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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Foundations for Multi-level Ontology-based Conceptual Modeling

CARVALHO, V. A. 16 December 2016 (has links)
Made available in DSpace on 2018-08-02T00:04:06Z (GMT). No. of bitstreams: 1 tese_10529_foundations_for_ontology_based_multi_level_conceptual_modeling_2012 - victorio.pdf: 6142526 bytes, checksum: 3e3483b04f4e9b86ab648e66104ac1e2 (MD5) Previous issue date: 2016-12-16 / Considerando que modelos conceituais são produzidos com o objetivo de representar certos aspectos do mundo físico e social de acordo com uma conceituação específica e que ontologias buscam descrever conceituações, tem havido crescente interesse no uso de ontologias para fornecer uma base teórica sólida para a disciplina de modelagem conceitual. Esse interesse deu origem a uma área de pesquisa denominada modelagem conceitual baseada em ontologias, com avanços significativos na modelagem conceitual nas últimas décadas. Apesar desses avanços, a modelagem baseada em ontologias não provê suporte adequado à modelagem de domínios que exigem a representação de categorias de indivíduos e de categorias de categorias (ou tipos de tipos). A representação de entidades de vários "níveis" de classificação tem sido o foco de uma área de pesquisa distinta denominada modelagem multi-nível. As iniciativas em modelagem multi-nível visam a contornar as limitações impostas pelo paradigma convencional de modelagem em dois níveis. Apesar das contribuições relevantes das áreas de modelagem multi-nível e de modelagem conceitual baseada em ontologias, a combinação dessas duas áreas ainda não recebeu a devida atenção. Este trabalho explora essa lacuna propondo o uso combinado de teorias formais para a modelagem multi-nível e de ontologias de fundamentação para apoiar o que chamamos de modelagem conceitual multi-nível baseada em ontologias. Para fornecer uma abordagem bem fundamentada à modelagem conceitual multi-nível, desenvolvemos uma teoria chamada MLT. MLT caracteriza formalmente a natureza dos níveis de classificação e define precisamente as relações que podem ocorrer entre elementos de diferentes níveis de classificação. A fim de aproveitar os benefícios do uso de ontologias de fundamentação na modelagem de domínios que abrangem vários níveis de classificação, combinamos MLT com uma ontologia de fundamentação. Essa combinação resulta em uma abordagem de modelagem que apoia a construção de modelos conceituais multi-níveis em um espectro de níveis de especificidade, desde ontologias de fundamentação até modelos conceituas de domínios específicos. Para demonstrar a aplicabilidade da nossa abordagem de modelagem conceitual multi-nível baseada em ontologias, a empregamos para desenvolver uma ontologia núcleo para estruturas organizacionais, um domínio que abrange vários níveis de classificação. Além disso, mostramos como MLT pode ser usada como uma teoria de referência para esclarecer a semântica e aumentar a expressividade de UML no que diz respeito à representação de modelos de multi-níveis. O perfil UML produzido viabiliza a aplicação prática de MLT pela comunidade de modelagem conceitual.
262

Requisitos ambientais para disposicao final de rejeitos radioativos em repositorios de superficie

RADUAN, ROSANE N. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:38:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:47Z (GMT). No. of bitstreams: 1 05660.pdf: 7392125 bytes, checksum: eb370b9192c312fd26fdb86ad9ed35bc (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
263

Transferability of community-based macro-level collision prediction models for use in road safety planning applications

Khondaker, Bidoura 11 1900 (has links)
This thesis proposes the methodology and guidelines for community-based macro-level CPM transferability to do road safety planning applications, with models developed in one spatial-temporal region being capable of used in a different spatial-temporal region. In doing this. the macro-level CPMs developed for the Greater Vancouver Regional District (GVRD) by Lovegrove and Sayed (2006, 2007) was used in a model transferability study. Using those models from GVRD and data from Central Okanagan Regional District (CORD), in the Province of British Columbia. Canada. a transferability test has been conducted that involved recalibration of the 1996 GVRD models to Kelowna, in 2003 context. The case study was carried out in three parts. First, macro-level CPMs for the City of Kelowna were developed using 2003 data following the research by GVRD CPM development and use. Next, the 1996 GVRD models were recalibrated to see whether they could yield reliable prediction of the safety estimates for Kelowna, in 2003 context. Finally, a comparison between the results of Kelowna’s own developed models and the transferred models was conducted to determine which models yielded better results. The results of the transferability study revealed that macro-level CPM transferability was possible and no more complicated than micro-level CPM transferability. To facilitate the development of reliable community-based, macro-level collision prediction models, it was recommended that CPMs be transferred rather than developed from scratch whenever and wherever communities lack sufficient data of adequate quality. Therefore, the transferability guidelines in this research, together with their application in the case studies, have been offered as a contribution towards model transferability to do road safety planning applications, with models developed in one spatial-temporal region being capable of used in a different spatial-temporal region. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
264

