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1
Larouche, Pascal. "Minor elements in copper smelting and electrorefining". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33978.
Testo completoAbstract (sommario):
Minor element (As, Sb, Bi, Pb, Ni) behavior, control and removal techniques in the conventional copper smelting/electrorefining process was studied. The analysis was based on the information collected from an exhaustive literature review, the visit of 23 smelters, 14 electrorefineries and consultations at 15 different institutes specialized in the field.Data was collected for several types of matte smelting furnaces such as Outokumpu flash, INCO flash, Mitsubishi S-furnace, Teniente Converter, Noranda Process Reactor, Isasmelt and reverberatory. Behavior in Peirce-Smith converting furnaces, Mitsubishi C-furnace, Noranda Continuous Converter and Kennecott-Outokumpu Flash Converting Furnace was also discussed.
The effect of various matte smelting furnace operating parameters such as matte grade, oxygen enrichment, concentration in feed, other minor constituents and temperature on minor element partition to gas and distribution coefficient (wt% matte/wt% slag) was analyzed theoretically and validated with industrial data when possible. Because fewer data were available, only a brief comparison between the elimination in traditional batch converting and new continuous converting processes was performed. The behavior of minor elements in electrorefining was described from a theoretical viewpoint. (Abstract shortened by UMI.)
2
Luganova-Chnyrenkova, Tatiana. "Factors affecting behaviour of minor elements in dore metal-soda slag partitioning". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26404.
Testo completoAbstract (sommario):
A series of experiments determined the influence of oxygen partial pressure and SiO$ sb2$ content in soda slag on the distribution of metals between soda slag and dore metal. Oxygen partial pressure ranged from 10$ sp{-8}$ to one atmosphere and the SiO$ sb2$ content from 0 to 10 wt%.Minor elements, including the precious metals, partition between the dore metal and the soda slag. The main purpose of this research was to determine the process parameters which influence this distribution, and the nature and forms of the precious metals in the metal and in the slag phases.
From the results of the experiments it was found that: (a) Increasing oxygen partial pressure from 10$ sp{-8}$ to 1 atm does not influence gold, palladium and platinum removal from dore metal, but leads to the practically complete removal of Te (down to 4.8 ppm), Rh (down to 2.7 ppm), Pb (down to 6.0 ppm) and quite good removal of Se (down to 0.0112 wt%) and Cu (down to 0.42 wt%) from the dore metal. (b) Silica content of the soda slag does not influence gold, palladium and platinum chemical losses with soda slag. However it was found that increasing silica in slag leads to an increase of mechanical loss of precious metals because of the increase in slag viscosity. (c) Increase in silica content of slag increased lead and copper removal from dore metal, and decreased the removal of rhodium, selenium and tellurium, especially at low oxygen potential. (d) It was concluded that most of precious metals leave dore metal in the form of mechanical losses, but silver and rhodium were found in slags as intermetallic phases with the other components. Rhodium is also lost in the form of the volatile oxide RhO$ sb2$. (Abstract shortened by UMI.)
3
Lee, Rena J. "Study of trace and minor elements in ALS (amyotrophic lateral sclerosis) patients". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36492.
Testo completo
4
Du, Toit Adam Jacobus. "Thermodynamic behaviour of sulphur and chlorine as minor elements in metallurgical melts". Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/5379.
Testo completoAbstract (sommario):
Includes bibliographical references (p. 137-147)This thesis is presented on the equilibrium studies that have been carried out on a series of slags, specifically chosen to cover the range of composition and conditions appropriate to the melters of the platinum group metals (PGM) producers of South Africa. New measurements have been made on the ferric to ferrous ration, sulphide capacity as well as the chloride capacity mainly for the PGM melter-type slags.
5
Cao, Qianwen. "Mass Balance of Major, Minor and Trace Elements During AFBC Combustion of Fuels". TopSCHOLAR®, 1997. http://digitalcommons.wku.edu/theses/899.
Testo completoAbstract (sommario):
The proposed ASTM procedures for the determination of 13 major and minor., and 11 trace elements, in solid coal and coke combustion residues by inductively coupled plasma-atomic emission spectrometry (ICP-AES) were checked for routine use. In this study, the ICP analysis values and XRF analysis values of major and minor elements in two kinds of coal and two kinds of limestone were compared. It was shown that over 95% closure of the mass balances of the 24 major, minor, and trace elements was obtained with the proposed ASTM procedure. Also, it was demonstrated that trace elements may be lost through combustion. From six combustion runs, the composition of the fly ashes produced in the FBC burns was determined by XRF analysis. The total carbon, inorganic carbon, and unburned carbon in the fly ashes were also determined. The combustion efficiency of the AFBC system was calculated by comparing the carbonto-iron ratios in the unburned fuel to that in the fly ashes.
6
COSTA, ISOLDA. "Effect of minor addition elements on the corrosion behaviour of bare and coated steels". reponame:Repositório Institucional do IPEN, 1991. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10281.
Testo completoAbstract (sommario):
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Tese (Doutoramento)
IPEN/T
University of Manchester, England
7
Anttila, S. (Severi). "Influence of minor elements on some weldability issues of intermediate purity stabilized ferritic stainless steels". Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526219738.
