Dissertations / Theses on the topic 'Stance mining'

Nell'ultimo decennio i settori di ricerca nell'ambito dell'elaborazione automatica del linguaggio naturale (NLP) hanno acquisito sempre maggiore interesse, in concomitanza con l'introduzione continua di strumenti di machine learning innovativi. In generale, seppur sia comunque presente un'ambizione ideologica, l'interesse principale è riconducibile ad un piano prettamente applicativo, di natura sociale o politica, dove l'introduzione di nuove informazioni può apportare un notevole miglioramento in molti processi di interesse reale e contribuire all'indagine di nuove tendenze e/o conflitti. Il potenziale riscontrato nei presenti ambiti di ricerca ha attirato l'attenzione di aziende di notevole portata, al punto da finanziare progetti ambiziosi volti a rispondere a necessità emergenti proprie di molteplici realtà di diversa natura. A partire da queste premesse, il presente elaborato si pone come obiettivo la definizione di un modello atto a individuare punti di affinità tra due specifiche attività di recente interesse, denominate stance classification e argument structure prediction. I primi due capitoli introducono rispettivamente i concetti di stance classification e argumentation mining, soffermandosi, in particolar modo, sulle tecniche e le metodologie impiegate. Il terzo capitolo affronta il tema della definizione di uno strumento di classificazione comparabile con lo stato dell'arte nell'ambito della stance classification. Il quarto capitolo si interessa principalmente dell'individuazione di un legame tra i due settori di ricerca presi in esame, per poi mettere a confronto alcune tecniche specifiche attualmente impiegate per l'argument structure prediction con le principali adottate nell'ambito della stance classification. Infine, nel quinto e ultimo capitolo viene proposto un nuovo corpus per la sperimentazione degli stessi approcci impiegati nel capitolo precedente, con particolare attenzione a proporre degli opportuni test di confronto e di verifica.

Philosophiae Doctor - PhD
The Sandamap gold prospect is a metaturbidite shear zone-hosted gold mineralization located in the Neoproterozoic Damara Orogen 30 km northwest of the town of Usakos in Namibia with an estimated gold content of 240 000 t at 3.6 g/t up to 40 m below surface. This research project was aimed at constraining the age, crustal level of formation, pressure-temperature conditions during formation, sources of the mineralizing fluids, and by implication, the metal sources of the Sandamap gold mineralization. Fluid inclusion, geochronological and isotopic studies were carried out on quartz veins hosting the ore. The presence of kaolinite, alunite and jarosite suggest post-hydrothermal weathering of sulfides. Various sources of data from this study, giving rise to depths of entrapment of 4 to 14 km, temperature range of entrapment of fluids of 187 – 594 °C, stable isotope data (δ13C and δ18O), δD values and a δD vs. δ18OH2O plot are all in favour of an orogenic gold deposit. Additionally, the dominant CO2-rich and CH4-rich fluids observed at Sandamap do not contradict this interpretation. The calculated depth of entrapment of mineralization covers the lower portion of the epizonal zone to the upper portion of the hypozonal zone of gold deposits. The Sandamap mineralization’s δD values of -35‰ to -49‰ fall within the range of most published data for typical orogenic gold deposits which varies from -20 to -80‰. Moreover, the calculated δ18Owater values of the ore-fluids (+6.6 to +11.3‰) of the higher temperature aqueous group from the Sandamap mineralization fall within the range observed in typical orogenic gold deposits found in Phanerozoic terrains (+7 to +13‰). The schist hosting the mineralized shear zone with a gold content of 0.05 ppm Au or its higher grade equivalent at depth, is a possible gold source candidate. Two mechanisms of deposition were possibly at play: (i) the cooling below 500 °C and possible sulfidation (resulting from fluid-rock interaction), lowered the solubility of pyrite causing S3- and Au(HS)S3- (possible main Au carriers) to breakdown resulting in decreased Au solubility and its subsequent deposition and (ii) the elevated amount of CO2 (e.g. trench 14 where CO2-rich fluid inclusions are dominant) led to a sharp decrease in the Au(HS)2- and Au(HS)S3- concentrations, causing decreased Au solubility and its subsequent deposition. The age of mineralization obtained from 40Ar/39Ar dating of the muscovite associated with the ore-hosting quartz veins is placed at 472 ± 3 Ma. The mineralization is younger than the shear zone, which acted as a conduit for ore-fluid migration and it has no age relationship with proximal plutonic bodies. The mineralization is younger than the foliated granite (FG), which exhibits a metamorphic fabric in the form of mineral segregation, but older than the non-foliated granite (GT) which hosts a mineralized xenolith.