A study of the application of imaging charge-coupled devices for the detection and quantitation of luminogenic assays

Haggart, Robert January 1990 (has links)
Low light level imaging devices have the advantage that they can produce quantitative two dimensional images. The characteristics, structure and operation of different low light level imaging devices are discussed. Cooled slow scanned charged coupled device (CCD) cameras show good detector properties; very low dark noise; low system noise; good spatial resolution; therefore seem ideal for the detection and quantitation of luminogenic assays.
265

An Enhanced Inventory of Global Dams and Reservoirs and Their Contribution to Sea Level

Walter, Blake January 1900 (has links)
Master of Arts / Department of Geography / Jida Wang / In the 1950s-60s, the world was experiencing a dramatic increase in artificial water impoundments in an unprecedented effort to eliminate spatial and temporal variations in water accessibility. Dam construction has since decreased, but recently, efforts to supply water and power to a booming world population may once again spark another dam construction boom. Water supplies in some regions are already highly stressed in an effort to satisfy the ever-growing water demand for agriculture, industrial, and domestic uses. With nearly 30% of the world’s population living in water-scarce regions, an improved understanding of total stored surface water has never been more needed. Yet, a complete and spatially-explicit, worldwide inventory of such storage capabilities is lacking. Using several open-source dam registries and high-resolution global lake mapping datasets extracted from thousands of Landsat images, we here aim to provide an updated and spatially-explicit inventory of dams and artificial reservoirs across the world. The following research uses novel techniques to merge 5 authoritative, open-source dam registries into a single dam and reservoir dataset, which we deemed as the Global Dam and Reservoir Inventory (GDRI). In total, GDRI documents 89,500 dams and 83,767 reservoirs for a total capacity of 8,492km3 and total surface area of 754,551km2. Reservoirs account for approximately 2.5% of the Earth’s terrestrial water. In other words, 1 unit of water for every 40 units has been artificially created. Further downscaling of the non-geocoded records provided by the International Commission of Large Dams (ICOLD) using similar geocoding methods allowed for the thorough use of all available ICOLD records. Additional capacity estimates from downscaled ICOLD records increased the GDRI capacity documentation to 8,603km3 and surface area documentation to 859,271km2. Compared to its counterpart, the Global Reservoir and Dam dataset (GRanD), GDRI increased the number of dams documented by 1204%, reservoirs by 1127%, total capacity by 37%, and total surface area by 68%. Initial water impoundment from dam construction activities can lower sea level by permanently trapping water storage on land. Dam construction resulted in an equivalent sea level drop (SLD) of 23.4mm or 0.08mm/yr. Since the dam construction boom of the 1950s-1960s, yearly SLD increased to 0.27mm/yr. By considering the hydrological characteristics of dam location, in terms of endorheic and exorheic basins, we found that exclusion of endorheic located dams decreases the overall effect on SLD by 5.47% or 1.28mm. Failure to consider the hydrologic characteristic of dam location can result in the overestimation of dam-induced SLD. After the dam construction boom of the 1950s-1960s, the world has seen a decreasing trend in dam construction, but developing countries (China, Brazil, India) are still actively pursuing dam projects that are larger and more ambitious than ever before. We see less developed countries often lack the capabilities for dam construction possibly increasing stress on natural water supplies in those regions. The datasets produced are by no means perfect. Overall, the described procedures should be considered a heuristic model, where fastidious quality assurance and automated procedures work to thoroughly eliminate many of the issues encountered with the dataset production, but errors may still exist. However, duplication between the contributing dam datasets, spatial limitations of the lake datasets, imperfect geocoding procedures, and inclusion of more dam datasets provide opportunity for future refinement and improvement of the datasets. This research contributes vital information about anthropogenic water resources that incrementally enhances our knowledge of global hydrology and the interactions taking place between different water entities.
266

Nuclear level densities and gamma-ray strength functions in Ta isotopes and nucleo-synthesis of ¹⁸ᴼTa

