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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.
41

Controles geoarqueológicos e modelos morfoestratigráficos: implicações para o estudo das ocupações pré-históricas na costa sul-sudeste do Brasil / Geoarchaeological Controls and Morphostratigraphic Models: implications for the study of prehistoric occupation on the south-southeast coast Brazil

Laércio Loiola Brochier 18 February 2009 (has links)
A presente tese refere-se a uma proposta de abordagem geoarqueológica voltada ao estudo de sítios arqueológicos costeiros, enfocando pressupostos teóricos e metodológicos ligados à uma aproximação entre a Arqueologia, Geociências e Ciências da Informação. Objetivou em um primeiro momento, inserir questões e problemáticas relativas a necessidade de inclusão da incerteza no raciocínio e práticas arqueológicas, vislumbrando as possibilidades de seu tratamento. Neste sentido, a percepção do \"problema da não informação\" constituiu o argumento conceitual para a elaboração de um modelo de raciocínio dialético sobre a aquisição, geração, seleção e transmissão de informações na disciplina. Nessa perspectiva, sobreveio a necessidade da interação constante entre Teorias de Formação e de Recuperação, como passo essencial ao controle das perdas e ganhos informacionais e, ao tratamento das imperfeições, incompletudes, imprecisões e ambiguidades ligadas aos fenômenos arqueológicos e seu registro científico. Um dos aspectos explorados refere-se à percepção das incertezas e vieses envolvidos na interpretação das ocupações costeiras, notadamente quanto às problemáticas de origem e migração das primeiras populações nessas áreas. Em um modelo atual dicotômico entre o interior e o litoral, onde mesmo os sítios mais antigos (somente sambaquis) acham-se dispostos sobre a superfície dos terrenos, a percepção da dinâmica e complexidade dos sistemas costeiros, fica restrita ao enquadramento desses sítios em sucessões de cenários geomórficos e paeogeográficos. Deste modo, pouca atenção é dada às conseqüências de agentes dinâmicos sobre a configuração e seleção de sítios na atual paisagem costeira, bem como, à possibilidade de ocorrência e detecção de diferentes classes de sítios, que foram preservados em profundidade por meio de processos de capeamento sedimentar. Assim, em um segundo momento, foi proposto à utilização do conceito de \"Controles Geoarquelógicos\" (CG) no estudo e explicitação dos condicionantes naturais e analíticos envolvidos em uma pesquisa de caráter regional, cujo enfoque está nas relações informacionais estabelecidas entre sítios arqueológicos e meio (natural e analítico), e cujo resultado (síntese dialética) compreenderia a noção de evento arqueológico. Diante da explicitação da variabilidade envolvida na caracterização do Registro Arqueológico Regional (RAR), bem como, dos condicionantes complexos derivados da estrutura, dinâmica e evolução da paisagem, o evento arqueológico considerado na tese, compreendeu a investigação da probabilidade de preservação de sítios costeiros antigos (teoria de formação) e do seu potencial de detecção (teoria de recuperação). Neste sentido foi utilizado o raciocínio abdutivo para gerar hipóteses sobre a preservação ou não de sítios encobertos, tendo por base os modelos sedimentares e morfoestratigraficos produzidos para a costa sul-sudeste. Por sua vez, a busca de indicadores nas planícies costeiras de Guaratuba-PR e de Caraguatatuba SP, possibilitou apontar condicionantes (variáveis) favoráveis a geração de um modelo de trapeamento de sítios (capeamento e preservação sedimentar) para a região da Baía de Guaratuba. Por fim, foi testado o raciocínio probabilístico Bayesiano e a Teoria de Evidências (Dempster-Shafer) para a inclusão e representação da incerteza na pesquisa de sambaquis, visualizando um método de tratamento das evidências e inferências geradas em sistemas baseados em conhecimento. Esses mesmos métodos também permitiram determinar os pesos para os