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Novos conversores CC-CC isolados ZVS-PWM com grapeamento ativo e baixa ondulação de corrente na entrada e na saídaRomaneli, Eduardo Félix Ribeiro January 2001 (has links)
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica / Made available in DSpace on 2012-10-18T07:22:49Z (GMT). No. of bitstreams: 0Bitstream added on 2014-09-25T20:38:55Z : No. of bitstreams: 1
182323.pdf: 6556730 bytes, checksum: 632ff44dadb088cd85af311cb232fa6b (MD5) / Apesar da existência de uma gama variada de conversores com características de baixa ondulação de corrente na entrada e na saída, muitas vezes estas opções são descartadas pela complexidade. Este trabalho tenta preencher esta lacuna. É apresentada uma revisão sobre os principais conversores concorrentes que aparecem na literatura especializada até o momento.
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In the middle of the corrupting sea : cultural encounters in Sicily and Sardinia between 1450 - 900 BCRussell, Anthony January 2011 (has links)
Archaeological investigations of pre-colonial contacts in Sicily and Sardinia during the Middle and Late Bronze Age (15th – 10th centuries BC) often represent such encounters as both systematic and highly influential in the development of islander societies. Discussions of the involvement and impact of Aegeans and Cypriots dominate these investigations of cultural encounters. Such studies typically discuss networks of exchange from the extrainsular perspective, focussing on trade routes and provenience analyses, which almost always involve mobile foreigners coming to these islands to establish economic relationships with passive, receptive, and stationary islanders. The dominance of these ‘acculturation’ interpretations, while understandable within the context of the history of Mediterranean archaeology, is nonetheless unfortunate, as eastern Mediterranean material consistently represents only a small fraction of material assemblages throughout the region. Often it is assumed that foreigners controlled such contacts, based on the assumption that members of a more complex society will dominate those of a simpler one. There seems to be little room, however, for interpretations which involve mobile, enterprising or self-aware Sicilians and Sardinians during this timeframe, even when it is recognised that trade networks (e.g. of Sardinian obsidian) had existed in the region since the Neolithic period. Similarly, local motivations for establishing or maintaining contacts are often ignored. My thesis employs a postcolonial perspective, even though dealing with a precolonial period. Postcolonial archaeology, however, need not be exclusively concerned with re-analysing the archaeology of colonisation, but also re-assessing the scholarship which is a by-product of the colonialist representations, such as the over-representation of contacts with eastern Mediterranean peoples, and their supposed cultural superiority. Instead, three themes of representation are employed: (1) the investigation of materials from a local, consumption-based perspective; (2) the abandonment of simplistic dualist paradigms; and (3) the recognition of the hybrid productions and practices which result from these material connections. These perspectives give a more accurate assessment of local agency, illuminate the involvement of other possible participants in the central Mediterranean, and analyse how the consumption of foreign and hybrid materials affected the development and promotion of islander identities. There is an active separation made between the presence of foreign objects and that of foreign peoples, and as a result, the cultural encounters described are interpreted as instances of object diasporas, rather than physical encounters.
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Monuments and the construction of the past in early historic IrelandAitchison, Nicholas B. January 1990 (has links)
This thesis concerns the manner in which the monumental remains of earlier human activity within the Irish landscape were perceived and investigated with meaning and value during the early historic period. This period is defined here as comprising the sixth to eleventh centuries AD. That some monuments were regarded as significant during the early historic period is indicated by the prominence which they are accorded in epic literature and topographical lore, their recording in annalistic compilations as the sites of battles and assemblies, and their spatial proximity to - or even incorporation within - ecclesiastical or royal sites.