Malatji, Kgashane Leroy January 2016 (has links)
>Magister Scientiae - MSc / Most stable and extremely low abundance neutron deficient nuclei with Z ≥ 34 are referred to as p-nuclei. Nearly all p-nuclei with A < 110 are most likely produced in the rp-process while almost all A > 110 are thought to be produced by the photodisintegration of s- and r- process seed nuclei. However, for some nuclear systems, these processes are not sufficient to explain their observed solar abundance. Results from calculations in ¹⁸ᴼTa generally provoke debates since several processes are able, sometimes exclusively, to reproduce the observed ¹⁸ᴼTa abundance in the cosmos, making it a unique case study. Some of the main sources of errors in the predicted reaction rates of ¹⁸ᴼTa arise due to the absence of nuclear data or due to large uncertainties in the nuclear properties such as the nuclear level densities (NLD) and gamma-ray strength functions (γSF) of ¹⁸ᴼ,¹⁸¹Ta. The NLD and γSF are primary ingredients for astrophysical reaction rate calculations based on the Hauser-Feshbach approach. These parameters need to be well understood to improve our understanding of ¹⁸ᴼTa production in astrophysical environments. In this thesis, new experimental data for the low-energy part of the γSF and NLD in ¹⁸ᴼ,¹⁸¹Ta were extracted, using the so-called Oslo method. An experiment was performed and the NaI(Tl) gamma-ray array and silicon particle telescopes at the Oslo cyclotron laboratory were utilized to measure particle-γ coincidence events from which the NLDs and γSFs are extracted below the neutron separation energy threshold Sn. A beam of ³He was used to populate excited states in ¹⁸ᴼ,¹⁸¹Ta through the inelastic scattering (³He,³He’𝛾) and the transfer reaction (³He,𝜶𝛾). Based on results from this measurements, the Maxwellian averaged (n, 𝛾) cross sections for the 179Ta(n, γ) and ¹⁸ᴼTa(n, 𝛾) reactions, at the s-process thermal energy of kT = 30 keV (i.e. a temperature of T = 3.5 × 10⁸ K) and p-process thermal energy of 215 keV (T = 2.5 × 10⁹ K), respectively, were computed with the TALYS reaction code. These results can be used to place the nuclear physics aspects of the large network abundance calculations on a solid footing and have potential to improve our understanding of the astrophysical processes and sites involved in the production of nature’s rarest isotope ¹⁸ᴼTa. / National Research Foundation (NRF)
267

Geochemical consequences of Cretaceous sea level rise

Bata, Timothy Peter January 2016 (has links)
During the Cretaceous, the CO2 content of the global atmosphere increased in response to the volcanism associated with the disintegration of the former continents. This led to a considerable rise in global temperatures, leading to a significant rise in the global sea level and the landward movement of coastlines. Cretaceous marine strata transgressed directly on the underlying basement or much older sedimentary strata. Extreme environmental conditions in the Cretaceous involved a possibly more acidic and chemically destructive atmosphere than at present, which favoured widespread deep weathering at that time. The extensive Cretaceous palaeo-seaways played a vital role in transporting and depositing the huge volume of sediments generated during the weathering events, which included economically important placer deposits (e.g., gold, diamond and platinum). A direct consequence of the extreme Cretaceous global warmth was the widespread development of Cretaceous silcretes. Much of the world's heavy oil occurs in Cretaceous reservoir sands. The geological processes responsible for the widespread occurrence of the Cretaceous oil sands can also be traced back to the unique Cretaceous greenhouse climatic condition. The warm climatic conditions imply a higher heat flow regime in the subsurface, which contributed to the thermal maturation of the organic rich sediments that are closely associated with the Cretaceous transgressive sands. The oils were generated as conventional light oil, which later degraded into heavy oils, rather than thermally cracked oils from over-matured source rocks. Oils migrated into shallow warm reservoir sands that were favourable for microbial activities. All the studied Cretaceous oil sands show evidence of hopane degradation without the formation of 25-norhopanes despite diasterane degradation in some of the samples. This strongly implies that biodegradation in these studied Cretaceous oil sands occurred at shallow depths. Pyrite precipitated from an open system by means of microbial sulfate reduction as part of the biodegradation process.
268

IMPLEMENTACE NÁSTROJŮ SLM (SERVICE LEVEL MANAGEMENTU) V KORPORÁTNÍM PROSTŘEDÍ / Implementing SLM tools in corporate environment

