed in the SMMR data. The profound role of the Antarctic Peninsula in influencing both atmospheric and oceanic circulation (and thus ice formation, drift and eventual decay) in the region is evaluated. Possible relationships between buoy drift in the inner pack and ice edge advance are examined, yielding information on the relative importance of ice growth in open water within the pack and that at the ice edge. After an introductory chapter, Chapter 2 describes the physical setting of the Weddell Sea. Comparisons are drawn both with other sectors of the Southern Ocean and the Arctic, emphasizing the uniqueness of the region not only in terms of its climate and oceanography but also its sea ice cover. Chapter 3 traces the evolution of passive microwave remote sensing from space as a tool for monitoring Antarctic sea ice extent and concentration; the relative merits and disadvantages of these techniques are evaluated. Chapter 4 concentrates on the use of SMMR data. Detailed comparisons are made of algorithms available for the extraction of ice concentrations from the raw brightness temperature data. The choice of algorithm used is justified. Chapter 5 is largely concerned with the analysis of the buoy data, and the kinematic behaviour of the array as a unit. These results are combined with the SMMR data in Chapter 6 to identify distinct dynamic zones and meridional advective sectors, and to compare the behaviour of the inner pack with that of the unconstrained ice edge. The evolution of a high concentration core within the unique perennial sea ice zone hugging the east coast of the Peninsula, which persists throughout the period of study is unusual enough to merit a separate sub-section. Conclusions are drawn in chapter 7.

been used to investigate the form and topography of the Antarctic ice sheet and to relate these to the physical processes of ice flow and basal conditions. Topographic roughness typically increases towards the thin ice of coastal reg ions as surface undulation wav el eng ths decrease and amplitudes increase. Temperature and velocity variations also have significant effects. The coastal zone is punctuated by embayments of severe topography immediately inland of outlet glaciers. This topographic variability has been summarized in a statistical model for the purposes of simulating satellite radar altimeter waveforms. Consideration of the relationship between bedrock and surface profiles has shown that ice temperature is a major influence on the response of the surface to bedrock irregularities. Regional subglacial water layers may al so have an important effect on surface topography. A re-analysis of models of longitudinal stress grad i ents suggests that er ystal fabrics favouring faster flow develop with distance from ice divides and that the relative depth of the zone of maximum shear fluctuates in response to topographic and glaciological constraints. Driving stress patterns have been associated with characteristic glaciological regimes and have suggested a qualitative difference between outlet glaciers and ice streams. The transition to high velocity flow in outlet glaciers has been shown to be triggered ab ruptly in response to subglac ial fjord heads. The dependence of fast flow on subglacial topography indicates a significant stabilizing effect on discharge from ice sheets and suggests that surge behaviour is unlikely within existing ice sheet outlets. The onset of basal sliding at the head of subglac ial fjords suggests a mechanism for the production of overdeepened fjords and steep headwalls through concentrated erosion. This may help in the reconstruction of the dynamics of former ice sheets. Some West Antarctic ice streams do not exhibit this rapid transition in behaviour.

No description available.