diferentes indicadores, e as condições de necessidade, suficiência e ambigüidade das variáveis na geração de mapas aplicados à predição da favorabilidade e suscetibilidade de sítios arqueológicos enterrados na planície costeira de Guaratuba. / This thesis refers to a proposal for a geoarchaeological approach focused on the study of coastal archaeological sites, concentrating on theoretical and methodological assumptions related to a closeness between the archeology, the Information Sciences and Geosciences. It aimed in a first moment, to insert issues and problems concerning the need for inclusion of uncertainty in archaeological reasoning and practice, foreseeing the possibilities of their treatment. In this sense, the perception of the \"no information problem\" was the argument for the conceptual development of a model of dialectical thinking about the acquisition, generation, selection and transmission of information in the discipline. Accordingly, the need for constant interaction between Formation and Recovery Theories became an essential step to the control of informational losses and gains, and the treatment of imperfections, incompleteness, inaccuracies and ambiguities relating to archaeological phenomena and their scientific record. One of the aspects exploited, is the perception of slants and uncertainties involved in the interpretation of coastal activities, notably on issues of origin and migration of the first people in those areas. In a current dichotomic model between the interior and the coast, where even the oldest sites (only sambaquis) are found placed on the surface of the land, the perception of the complexity and dynamics of the coastal systems, is restricted to the framework of these sites in a succession of geomorphic and paleogeographics \"scenarios\". Thus, little attention is given to the dynamic agents consequences on the configuration and selection of sites in the coastal landscape, and the possibility of occurrence and detection of different classes of sites, which were preserved indepth by a sedimental capstone process. Therefore, in a second moment, it was proposed to use the concept of \"geoarchaeological control \" (GC) in the study and explanation of natural and analytical conditions involved in a research of regional manner, whose focus is on the informational relations established between archaeological sites and the environment (natural and analytical), whose result (dialectical synthesis) understand the concept of the archaeological event. Given the explicit characterization of the variability involved in the Regional Archaeological Record (RAR), as well as the complex condition agent derived from the structure, dynamics and evolution of the landscape, the archaeological event considered in the thesis, understand the research of the probability of preservation of ancient coastal sites (formation theory) and its potential for detection (recovery theory). In this sense abdutive reasoning was used to generate hypotheses about the preservation or not of covered sites, based on the sedimentary and morphostratigraphic models produced for the south-southeast coast. In turn, the search for indicators in the coastal plains of Guaratuba- PR and Caraguatatuba-SP, it made possible to point constraints (variables) favorable to the generation of a trap model for sites (sedimental capstone and preservation) for the region of Guaratuba Bay. Finally it was tested the probabilistic bayesian reasoning and Evidence Theory (Dempster-Shafer) for the inclusion and representation of uncertainty in the research of sambaquis foreseeing a method of treatment of the evidence and inferences generated by knowledge-based systems. These methods also allowed to determine the weights for different indicators, and the conditions of necessity, sufficiency and ambiguity of the variables in the generation of maps applied to the prediction of favorability and susceptibility of buried archaeological sites in the coastal plain of Guaratuba.
42