Chaloupka, Vladimír January 2007 (has links)
Tato práce si klade za cíl seznámit studenty i profesionály z oblasti IT o čem disciplína Service Management (SM) a proces Service Level Management (SLM) je v prostředí korporátní společnosti. Práce obsahuje příklady různých SLM nástrojů a metod, které jsou skutečně používány (například v manažerském nástroji typu Balanced Scorecard). Zvláštní důraz je kladen na překážky, jež mohou nastat a jak je překonat. Tak jako každá zkušenost toto je pouze jeden z přístupů k SLM, ale pokud přispěje k lepšímu osvícení čtenáře, pak splnila svůj cíl. K dosažení těchto záměrů využívám svých dvou a půl letých zkušeností z práce na projektech ve společnosti DHL a ostatních zdrojů popisujících teoretickou rovinu. První část mé diplomové práce poskytuje teoretickou znalost problematiky, druhá část pak převádí tyto znalosti do podnikové praxe.
269

Theoretical spin dynamics on muonium level-crossing resonance

Yen, Hon Kit January 1988 (has links)
Redfield's theory and the theory of master equations have been reviewed and their applications to muonium spin dynamics discussed. It was found that both theories are equivalent in the Markov limit. In some cases, analytical expressions for relaxation rates are found. In addition, Redfield's theory was applied to describe spin relaxation of muonium-substituted free radicals near level-crossing resonances. Theoretical predictions were compared with experimental data for the C₆F₆-Mu radical and the results suggest there are several relaxation mechanisms involved. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
270

Sublevel open stoping : design of the O640, L651 and N659 sub-level open stopes in the 3000 orebody of the Mount ISA copper mines, Queensland, Australia

Sloane, Lomar 11 July 2011 (has links)
This dissertation will explore the process followed in the design of a sub-level open stope (SLOS) by using examples of actual stopes scheduled to be in production between August 2006 and February 2007. The main objective is to give the reader an understanding into sub-level open stoping and the design process followed. The objective here is to present a design methodology applicable to sublevel open stoping, but also to then bridge the gap between theory and practice by applying said methodology to an actual design example. The design examples used in this dissertation is based on the O640, L651 and N659 stopes in the 3000 Orebody of Xstrata Copper Operation’s Mount Isa Mine, located in North-West Queensland, Australia. The actual design reports as required by the mine are attached in Annexure 1 through 3. Given the similarities of the designs, only O640 will be analysed comprehensively within the main content of this report, with L651 and N659 discussed specifically insofar issues that were unique to these stopes. With the design of O640, all aspects or design considerations as stipulated in the design process were discussed and analysed so as to define the final stope shape. These design considerations include: <ul> <li> Faulting</li> <li> Grade Contours</li> <li> Existing Development</li> <li> Surrounding Fill masses</li> <li> Rock Mechanics</li> </ul> Once the the final stope shape has been set, options regarding stope extraction will take place. This is where the initial stope layout takes place and where the engineer looks at the advantages and disadvantages of all the different options available in mining the stope. In this phase, the most effective extraction option is decided upon. Once the engineer have decided a final stope shape and extraction option, the stope will be analysed in further detail referring to drilling, the amount of drawpoints, ventilation and other stoping requirements. These are all defined as stope design features and are considered a general summary of the stope design. The design features phase is closely followed with all the safety considerations that have been taken into account since the stope design started. Main concerns and stope specific safety issues are discussed and possible solutions given. It is part of the work of the mine planning engineer to anticipate all possible safety issues and make the production department aware of what can be expected during the development, mining and filling activities of every stope. At this stage the design of the stope nears completion. The remainder of the design now goes into more detail and addresses the critical tasks that from part of sub-level open stoping. These include: <ul> <li> Reserves and Scheduling</li> <li> Development and Drilling</li> <li> Production and Firing (Blasting)</li> <li> Ventilation</li> <li> Services</li> <li> Filling</li> <li> Economic Analysis</li> </ul> Although all of the abovementioned have already been mentioned during the design features phase, it is still required to give additional details so the different departments involved have an accurate idea of what to expect, when to expect it and therefore be able to sufficiently plan for it. It must be noted that it does happen that something may be “discovered” during any stage of the final design, which may render the current design undesirable. When this happens the stope must be re-designed until all issues have been resolved or at the least have been managed appropriately. Even though this report does not go into detail with the L651 and N659 designs, these designs are included as they bring to light issues that may arise that are unique to individual stopes. L651 looks at how a design drastically changes when ore not planned for is discovered. N659 looks at what happens when a stope is the first to be mined in an area with inadequate infrastructure. The main content of the dissertation discusses and explains the design procedure as it would take place at Mount Isa Mines, but it is still quite difficult to follow logically. For this reason a flowchart was included to give the reader a more comprehensive summary of the design process. / Dissertation (MEng)--University of Pretoria, 2011. / Mining Engineering / unrestricted

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