Testo completoAbstract (sommario):
Abstract Stabilized ferritic stainless steel grades are attractive alternatives to common austenitic grades in sheet metal applications. Compared with older unstabilized ferritic grades, the mechanical and corrosion properties are usually improved. The impurity level, mainly the amount of interstitial carbon and nitrogen, plays an important role in these steels. There are notable issues in the welding of these steels, the most apparent difference to austenitic steels is the susceptibility to brittle failure. This research focused on the influence of minor elements, especially aluminium, calcium, silicon, titanium, niobium, nitrogen and oxygen, on the weldability of modern intermediate purity level stabilized ferritic stainless steels. The research proceeded in several stages. At first, the general characteristics and performance data about the welds in currently manufactured 11 to 21 mass percent chromium ferritic stainless steels in Europe was obtained. The research then focused on novel high chromium stabilized ferritic stainless steels. Lastly, the influence of various steelmaking practices on weldability were investigated. The results showed that in stabilized ferritic stainless steels, slag islands are frequently seen in the molten weld pools. These islands can have many origins, e.g. deoxidation, calcium treatment and stabilization practices, and they can be roughly assessed from the chemical composition of the steel. The nature and the influence of these slags varies and can be related to irregularities in the weldability and molten metal fluid flow. Large grain size and titanium carbonitride particles impair the toughness of the heat-affected zone. Generally, stabilization with niobium is preferred. However, solely niobium stabilized steel welds run the risk of forming coarse columnar grains in welds deteriorating some of the properties. A breakdown of the columnar grains is possible to achieve in autogenous welds with minor titanium and aluminium alloying, provided that small amounts of nitrogen and oxygen are induced from the shielding gas. However, grain refinement may not improve the properties, if it is accomplished with an increase in the total interstitial contentTiivistelmä Stabiloidut ferriittiset ruostumattomat teräkset soveltuvat korvaamaan tavanomaisia austeniittisia ruostumattomia teräksiä ohutlevysovelluksissa. Näillä teräksillä keskeiset mekaaniset ja korroosio-ominaisuudet ovat usein paremmat kuin varhaisilla, stabiloimattomilla ferriittisillä teräksillä. Hiili ja typpi ovat näissä teräksissä kuitenkin epäpuhtauksia. Toisin kuin austeniittiset teräkset, ferriittiset teräkset ovat alttiita haurasmurtumalle, erityisesti hitsatuissa rakenteissa. Tässä väitöstutkimuksessa keskityttiin mikroseosaineiden ja epäpuhtauksien vaikutukseen keskipuhtaiden stabiloitujen ferriittisten teräslajien hitsauksessa. Tutkimus kohdistui erityisesti alumiinin, kalsiumin, piin, titaanin, niobin, typen ja hapen vaikutuksiin. Aluksi tutkittiin kaupallisten terästen hitsien keskeisiä ominaisuuksia. Tämän jälkeen tutkittiin uusia ns. korkeakromisia stabiloituja ferriittisiä teräslajeja. Lopuksi tutkittiin teräksen valmistuksen vaikutuksia stabiloitujen ferriittisten ruostumattomien terästen hitsattavuuteen. Tutkituilla teräksillä hitsauksen aikana muodostui runsaasti kuonalauttoja. Näillä kuonilla on monta alkuperää, esim. deoksidointi, kalsiumkäsittely ja stabilointiaineet. Hitsien kuonaisuutta voidaan karkeasti arvioida teräksen kemiallisen koostumuksen perusteella. Muodostuvilla kuonilla on useita vaikutuksia hitsauksessa, mm. epäjatkuvuuksiin ja sulan virtauksiin. Hitsauksessa muodostuva suuri raekoko ja stabiloinnin titaanikarbonitridipartikkelit heikentävät oleellisesti hitsin muutosvyöhykkeen sitkeyttä. Stabilointi käyttäen pääasiassa niobia on toivottavaa, mutta jos stabilointiin käytetään vain niobia, tulee hitsin mikrorakenteesta karkea ja hitsin ominaisuudet voivat heikentyä. Karkean mikrorakenteen hienontaminen on mahdollista käyttäen suojakaasuna argonia, jossa on hieman typpeä ja happea, mikäli teräkseen on seostettu hieman alumiinia ja titaania. Raerakenteen hienontaminen ei kuitenkaan yksiselitteisesti paranna hitsin ominaisuuksia, mikäli hienontaminen saavutetaan kasvattamalla epäpuhtauspitoisuutta tarpeettoman korkeaksi
8
Stewart, Andrew John. "Planetary cores : effect and behaviour of minor elements on the Fe-S system to 40 GPa /". Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16815.
Testo completo
9
Laban, Kay. "The development and application of methods for investigating the distribution of minor and trace elements in coal". Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287238.
Testo completo
10
Chi, Xiaoliu. "Development of Methods for the Determination of Major and Minor Elements and Hydrocarbon Residues in Solid Combustion Products". TopSCHOLAR®, 1997. http://digitalcommons.wku.edu/theses/772.