Distribuição de musgos (Bryophyta) no Brasil: riqueza, endemismo e conservação

Amorim, Eduardo Toledo de 16 August 2017 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-01-08T16:35:29Z No. of bitstreams: 1 eduardotoledoamorim.pdf: 7085942 bytes, checksum: 0064c64ba9943c302c39ab2df413436b (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: Favor corrigir Co-orientador: Neto, Luiz Menini on 2018-01-23T11:08:07Z (GMT) / Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-01-23T12:54:03Z No. of bitstreams: 1 eduardotoledoamorim.pdf: 7085942 bytes, checksum: 0064c64ba9943c302c39ab2df413436b (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-01-24T13:27:56Z (GMT) No. of bitstreams: 1 eduardotoledoamorim.pdf: 7085942 bytes, checksum: 0064c64ba9943c302c39ab2df413436b (MD5) / Made available in DSpace on 2018-01-24T13:27:56Z (GMT). No. of bitstreams: 1 eduardotoledoamorim.pdf: 7085942 bytes, checksum: 0064c64ba9943c302c39ab2df413436b (MD5) Previous issue date: 2017-08-16 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Bryophyta (musgos) compõem a segunda divisão mais diversa de plantas terrestres, com aproximadamente 13.000 espécies. Vários trabalhos foram realizados com o intuito de compilar o conhecimento da flora de briófitas para o Brasil, apontando os estados com o maior número de espécies e evidenciando as carências de amostragem para o país. Entretanto, ainda não se sabe de forma mais precisa, quais as lacunas no conhecimento dos musgos no Brasil. Um dos temas principais na biogeografia é compreender o motivo de espécies apresentarem ampla distribuição ou endemismo. Endemismo, objeto deste estudo, está relacionado à ocorrência restrita de um táxon, por terem se originado neste local e não terem se dispersado, ou porque ficaram restritos à área, em relação a sua distribuição anterior. Atualmente, destacam-se duas hipóteses alopátricas mais próximas para modelos de diversificação: Hipótese de Refúgio no Pleistoceno e de Isolamento em Montanhas. No Brasil, as áreas são protegidas através das Unidades de Conservação (UCs), as quais, de modo geral, são abrigadas para que se minimizem as ações antrópicas, tornando-as habitats excelentes para a colonização de briófitas. O presente trabalho teve por objetivo geral realizar um estudo sobre a distribuição de musgos para o Brasil, identificando a riqueza e o endemismo no país e apresentando uma abordagem conservacionista para as espécies Foi realizado um levantamento dos dados para as ocorrências de musgos, através de diferentes bancos de dados on-line e bibliografia. Posteriormente, esses dados foram refinados quanto à identificação em nível específico, à validade taxonômica e às coordenadas geográficas. Em seguida, foram marcados os pontos dos registros no mapa e, elaborado o gradeamento por quadrículas de 1° x 1°. A partir daí, foram realizadas as análises de riqueza, riqueza estimada, número de registros e a Análise de Parcimônia de Endemismos (PAE). Foi utilizada a ferramenta de modelagem preditiva de distribuição de espécies para identificar as áreas de maior adequabilidade para espécies endêmicas do Brasil e para elaborar um mapa de áreas de concentração de endemismo dessas espécies no país. No total, foram levantados 26.691 registros, representando 868 espécies de musgos. Foram estabelecidas 394 quadrículas, tendo o número de espécies por quadrícula variado de 1 a 235. A Floresta Atlântica apresentou maior riqueza, tanto pelas condições que fornece ao estabelecimento dos musgos, quanto à maior intensidade amostral no Domínio. A PAE resultou em apenas uma área de endemismo localizada no centro do Estado da Bahia, no Domínio Fitogeográfico da Caatinga, na região do Parque Nacional da Chapada Diamantina. As quadrículas propostas como áreas potenciais de endemismo foram encontradas em seis áreas, dispersas no Cerrado e na Floresta Atlântica. As áreas de endemismo de musgos são, em sua maioria, áreas de montanhas, que corroboram as principais hipóteses de especiação dos organismos. Dentre as UCs, 218 apresentaram áreas com adequabilidade ambiental para a presença da espécie, das quais, 68 estão inseridas nas categorias de Uso Sustentável e 150 na categoria de Proteção Integral, demonstrando a importância das UCs para a brioflora na Floresta Atlântica. / Bryophyta (mosses) are the second most diverse division of terrestrial plants, with about 13.000 species. In order to compile the knowledge of the bryophyte flora for Brazil, a range of studies were developed showing the States with the largest number of species and evidencing the lack of sampling for the country. However, the deficiency in the knowledge of mosses in Brazil is not yet known precisely. One of the main themes in biogeography is to understand why species are widely distributed or endemic. Endemism is related to the restricted occurrence of, because they originated in this place and did not disperse, or because they were confined to the area, in relation to its previous distribution. Two allopatric hypotheses are most relevant for diversification models: Pleistocene Refuge and Montane Isolate Hypothesis. In Brazil, the preserved areas are protected through Conservation Units (UCs), which have low degradation traits, making it an excellent habitat for the colonization of bryophytes. Thus, the main aims of this work were to study the distribution of mosses in Brazil, identifying the richness and endemism in the country and to present a conservationist approach to mosses species. Firstly, in order to compile information on the occurrence of mosses, we did a survey of the data through different online databases and bibliography. Subsequently, we refined these data regarding the identification at the specific level, the taxonomic validity and the geographic coordinate. Then, we marked the points of the records on the map, and we elaborated the grids by squares of 1° x 1°. Therefore, we performed analyzes of richness, estimated richness, number of records and the Parsimony Analysis of Endemicity (PAE). We used the species distribution predictive modelling to corroborate the existence of areas of endemism in Brazil and to elaborate a map of endemism clustering areas. Of the total, we collected 868 species of mosses from 26.691 records. From this information, we filled a number of 394 squares, having the number of species per grid ranging from 1 to 235. The Atlantic Forest presented greater richness, both by the conditions that it provides to the establishment of moss, and the greater sampling intensity in the Domain. The PAE resulted in only one area of endemism, located in the center of the State of Bahia, in the Phytogeographical Domain of the Caatinga, in the region of the Parque Nacional da Chapada Diamantina. The grids proposed as potential areas of endemism were found in six areas, scattered in the Cerrado and in the Atlantic Forest. The areas of endemism of mosses are mostly areas of mountains, which corroborate the main hypotheses of speciation of the organisms. In the UCs, 218 showed areas with environmental suitability for the presence of the species, whereupon 68 are inserted in the categories of Sustainable use and 150 in the category of integral protection, demonstrating the importance of the UCs for the bryoflora in the Atlantic Forest.
43