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Commercialisation, change and continuity : an archaeological study of rural commercial practice in the Scottish HighlandsAdamson, Donald Beck January 2014 (has links)
This is a study of the movement of cattle and grain out of the Scottish Highlands in the period before and during Improvement. It uses the combined approach of historical archaeology (archaeological, documentary and cartographic research) to focus on the growth and implications of commercial practice in a predominately rural region. The growth of the cattle trade is evidenced in archaeological terms by drove roads and associated structures such as cattle stances, enclosures, bothies and inns. The thesis studies two droving routes. One is through central Sutherland, and the other in Cowal and west Loch Lomondside. The case-studies trace the route of cattle towards distant markets outside of the Highlands, and record and analyse overnight stopping places along the way. The development of a trade in grain from certain low lying fertile areas of the Highlands is evidenced by the building of grain storehouses or ‘girnals’ which were related to jetties, anchorages and harbours from which the grain was exported. The thesis considers the archaeology of the grain trade in Easter Ross, and also in the southern Highlands. Practice is central to everyday life, and the practices associated with moving cattle and grain have embedded themselves into the archaeology of the landscapes through which they passed. The seasonal routines by which drovers moved herds of black cattle or estate tenants brought grain to the girnals, and thence onto ships, were indicative of a mesh of social relationships. The material culture of the cattle and grain trades both structured and was structured by that routine practice. Thus the archaeology gives evidence of past social relationships and how they changed over time. This thesis considers for the first time the archaeological evidence for cattle and grain export from Highland Scotland. Therefore it gives a new understanding of the increasing impact of markets and market forces on social relations, as well as the tension between change and continuity in those relationships. It does not deny political or cultural drivers of change in the Scottish Highlands, but does emphasise what might be termed economic factors. It has something to say about the rise of the individual over community, and how individuals dealt with change in the light of asymmetrical power relationships. These issues still resonate in contemporary Scotland. Ultimately this study is about how people, mostly unnamed in documentary records, dealt with change, and it is about the archaeological legacy of their actions.
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Unravelling the walls of God's war : an archaeological approach to the Holy Land's Fatimid, Ayyubid, and Frankish city walls from 1099-1291Charland, Amanda Corinne Ellen January 2014 (has links)
This thesis presents a study of urban defence from a social or symbolic as well as a military perspective. For the past 150 years, Crusader castle research has provided many excellent studies. However, the field has been dominated by military historians, focussed on the evolution of architecture and debating stylistic origins. Urban fortifications are overshadowed by the imperious keeps standing within their walls unless they contribute to the discussion of military advancements. The study of these fortifications is further biased by their Frankish-centric material, rarely considering the biography of the site, thus downplaying Muslim elements. Other castle research, like that from Britain, has moved past this military focus, turning towards social or symbolic interpretations. Instead of incorporating both lines of interpretation, a divide was created leading to the interpretative straightjacket known as the ‘war or status’ rut. In order to rectify these biases and escape the straightjacket this PhD project seeks to answer the question: what are the military and social or symbolic functions of city walls? This thesis aims to: address the field’s bias by evaluating the full biography of the city walls during the Frankish era (1099–1291); take into account both Frankish and Muslim occupations of the sites; incorporate evidence of city wall use from multiple disciplines, such as history, architecture, sigillography, and art; and analyze the data using the theoretical concepts of biography, monumentality and memory. These aims are met through the case studies of Ascalon and Caesarea. By taking into account evidence from multiple fields, this thesis effectively unravels the functions of these cities’ city walls so that they are no longer limited by their military treatments. These case studies demonstrate that the city walls did not stand idly throughout the course of the Crusader era. They were used as monumental demonstrations of élite power as well as objects of civic pride and community achievement. They provided apotropaic as well as military protection against their enemies and were used to display domination and victory, demonstrating one group’s oppression and conquest over the other.