Sulfate, nitrate, and certain trace elements are common groundwater contaminants observed at mining sites. Their source, fate, and remediation were investigated at a former uranium mining site. First, groundwater samples collected across the site were analyzed for geochemistry, stable isotopes, and trace elements. Then, two pilot-scale ethanol injection tests were conducted for biostimulation of nitrate and sulfate reduction. Groundwater was monitored in the test area before and after the tests. The results showed a mixing of two discrete sources of sulfate. Quantification of these two sources using two methods showed that sulfide-mineral oxidation of the mine tailings served as a steady but low-discharge source while sulfuric acid (applied during ore processing in the 1960s) served as a variable, strong source. It appears that sulfuric acid served as a sustained source of sulfate for approximately 40 years. This source may be from accumulation of sulfate salts (formed from sulfuric acid) in the source zone due to the arid climate of the site. Results showing correspondence of isotopic compositions of ammonium and nitrate confirmed the generation of nitrate via nitrification. Moreover, it was observed that ammonium concentration is closely related to concentrations of uranium and a series of other trace elements including chromium, selenium, vanadium, iron, and manganese. It is hypothesized that ammonium-nitrate transformation processes influence the disposition of the trace elements through mediation of redox potential, pH, and possibly aqueous complexation and solid-phase sorption. As for the biostimulation, sulfate reduction condition has been maintained for a period of approximately 3 years after a single input. Atypical fractionation behavior of the delta34S in sulfate was hypothesized to be caused by release of sulfate from sulfate minerals associated with the sediments. Elevated hydrogen sulfide concentrations were not observed until approximately four months after the start of the test. This behavior, in concert with the observed changes in aqueous iron and manganese species, suggests that hydrogen sulfide produced from sulfate reduction was precipitated, presumably in the form of iron sulfides, until the exhaustion of readily reducible iron oxides. Hydrogen sulfide produced thereafter appears to have been in part re-oxidized.

This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the electronic waveform generator, and the RF carrier frequency is limited by the bandwidth of the photodetector. Similarly, using parabolic phase modulation together with time division multiplexing, RF chirp extension has been realized. Another application of the optical frequency combs studied in this thesis is real time data mining in a bit stream. A novel optoelectronic logic gate has been developed for this application and used to detect an 8 bit long target pattern. Also another approach based on orthogonal Hadamard codes have been proposed and explained in detail. Also novel intracavity modulation schemes have been investigated and applied for various applications such as a) improving rational harmonic modelocking for repetition rate multiplication and pulse to pulse amplitude equalization, b) frequency skewed pulse generation for ranging and c) intracavity active phase modulation in amplitude modulated modelocked lasers for supermode noise spur suppression and integrated jitter reduction. The thesis concludes with comments on the future work and next steps to improve some of the results presented in this work.
Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD

In many ore deposits throughout the world, brecciation often accompanies or occurs in association with mineralization (Sillitoe, 1985). Such is the case in the Tintic Mining District (Ag-Pb-Zn) of north-central Utah, where unique breccia features called pebble dikes occur alongside significant mineralization. Pebble dikes are tabular bodies of breccia, which consist of angular to rounded clasts of quartzite, shale, carbonate, and minor igneous rock cemented in a fine-grained clastic matrix. All clasts now lie above or adjacent to corresponding source rocks. Dikes are thin, typically less than 0.3 m wide to as much as 1 m, and can exceed 100 m in length. The average of the largest clast sizes is less than 3 cm but correlates positively with pebble dike width. Contacts are sharp and an envelope of fine breccia surrounds roughly half of the dikes. Pebble dikes are mostly hosted in an Eocene rhyolite lava flow, which displays argillic to silicic alteration when in contact with a pebble dike, but are also hosted in an assortment of folded Paleozoic sedimentary rocks. The dikes show a strong northeast trend in orientation, following a regional fabric of northeast-trending strike-slip and oblique-slip faults.The formation of pebble dikes has been historically attributed to the intrusion of the Silver City Stock, the Tintic District's main productive intrusion (Morris and Lovering, 1979; Hildreth and Hannah, 1996; Kim, 1997; Krahulec and Briggs, 2006). However, pebble dikes are spatially associated with a previously unrecognized porphyritic unit, informally named the porphyry of North Lily, which is texturally, mineralogically, and chemically distinct from the Silver City Stock, and like pebble dikes, is emplaced in northeast-trending plugs and dikes. Pebble dikes show a strong spatial correlation to outcrops of the porphyry of North Lily. Additionally, clasts of the porphyry of North Lily have been found in pebble dikes, while pebble dike quartzite clasts have been found as xenoliths in the porphyry of North Lily. These similarities and interactions suggest simultaneous formation. Low-grade alteration associated with pebble dikes indicates that they formed at elevated temperatures (<150°C). Stable isotope characteristics of rhyolite altered during the emplacement of pebble dikes suggests that the dikes formed in the presence of heated groundwater, with little to no magmatic water association. The overall physical, spatial, and chemical characteristics of pebble dikes of the Tintic Mining District suggest that they formed by the mobilization of breccia in the explosive escape of groundwater that had been heated by the porphyry of North Lily. This escape occurred along pre-existing northeast-trending faults and fractures. Pebble dikes then became pathways for later ore fluids, easing the creation of the district's abundant mineral resources.

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Em regiões áridas e semiáridas, a água superficial não está disponível de forma perene, e as águas subterrâneas proporcionam, na maioria dos casos, a única fonte de água permanente e segura. Esta situação é particularmente verdadeira na Bacia Experimental Caetité (BEC), localizada na região semiárida do Nordeste do Brasil, onde a comunidade local é fortemente dependente da disponibilidade de águas subterrâneas. A questão da água se agravou em 1999, com o início das operações de uma instalação nuclear, a Unidade de Concentrado de Urânio (URA), e a comunidade local teve que enfrentar não apenas os desafios associados à escassez de água, mas também os potenciais processos de contaminação decorrentes da atividade de mineração. Este cenário provocou um debate crescente entre a comunidade local e o centro de produção de urânio. Embora vários estudos venham sendo conduzidos na região, o regime de fluxo de águas subterrâneas nesta bacia hidrográfica permanece mal compreendido. Este estudo tem como objetivo investigar a dinâmica das águas subterrâneas e mecanismos de recarga nesta bacia, como parte dos esforços iniciais para caracterizar a hidrogeologia desta área afim de subsidiar futuros estudos de contaminação. Medidas de δ2H, δ 18O, total de sólidos dissolvidos (TSD), pH e condutividade elétrica (EC) foram realizadas em um total de 181 amostras (122 águas subterrâneas, 36 águas superficiais e 23 amostras de precipitação) coletadas durante as estações secas e chuvosas de 2012 a 2014. Os resultados químicos, físico-químicos e isotópicos sugerem que a recarga é espacialmente variável, correndo por mecanismo direto e indireto, por precipitação local e contribuição da água superficial, respectivamente. Estes resultados apontam para uma dinâmica rápida deste sistema, tornando-o mais vulnerável à contaminação por atividades na superfície do terreno, uma vez que os contaminantes podem rapidamente atingir o aquífero.
In arid and semi-arid regions, where surface water is not available on fixed basis, groundwater provides in most cases the only permanent and safe source of water. This situation is particularly true in the Caetité Experimental Basin (CEB), located in the semi-arid region of Northeastern Brazil, where the local community depends heavily on groundwater availability. The water issue has been aggravated since 1999 when a nuclear facility, the Uranium Concentrate Unit (URA), started operations and the local community had to face not only the challenges associated with water scarcity but also the potential contamination processes due to mining activity. This scenario caused an increasing debate over competing water interests between the local community and the uranium production center. Although several studies have been conducted to characterize the hydrological system of the region, the groundwater flow regime in this watershed remains poorly understood. This study aims to investigate the groundwater dynamics and recharge mechanisms in this basin, as part of initial efforts to characterize the hydrogeology of this area for future contamination studies. Measurements of δ2H, δ18O, total dissolved solids (TDS), pH, and electrical conductivity (EC) were carried out in a total of 181 samples (122 groundwater, 36 surface water and 23 rainfall samples), collected during the dry and wet seasons from 2012 to 2014. The chemical, physicochemical and Isotope results suggest that the recharge is spatially variable, occurring by direct and indirect mechanism, by local precipitation and surface water contribution, respectively. These results point to a fast dynamic of this system, which makes this aquifer more vulnerable to contamination from activities in the land surface, as the contaminants could move and quickly reach the aquifer.