Modélisation statistique pour la prédiction du pronostic de patients atteints d’un Accident Vasculaire Cérébral / Statistical modeling for predicting the prognosis of stroke patients

Ozenne, Brice 23 October 2015 (has links)
L’Accident Vasculaire Cérébral (AVC) est une maladie grave pour laquelle des critères très stricts encadrent l’administration du traitement curatif en phase aigüe. Ces critères limitent drastiquement l’accès à ce traitement : on estime que seuls 10% des patients atteints d’un AVC en bénéficient. L’objectif de ce travail est de proposer un modèle prédictif de l’évolution de l’AVC qui permette d’identifier le volume de tissu à risque de chaque patient. Ce volume, qui correspond au bénéfice potentiel du traitement, permettra de mieux orienter le médecin dans sa décision de traiter. Pour répondre à cet objectif nous nous intéressons aux problématiques d’évaluation de modèles prédictifs dans un contexte de faible prévalence, de modélisation prédictive sur données spatiales, de prédiction volumique en fonction de l’option de traitement et de segmentation d’images en présence d’artefacts. Les outils développés ont été rassemblés au sein d’une librairie de fonctions du logiciel R nommée MRIaggr / Stroke is a serious disease that needs emergency health care. Due to potential side effects, the patients must fulfil very restrictive criteria for eligibility to the curative treatment. These criteria limit drastically the accessibility to treatment : currently, an estimated 10% of stroke patients are treated. The purpose of this work was to develop a statistical framework for stroke predictive models. We deal with assessing predictive models in a low-prevalence context, building predictive models for spatial data, making volumic predictions depending on the treatement option, and performing image segmentation in presence of image artefacts. Tools developed in this thesis have been collected in an R package named MRIaggr
44

Development of a predictive model for research paradigms and philosophies

Mphahlele, Stanford Morore 01 1900 (has links)
Text in English / Although research paradigms and philosophies are highly regarded as frameworks and guides for choices of methods, application thereof is not evident. One of the reasons for the relatively limited application is the complexity and understanding surrounding paradigms and philosophies, making it hard for scholars to determine their stances and implications. This study describes a model for automatically predicting peoples’ paradigm and philosophical stance, including meaning, and their impact on research by helping the user determine the paradigm and philosophical stance closest to their beliefs. Paradigm and philosophical attributes are automatically derived from a set of structured questions that use information matching techniques. The development of a model for Research Paradigm and Philosophy Index (RPPI) follows a two-phase approach. The first phase involves automatic extraction of key indicators from a composed database that utilises an indexing scheme with different philosophies and associated implications. The second phase applies a matchmaking technique that automatically draws information reflecting the user’s attribute. This type of technology exists, but mainly in the dating and career matching fields. None exists for research paradigm and philosophical stances. The prototype system was designed and implemented to serve as a proof of concept, and was developed in Angular, using the Visual Studio Code, and Java, using Eclipse. The database was created using MySQL. The prototype system was designed and implemented to serve as a proof of concept due to the Intellectual Property nature of the product. Usability testing was conducted and results show that the participants agreed the system was simple, straight-forward to use, quite user-friendly and easy to learn, with easy navigation through menu items. / Computer Science / M.Sc. (Computing)
45