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Medieval landscapes and lordship in South UistRaven, John A. January 2005 (has links)
This thesis examines the structures of society and lordship in the Middle Ages in South Uist through historical documentation, oral-tradition, cultural landscapes, monuments and settlement patterns. In this thesis, the medieval period has been defined as that between c. 1000 and c. 1650. The historical evidence is considered along with archaeological evidence to create a holistic understanding of medieval social developments in South Uist. The results have ramifications for interpreting contemporaneous society throughout Scotland and Ireland. The study focuses on rural settlement (farms, townships, field- and transhumance-systems) and high-status monuments (churches, duns and castles). Developments visible in both the historical and archaeological record demonstrate that considerable social, economic and cultural changes took place within the landscape of South Uist throughout the Middle Ages. However, the nature of the evidence polarises the study into two time spheres: the Norse period, c. 1000 - c. 1400, and the Late Medieval period, c. 1550 - c. 1650. Remains belonging to the intervening period have proved difficult to locate. The Norse period landscape was characterised by dispersed farmsteads, possibly siting within an enclosed field-system. It is probable that these farmsteads originated as the homesteads of Viking Age settlers. Between the eleventh century and the end of the 1300s, there was a trend towards social and economic centralisation and the creation of an increasingly formalised social hierarchy: manifestations of this can be seen in the archaeological record and a new system of taxation. Archaeologically this is revealed by increasing divergence in the sizes of farmsteads, the largest of which also exhibit signs of industrial and agricultural control. Increased social differentiation is additionally reflected in artefact assemblages.
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Spatial analysis and actor-network theory : a multi-scalar analytical study of the Chumash rock art of South-Central CaliforniaWienhold, Michelle January 2014 (has links)
The aim of this research is to provide a more holistic approach to study Chumash rock art throughout their entire geographic region within South-Central California by applying geographic information systems (GIS), incorporating ethnohistoric and ethnographic data and utilising associated archaeological material under an Actor-Network Theory (ANT) framework. Through a review of past Chumash archaeological and rock art studies, I discuss where previous research is lacking and how that research was fragmentary due to focusing only on specific geographic areas or linguistic regions. As rock art is an artefact fixed within the terrain, I further argue it has a potential connection to the topography--particularly its relationship to Chumash landscapes and taskscapes by applying both formal and informed methodologies at multiple scales. By modifying the tenets of ANT to create a framework that uses the rock art data to define space, analyse its heterogeneity and connectivity and study its topographic entrenchment, this research conceptualises rock art’s networks. To conduct this research, I collated a large body of spatial and descriptive information for 254 rock art sites and associated archaeology. Spatial analyses were performed at multiple scales using GIS as a heuristic to conceptualise site clustering, landscape entrenchment and anisotropic movement for the collated data. While the rock art sites were used to define the multi-scalar spaces, results show that the identity of the sites change throughout space and time where rock art itself is a network and not exclusive to one specific Chumash network. Analysis of the data shows that the topographic setting entrenches the rock art and begins to represent the dynamic assembly of its heterogeneous network relations. Movement through the landscape reflects how the sites were connected or structured within their landscapes and taskscapes. Overall it reflects rock art’s interrelationships to the networked economic, social, ideological and political organisations of the Chumash and their rich ceremonial practices. Therefore, the Chumash rock art networks were as complex, dynamic, variable and heterogeneous as Chumash society and the rock art panels themselves.
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Technology at the transition : relationships between culture, style and function in the Late Iron Age determined through the analysis of artefactsDavis, Mary January 2014 (has links)
The principle aim of the thesis was to examine the technology of Late Iron Age decorated metal work at a time of dynamic change from both internal and external factors. The objects chosen for this study were predominantly from dry land hoards, and superficially had many aspects in common. The majority of these hoards were deposited in Britain in the mid first century AD (slightly later in the case of Middlebie in south west Scotland), and located in areas of attested historical conflict with the invading Roman army. Predominant amongst the kind of objects in the hoards were those associated with horses and carts or chariots; an artefact type of social and historical significance to native British Iron Age societies. It is argued that the manufacture, use and deposition of these objects were an important factor in maintaining relationships between different Iron Age groups in the face of threats from an invading force. Chemical analysis of objects from this period is important. The first century AD witnessed both technological sophistication and conservatism as the Iron Age metalworkers confronted the introduction, through continental influence and the Roman army, of new materials such as brass, and the re-introduction of piece moulds and leaded copper alloys. Coloured Roman glass was also introduced and used in many parts of Britain, but Insular La Tène style metalwork continued to be decorated using sealing wax red glass (a specific Iron Age technology). On the whole, an innate conservatism in object styles and materials were maintained, irrespective of acquired knowledge and the availability of new technologies. In fact, Late Insular La Tène art developed and flourished, as some indigenous Britons adopted a strong identity through the use of specific objects, technologies and artistic styles; recognisable throughout large parts of Britain.