The Internet provided humans a new way to exchange information digitally and has changed how we communicate. Blockchain and cryptocurrencies have given humans a new way to exchange value over the internet. With new technology, new possibilities arise, but not always without issues. One problem that has risen with cryptocurrencies is their high volatility, meaning that the currency has big price swings. It has made these currencies objects for speculation and investment almost exclusively, and therefore they have lost their functionality as a currency. For a currency to be viewed as a good means of payment, it cannot be associated with high volatility. This is not only restricted to cryptocurrencies, as for example the Venezuelan Bolivar is a fiat currency with historically high volatility and has been losing its purchasing power due to hyperinflation in the recent years. In regard to this we propose a new cryptocurrency; the Dynamic Network Token, which aims to reduce the volatility in a cryptocurrency by regulating the supply dynamically with burning and minting. The implementation of this functionality will strive to remove the high volatility in the token for the benefits of a more stable and linear growth, and at the same time encourage users to transact with the Dynamic Network Token between each other.
Internet gav människor möjlighet att utbyta information digitalt och har förändrat hur vi kommunicerar. Blockkedjeteknik och kryptovalutor har gett människan ett nytt sätt att utbyta värde på internet. Med ny teknologi kommer möjligheter, men kan även medföra problem. Ett problem som uppstått med kryptovalutor är deras volatilitet, vilket betyder att valutan upplever stora prissvängningar. Detta har gjort dessa valutor till objekt för spekulation och investering, och därmed gått ifrån sin funktion som valuta. För att en valuta ska anses som ett bra betalmedel, bör den inte ha hög volatilitet. Detta är inte bara begränsat till kryptovalutor, då till exempel Venezuelas nationella valuta Bolivar är en fiatvaluta med historiskt hög volatilitet som förlorat sin köpkraft på grund av hyperinflation under de senaste åren. Med detta i åtanke föreslår vi en ny kryptovaluta; Dynamic Network Token, vars uppgift är att reducera volatiliteten i en kryptovaluta genom att reglera utbudet dynamiskt med hjälp av burning och minting. Denna implementeringsuppgift är att minska hög volatilitet till fördel för en mer stabil och linjär tillväxt och samtidigt uppmana användare att använda Dynamic Network Token mellan varandra i nätverket.