Exploring factors that decides on how a Business Intelligence tool is being received by its users

Klaesson, Mårten January 2020 (has links)
Self-Service Business Intelligence (SSBI) is a service where users can create reports andanalyze data on their own. It is an approach to decentralize competence and knowledge withina company. It has been proven to increase productivity and provide employees with morepossibilities to make smart data-driven decisions. I decided to do this project to learn moreabout SSBI and specifically explore what factors that contributes to the user experience ofworking with SSBI. With the help of a survey I was able to reach out to the employees at IfP&C Insurance.I asked how satisfied they were with the SSBI solution at the company, how theyexperienced loading times, how active they were and if SSBI brought value to their day to daywork among many other questions. The data from the survey was analyzed looking at trendsand correlation between answers to identify what parts employees were pleased with and theparts that needs more attention. This was done with the help of Decision Trees, correlationmatrices and extensive graph comparisons. The results managed to answer my scientificquestion rather well. It shows that most employees find that working with SSBI at If P&CInsurance is an enjoyable experience and they believe that it adds real value to their work.There is an interest in further education in Tableau, which is the SSBI software being used atIf P&C Insurance. A fact that shows that employees are eager to learn more, but also that theavailable education at the company has not reached out to all employees. There is also a majorissue with loading times when browsing reports. Users that experiences that loading times areslow or very slow are also overrepresented in the group that is not pleased with the software.The issue with slow loading times has two solutions that I recommend to the company: • Educate employees to create reports that require as low processing power as possibleto browse. This is something that a few employees asked for specifically. • Increase the capacity on their servers. As using Tableau and creating reports hasbecome more and more popular at the company, the servers have not been updated inthe same pace, creating long delays when browsing and working with reports. In general, I think If P&C Insurance has created a functioning environment for SSBI and ifthey address the few issues I have mentioned they will have a thriving Tableau communitywithin the company.
46

Enabling Pro-active Problem Management by Predictive Modelling : Data mining and statistical analysis of past problems to enable pro-active actions for Internet Protocol Television

Dahlin, Anton January 2017 (has links)
Service providers strive to guarantee a certain level of quality of their services, to stay relevant and to keep their customers satisfied and to avoid customer churn. IPTV is such a service. To be able to guarantee quality of service and uptime a good problem management system is vital. Problem management system, are a system of handling occurrences and solutions of all problems and errors. Its primary goal is to detect, prevent and solve errors and incidents, but also prevent reoccurring errors and minimizing the time line of existing problems by finding its root cause. On first contact of a problem there is human operators classifying the problem. Problems with problem management is that it is reactive and problems keep happening. To be able to become pro-active, problems need to be predicted before they occur. This thesis evaluates past problems to enable pro-active actions, by statistics and actionable data mining, using performance data from IPTV service and set top boxes, not utilized today by the company this thesis is carried out for. The result shows that pro-active actions are enabled by adding supervision of the performance data and a packet error ratio. The result also shows that some large problems gets classified too late. By utilizing machine learning and predictive modelling: Logistic regression and Artificial neural network, future disturbance incidents can be predicted. Using disturbance data gave a model accuracy of 80% and 80% respectively with a model Matthew correlation coefficient of 0.50 and 0.56 respectively. Given information of affected active service consumers, if provided, customer impact could easier be assessed. The larger part of this project went to the business understanding, data understanding, data preparation and analysis. By utilizing the unutilized performance data, the problem management system can become more proactive, with the addition of supervision of the IPTV performance data and predictive modelling. / Tjänsteleverantörer strävar att kunna garantera en viss grad av kvalité på de tjänster de erbjuder, för att fortsätta vara relevant, hålla sina kunder nöjda och undvika bortfall av kunder. IPTV är en sådan tjänst. För att kunna garantera en hög tjänstekvalité och hög drifttid, är ett bra problemhanteringssystem viktigt. Problemhanteringssystem är ett system som hanterar förekomsten av och lösningar till alla problem och fel. Dess primära mål är att upptäcka, motverka och lösa incidenter och fel. Även att motverka fortsatt upprepande fel samt att minimera tidslinjen för aktiva fel genom att hitta dess grundorsaken. Vid första kontakt av ett problem så är det mänskliga operatörer som klassificerar problemet. Ett problem med problemhanteringssystem är att de är reaktiva och problem fortsätter att uppkomma. För att kunna bli proaktiv, måste problem kunna predikteras innan de uppkommer. Denna uppsats utvärderar och analyserar gamla problem och incidenter för att möjliggöra proaktivitet, genom statistik och handlingsbar data mining, genom användandet av oanvända prestandadata från IPTV tjänst och digitalbox. Resultat visar att proaktivt agerande möjliggörs genom att lägga till bevakning av prestandadata och en paketfels kvot. Resultat visar även att stora problem blir klassificerad för sent. Genom användandet av maskininlärning och prediktiva modeller: logistisk regression och artificiellt neuralt nätverk, kan kommande incidenter predikteras. Användning av störningsdata gav en modellsäkerhet på 80% och 80% med en Matthew korrelations koefficient på 0.50 och 0.56 respektive. Information om antal aktiva påverkade kunder, om implementerat, hjälper till att bedöma kundpåverkan. Den större delen av detta projekt gick åt till företag förståelse, data förståelse, data förberedning och analys. Men genom användandet av prestandadata, kan problemhanteringssystemet bli proaktiv med tillägget av bevakning av IPTV tjänst och digitalbox data och prediktiv modellering.
47