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Isochron methods for luminescence dating in archaeologyClark, Peter Alan January 1994 (has links)
This work aims to contribute to the solution of a problem relevant to archaeology and microdosimetry, namely the TL dating of destratified archaeological ceramics. It is apparent that museums hold a large body of archaeological material excavated from important sites during the early part of this century. Absolute dating of this corpus of material would be extremely valuable to archaeology in allowing historic hypotheses to be tested. The background to this problem has been presented within the context of the historical development of thermoluminescence dating and of dosimetry concepts. A critical review of previously proposed strategies for dating material from unknown gamma contexts is presented, and then a general model using an isochron approach is introduced. The isochron model is then developed explicitly and theoretical simulation is used to explore different microdosimetric systems. Two main isochron solutions have been identified, the grain size (or alpha-beta attenuation) and alpha efficiency isochrons. An experimental approach was designed, to evaluate the validity of the grain size isochron predictions, using model matrices. Isochron behaviour was clearly observed in both cases. The first system, based on microcline feldspar grains in a high dose rate matrix, produced an age estimate consistent with the known age. The second experiment, using fluorite grains in a lower dose rate matrix, produced a highly coherent data set. However, the age estimate obtained was greater than the expected value by a factor of approximately 3. The possible reasons for this are discussed in detail. A brief experiment carried out subsequently on duplicate portion of this matrix gave results that are consistent with predicted values. Thus, it would appear that the original experimental design and method were valid and that the isochron approach does indeed deserve further investigation.
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Living in liminality : an osteoarchaeological investigation into the use of avian resources in North Atlantic Island environmentsBest, Julia January 2013 (has links)
This thesis explores the use of avian resources within the Scottish and wider North Atlantic Island environment via archaeological bone and eggshell. Birds can provide a range of products including meat, eggs and feathers, however their archaeological investigation has frequently been both overlooked, and limited in its extent and application. By collating pre-existing avian data and combining it with new, in-depth analyses this thesis investigates bird use though time and space; firstly in the Scottish Islands (the primary area of study), and then contextualises this within the wider tradition of fowling archaeologically and historically in Iceland and the Faroe Islands. Mesolithic to Norse Scottish Island bird bone is used to develop our understanding of diet, wild resource exploitation, seasonal fowling activities, habitat use, and movement around the landscape. South Uist in the Outer Hebrides forms a major case study incorporating substantial primary bone analyses from Late Bronze Age to Early Iron Age Cladh Hallan, Norse Bornais and Norse Cille Pheadair. The full Scottish Island dataset is used to consider trends in bird use by period and location. Species presence, juveniles, medullary bone and SEM analysis of eggshell are used to investigate resource acquisition by season and location. The material reveals that seabirds played an enduring role, with key birds such as the gannet, auks, shag, cormorant and gulls being repeatedly exploited. Fowling is focused and diverse, often incorporating targeted species and several opportunistically caught taxa. Birds were acquired both locally and in fowling trips further afield. Variations in avian populations are observed; determining the resources available to human fowlers and investigating the impact of such exploitation. Analysing, integrating and interpreting the archaeological bird remains on this wide temporal and geographical scale has enabled a greater understanding of past bird use and role within North Atlantic Island diet, economy and life.
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