The Alnö Complex is a Late Precambrian alkaline and carbonatite intrusion (c. 30km2) into Early Proterozoic country rock that extends from the north east, to the north western shoulder of Alnö Island. Carbonatites are rare among volcanic provinces, with Oldoinyo Lengai of northern Tanzania being the only active carbonatite volcano in the world today. The high carbonate mineral volumes and rare earth element (REE) concentrations of carbonatites, in combination with the intrusive-extrusive nature of their suites contribute to the rarity of these rocks. Carbonatites, through their peculiar petrological and geochemical compositions, provide vital insights to the composition and condition of the Earth’s mantle. The genesis of the Alnö carbonatites and their relation to other lithological units at the complex is however, only partially understood. This stems from the epistemological division of carbonatites as having either a ‘magmatic’ or ‘reactive’ origin. This study focuses on sampled carbonatites from the Alnö Complex, employing an oxygen and carbon isotope approach on their native calcite, complemented with petrological and mineralogical methods in order to constrain petrogenesis. As a reference, oxygen and carbon isotope data of calcite from an earlier Alnö investigation as well as from an array of data from comparative alkaline complexes elsewhere are also discussed. The combined data and the derived findings support a scenario that is consistent with the ‘magmatic’ model wherein carbonatites have a primary mantle-derived origin, and prospectively stem from a parent magma akin to that of Oldoinyo Lengai, but have experienced a degree of silicate and sedimentary assimilation. The extraction of the Alnö carbonatites for their rare earth metals is a looming possibility due to the current volatility in the rare earth market. The risks and opportunities involved in this kind of natural resource extraction provide a context wherein sustainable development paradigms can be applied. The capacity of the Alnö environment to withstand the impact of development in the mining sector is discussed through a perspective of establishing a quarry, and quarry-related methods for rare earth extraction.

Orientadores: Lena Virginia Soares Monteiro, Roberto Perez Xavier
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Localizados na porção norte da Província Mineral de Carajás, a uma distância de cerca de 8 km do depósito de óxido de ferro-cobre-ouro de Sossego, estão os depósitos de cobre Alvo Bacaba e Alvo Castanha. Esses depósitos encontram-se ao longo de uma zona de cizalhamento regional de cerca de 60 km de extensão, no limite entre o Supergrupo Itacaúnas e seu embasamento representados principalmente pelos migmatitos do complexo Xingu. O Alvo Bacaba é hospedado pelo granito Serra Dourada e pelo tonalito Bacaba, enquanto o Alvo Castanha é Ambos os depósitos exibem amplas zonas de alteração hidrotermal que compreendem quase que respectivamente a albitização, a escapolitização, a formação de óxidos de ferro, a alteração sódico-cálcica, a alteração potássica, a formação de turmalina, a sericitização, a cloritização, a epidotização e a carbonatização, embora estes depósitos mostrem diferenças, como a alteração sódico-cálcica que apesar de ser bem desenvolvida no Alvo Castanha, é quase inexistente no Alvo Bacaba, onde apenas ocorre como alteração nos gabros. Também o Alvo Bacaba possui uma associação de minerais distintas, composta por calcopirita±pirita±bornita, enquanto o Alvo Castanha exibe a associação calcopirita±pirrotita±pirita. Informações sobre evolução paragenética e dados de isótopos estáveis indicam que os depósitos Alvo Bacaba e Alvo Castanha evoluíram durante progressivo resfriamento. Entretanto, esta redução com relação à evolução paragenética foi maior no Alvo Bacaba do que no Alvo Castanha, e a fugacidade de oxigênio foi mantida alta no Alvo Bacaba. A temperatura de deposição do minério estimada para o Alvo Bacaba pode ter ocorrido entre 220 °C e 410 °C, enquanto no Alvo Castanha esta teria ocorrido entre 350 °C e 420 °C. A evolução isotópica do Alvo Bacaba é similar àquela caracterizada para o depósito de Sossego, com uma redução acentuada da temperatura acompanhada por um decréscimo no valor de ?18O e acréscimo no valor de ?D e evidências de misturas de fluido juvenil e de fonte não magmática. Já para o Alvo Castanha, as composições isotópicas dos fluidos hidrotermais indicam a predominância de uma fonte magmática. Estas características e similaridades com aquelas de Sossego podem apontar para uma contribuição de águas magmáticas e oceânicas no sistema hidrotermal que originou todos estes depósitos
Abstract: The Alvo Bacaba and Alvo Castanha copper deposits are located at the northern part of the Carajás Mineral Province, at a distant radius of about 8 km from the Sossego iron oxide-copper-gold deposit. These deposits occur along a regional shear zone 60 km wide, in the limit between the Itacaiúnas Supergroup and its basement represented mainly by migmatites of the Xingu Complex. Both deposits exhibits widespread hydrothermal alteration zones comprising albitization, scapolitization, iron oxide formation, sodic-calcic alteration, potassic alteration, tourmaline formation, sericitization, epidotization and carbonatization, although these two deposits show differences like sodic-calcic alteration, which is well developed in Alvo Castanha, but it is almost inexistant in Alvo Bacaba, being present only in its altered gabbros. Also the Alvo Bacaba shows ore minerals association essencialy composed by chalcopyrite±pyrite±bornite while the Alvo Castanha shows the association of chalcopyrite±pyrrhotite±pyrite. Paragenesis and stable isotope data indicate that the Alvo Bacaba and Alvo Castanha deposits have evolved with temperature decrease. However, the temperature drop in relation to the hydrothermal alteration succession was greater in Alvo Bacaba than the Alvo Castanha, and the oxygen fugacity was kept higher at Alvo Bacaba. The estimated temperature for ore deposition in the Alvo Bacaba was between 220 °C and 410 °C, while the Alvo Castanha it would have occurred between 350 °C and 420 °C. The isotopic evolution of the Alvo Bacaba is similar to that characterized for the Sossego deposit, with a steep temperature reduction accompanied by decrease of ?18O and increase of ?D values and fluid mixing evidences. In the Alvo Castanha, isotopic compositions of the hydrothermal fluids indicate predominance of magmatic sources. These characteristics and its similarities with those of the Sossego deposit could point to a contribution of magmatic and ocean waters in the hydrothermal system that originated all deposits
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências

Video acquired using a camera mounted on a mini Unmanned Air Vehicle (mUAV) may be very helpful in Wilderness Search and Rescue and many other applications but is commonly plagued with limited spatial and temporal field of views, distractive jittery motions, disorienting rotations, and noisy and distorted images. These problems collectively make it very difficult for human viewers to identify objects of interest as well as infer correct orientations throughout the video. In order to expand the temporal and spatial field of view, stabilize, and better orient users of noisy and distorted mUAV video, a method is proposed of estimating in software and in real time the relative motions of each frame to the next by tracking a small subset of features within each frame to the next. Using these relative motions, a local Euclidean mosaic of the video can be created and a curve can be fit to the video's accumulative motion path to stabilize the presentations of both the video and the local Euclidean mosaic. The increase in users' abilities to perform common search-and-rescue tasks of identifying objects of interest throughout the stabilized and locally mosaiced mUAV video is then evaluated. Finally, a discussion of remaining limitations is presented along with some possibilities for future work.

碩士
國立東華大學
應用數學研究所
86
The minima-stable model, proposed earlier by Klebanev, Rachev, andYakovlev [6] substantiates the employment of minima-stable distributionson the latent time distribution at high dose values.A two dimensional generalization of such model appears in the form ofthe Weibull-Marshall-Olkin and Pareto-Marshall-Olkin distributionsderived by Rachev, Wu, and Yakovlev [12]. In the present paper, wediscuss the statics of bivariate Weibull-Marshall-Olkin and bivariate Pareto-Marshall-Olkin distributions and the relation between them.An example for the fitting of tumor latency time to the Weibull and Pareto distributions is given. These distribution provide a good descriptions of some published experimental data on radiation-inducedcarcinogenesis.