Our Humanity Exposed : Predictive Modelling in a Legal Context

Greenstein, Stanley January 2017 (has links)
This thesis examines predictive modelling from the legal perspective. Predictive modelling is a technology based on applied statistics, mathematics, machine learning and artificial intelligence that uses algorithms to analyse big data collections, and identify patterns that are invisible to human beings. The accumulated knowledge is incorporated into computer models, which are then used to identify and predict human activity in new circumstances, allowing for the manipulation of human behaviour. Predictive models use big data to represent people. Big data is a term used to describe the large amounts of data produced in the digital environment. It is growing rapidly due mainly to the fact that individuals are spending an increasing portion of their lives within the on-line environment, spurred by the internet and social media. As individuals make use of the on-line environment, they part with information about themselves. This information may concern their actions but may also reveal their personality traits. Predictive modelling is a powerful tool, which private companies are increasingly using to identify business risks and opportunities. They are incorporated into on-line commercial decision-making systems, determining, among other things, the music people listen to, the news feeds they receive, the content people see and whether they will be granted credit. This results in a number of potential harms to the individual, especially in relation to personal autonomy. This thesis examines the harms resulting from predictive modelling, some of which are recognized by traditional law. Using the European legal context as a point of departure, this study ascertains to what extent legal regimes address the use of predictive models and the threats to personal autonomy. In particular, it analyses Article 8 of the European Convention on Human Rights (ECHR) and the forthcoming General Data Protection Regulation (GDPR) adopted by the European Union (EU). Considering the shortcomings of traditional legal instruments, a strategy entitled ‘empowerment’ is suggested. It comprises components of a legal and technical nature, aimed at levelling the playing field between companies and individuals in the commercial setting. Is there a way to strengthen humanity as predictive modelling continues to develop?
48

A FRAMEWORK FOR OPTIMIZING PROCESS PARAMETERS IN POWDER BED FUSION (PBF) PROCESS USING ARTIFICIAL NEURAL NETWORK (ANN)

Mallikharjun Marrey (7037645) 15 August 2019 (has links)
<p>Powder bed fusion (PBF) process is a metal additive manufacturing process, which can build parts with any complexity from a wide range of metallic materials. Research in the PBF process predominantly focuses on the impact of a few parameters on the ultimate properties of the printed part. The lack of a systematic approach to optimizing the process parameters for a better performance of given material results in a sub-optimal process limiting the potentialof the application. This process needs a comprehensive study of all the influential parameters and their impact on the mechanical and microstructural properties of a fabricated part. Furthermore, there is a need to develop a quantitative system for mapping the material properties and process parameters with the ultimate quality of the fabricated part to achieve improvement in the manufacturing cycle as well as the quality of the final part produced by the PBF process. To address the aforementioned challenges, this research proposes a framework to optimize the process for 316L stainless steel material. This framework characterizes the influence of process parameters on the microstructure and mechanical properties of the fabricated part using a series of experiments. These experiments study the significance of process parameters and their variance as well as study the microstructure and mechanical properties of fabricated parts by conducting tensile, impact, hardness, surface roughness, and densification tests, and ultimately obtain the optimum range of parameters. This would result in a more complete understanding of the correlation between process parameters and part quality. Furthermore, the data acquired from the experimentsare employed to develop an intelligent parameter suggestion multi-layer feedforward (FF) backpropagation (BP) artificial neural network (ANN). This network estimates the fabrication time and suggests the parameter setting accordingly to the user/manufacturers desired characteristics of the end-product. Further, research is in progress to evaluate the framework for assemblies and complex part designs and incorporate the results in the network for achieving process repeatability and consistency.</p><br>
49

Evaluation of Nebulas Gold Deposit in Giyani Greenstone Belt, Limpopo Province, South Africa

Mavhungu, Mbofholowo Emmanuel 18 May 2018 (has links)
MESMEG / Department of Mining and Environmental Geology / Giyani Greenstone Belt is known to host significant amount of gold of which about 10 tonnes were extracted from the belt in the 19th century. Due to increased gold price and mining practices that make it economic to mine low-grade ore deposits, major gold deposits within the belt have been the main targets for exploration while Nebulas Prospect remain unnoticed. To make the Nebulas Prospect attractive for investment, its gold mineralization potential needed to be investigated. The main purpose of this study was to conduct assessment of the probable gold mineralization in the Nebulas Prospect and its economic viability. The specific objectives were to establish the gold mineralized zones within the Nebulas Prospect, develop a geological model showing the geometry and placement of gold in the subsurface, establish gold grade distribution and its economic implication, and select the most appropriate and practical mining method for exploitation of the established gold deposit. The research approaches used in achieving these objectives comprised of knowledge driven predictive modelling of Nebulas Prospect to derive prospectivity map demarcating the area with the potential of hosting gold mineralization. Magnetic survey was conducted in geological permissive areas, thereby establishing boundaries of mineralization, both lateral and vertical. Geological and subsurface gold grade distribution were carried out by means of trenching and pitting. The integration of the geological, geophysical and geochemical data using Geosoft 8.5 and ArcGIS 10.5 assisted in development of a gold deposit model that model illustrates distribution and concentration of gold. Results of the investigation reveals that Banded Iron Formation (BIF) dominates the southern part of the study area while quartz vein and schist dominate the northern part. The application of knowledge driven predictive modelling established mineral prospectivity map for Nebulas Prospect, which narrowed the potential area for further investigation. The area located outside the boundary of prospective area indicated low mineralization potential compared to highly mineralized zone within geological permissive boundary. The two mineralize zones which exits in the Nebulas Prospect are separated by pegmatite intrusion which is observed from magnetic data presentation. The gold is hosted within BIF, schist and quartz vein. The highest concentration observed value of 10.65 g/t is hosted in serpentine schist and lowest significant of 1.24 g/t in BIF. The gold grades are higher in schists than in BIF and quartz veins. The Nebulas Prospect present significant measured iv gold mineral resource with substantial economic potential. The evaluation of the technical aspects of the Nebulas Gold Deposit, which include grade and tonnage was estimated through longitudinal vertical section method. The gold hosted within Banded Iron Formation (BIF) comprise a measured gold resource of 6957.6 t at an average weighted grade of 2.22 g/t Au. However, the gold mineralization hosted within tremolite-mica schist, serpentine schist and quartz veins comprise a measured gold resource of 3919.37 t with average grade of 3.8 g/t Au. The Nebulas Gold Deposit contain a significant grade and tonnage. At an assumed currently economically mineable cutoff grade 1 g/t Au, Nebulas Prospect has a measured resource of 10877 t at a weighted average grade of 2.79 g/t Au. Analytical hierarchy process (AHP) was used to prioritize the factors affecting mining method selection and ranking of potential mining method, technically appropriate for the established gold deposit in Nebulas Prospect. Open pit mining method was identified as appropriated for extraction of the Nebulas Gold Deposit. / NRF
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Geographically Weighted Regression based Investigation of Transport Policies for Increased Public Transport Ridership : A Case Study of Stockholm / Utvärdering av transportpolicyer för ökat kollektivtrafikresande baserat på geografiskt viktad regression : En fallstudie för Stockholm

Klar, Robert Günther January 2021 (has links)
Public transport plays a vital role in society as the economy, the degree of sustainability and the qualityof life of a city is directly affected by transportation. A shift in modal share towards public transport isassociated with many benefits such as increased air quality and improved space allocation within thecity. To further promote public transport, an appropriate measure of competitiveness is required toevaluate the impact of past and future transport policies. This study introduces the journeys per capitaratio as a new way of measuring public transport competitiveness. Firstly, the key factors affecting thepublic transportation usage rate expressed as the journeys per capita ratio are identified to evaluatethe impact of public transport provider efforts. For this purpose, data for a total of 32 explanatoryvariables and a scope of 218 regions for seven consecutive time frames are collected. Secondly,geographically weighted regression (GWR) – a local regression-based spatial analysis technique – isperformed to test if the journeys per capita ratio is a suitable target variable to predict the impact ofcertain transport supply changes. A traditional global ordinary least square (OLS) model is conductedas well to compare if a local model could be more beneficial. The GWR and the OLS model are trainedwith the data of previous years and tested with data from the consecutive following years. Thirdly,further temporal and socio-economic based cluster analyses are performed to assess the validity andthe explanatory power of the journeys per capita ratio. The conducted analyses reveal that thejourneys per capita ratio is a superior measure for assessing public transport competitiveness.Goodness of fit statistics and estimation results demonstrate that the GWR model has betterprediction accuracy and is more capable of retrospectively predicting the impact of previous transportpolicies. / Kollektivtrafiken har en avgörande roll i samhället då ekonomin, graden av hållbarhet och städerslivskvalité är direkt påverkad av transport. En förändring av transportanvändning från bil motkollektivtrafik är förknippad med flera fördelar, såsom ökad luftkvalitet och förbättrad rumsligallokering inom staden. För att ytterligare främja kollektivtrafik krävs ett lämpligt mått påkonkurrenskraft för att utvärdera effekterna av tidigare och framtida transportpolitik. Den här studienintroducerar resor per capita-förhållanden som ett nytt sätt att mäta kollektivtransportenskonkurrenskraft. För det första identifieras nyckelfaktorerna som påverkar användningsgraden förkollektivtrafik, uttryckt som förhållandet resor per capita för att utvärdera effekten avkollektivtrafikleverantörens insatser. För det här syftet har data för totalt 32 variabler och ett omfångav 218 regioner under sju, på varandra, följande tidsramar har samlats in. För det andra har Geografisktviktad regression (GWR), vilket är en lokal regressionsbaserad rumslig analysteknik, använts för atttesta om resor per capita-förhållanden är en lämplig målvariabel för att förutsäga effekterna av vissatransportförändringar. En traditionell Global ordinary least square model (OLS) har också använts föratt jämföra om en lokal modell är mer fördelaktig. GWR och OLS modellerna har tränats med data fråntidigare år och testats med data från följande år. För det tredje har ytterligare tidsmässigsocioekonomisk baserad klusteranalys utförts för att bedöma validiteten och förklaringsförmågan förresornas förhållande per capita. De genomförda analyserna pekar på att förhållandet resor per capitaär ett fördelaktigt mått för att bedöma kollektivtrafikens konkurrenskraft. Goodness of fit statistics ochde uppskattade resultaten visar att GWR-modellen har en bättre förmåga att göra noggrannaförutsägelser och är mer kapabel att i efterhand förutsäga effekterna av tidigare transportpolitik.

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