Testo completoAbstract (sommario):
Methods for the determination of inorganic constituents in coal fly ash by glow discharge spectrometry (GDS) and for the extraction of the organic compounds from coal and ash by supercritical fluid extraction (SFE) at temperatures below 150°C are reviewed. The inorganic elements studied included Al, Ca, C, Cu, Fe, Mg, Mn, P, S, Si and Ti. The organic compounds were measured by weight loss of the sample. The goal of this research was to find easier and faster ways to measure the concentration of inorganic elements in coal ash and to measure extractability of the coal itself, to make coal conversion and utilization more efficient and convenient. The results of this research indicated that for inorganic element determination, graphite can be used as the host material to make the coal ash pellets. When 90% graphite and 10% ash were mixed together and compressed under 20 tons of pressure, the pellets had suitable conductivity and mechanical strength, and the calibration curves for most of the elements were linear, especially for Al and Si. Copper was also used as the host material. In copper pellets the intensities of all elements were much larger than those in graphite, indicating that copper is more promising for pellet preparation. For supercritical fluid extraction, temperature is an important factor for extraction efficiency. The pressure and kinds of modifiers used were also important for extraction. The weight loss by supercritical fluid extraction of coal was much smaller than by soxhlet extraction, indicating that it is difficult to extract organic compounds from coal by SFE at temperatures below 150°C.
11
Gumbmann, Eva Maria. "The effect of minor alloying elements (Mg, Ag, Zn) on the nucleation and precipitation behaviour in AlCuLi alloys". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI092.
Testo completoAbstract (sommario):
Les alliages Al-Cu-Li sont particulièrement attractifs pour les applications aéronautiques du fait de leur faible densité, haute limite d'élasticité et bonne ténacité. Ils reçoivent une attention particulièrement importante actuellement, depuis le développement de la troisième génération qui contient des concentrations relativement élevées pour le cuivre et relativement basses pour le Li. Ces nouveaux alliages sont caractérisés par une dureté élevée, une bonne résistance à la fatigue et une bonne stabilité thermique. La phase principale de durcissement est la phase T1 – Al2CuLi qui se présente sous la forme de plaquettes d'environ 1 nm d'épaisseur et 50 nm de diamètre, situées sur les plans {111} de la matrice avec une structure hexagonale. La germination efficace de cette phase durcissante entre en compétition avec d'autres précipités des sous-systèmes constituant ces alliages (comme Al-Cu et Al-Li), et nécessite des conditions particulières, en particulier la présence de dislocations (introduites par pré-déformation) et d'éléments d'alliage mineurs (Mg, Ag, Zn). Bien qu'il soit connu depuis longtemps que l'addition de ces éléments favorise la cinétique de précipitation dans ces alliages et le durcissement associé, leurs mécanismes d'action sont encore très mal compris.Dans ce contexte, l'objectif de la thèse est d'évaluer systématiquement l'effet des additions mineures de Mg, Ag et Zn sur la germination, la cinétique de précipitation et le durcissement correspondant. La caractérisation détaillée de la microstructure est utilisée pour comprendre les mécanismes de modification de la microstructure par les éléments mineurs. Les mesures de la diffusion des rayons X à petits angles et la DSC fournissent respectivement la cinétique de précipitation et la séquence de formation des phases. La microscopie électronique en transmission, utilisée en mode conventionnel, en résolution atomique et en mode de cartographie chimique met en évidence la structure et la distribution spatiale des phases. La dureté donne accès au durcissement. Des matériaux à gradient de concentration ont été élaborés et caractérisés pour évaluer l'effet de la concentration des alliages sur la précipitation et le durcissement.Les résultats mettent en évidence que le Mg est l'élément le plus efficace pour accélérer la cinétique de précipitation et de durcissement. L'addition d'Ag et de Zn augmente également la cinétique de précipitation mais dans une moindre mesure. L'addition de Mg change la séquence de précipitation tout au long de la séquence de vieillissement. La différence principale liée à la présence de Mg pour les premiers stades de traitement thermique est observée par rapport à la précipitation sur les dislocations. Dans les alliages qui contiennent du Mg, les dislocations sont décorées par des phases précurseur contenant de Cu et Mg. Par contre dans les alliages sans Mg celles-ci sont associés à des zones GP qui évoluent ensuite en précipités θ'. Cette différence est attribuée à la germination favorable de T1 sur les phases précurseur de Cu/Mg dans les alliages contenant du Mg, et par la saturation des sites de germination hétérogène par θ' dans les alliages sans Mg.L'augmentation de dureté associée à l'addition d'Ag et Zn est attribuée à une fraction volumique plus élevé de la phase T1. Ag est ségrège à l'interface entre T1 et la matrice et Zn est incorporé dans la structure de T1. Ces résultats suggèrent que les additions de Zn et Ag stimulent la formation de T1.L'influence de la concentration en éléments d'addition mineurs a été caractérisée par une approche résolue en temps et en espace, sur les matériaux contenant un gradient en composition. Cela révèle que l'effet de l'addition de Mg sur la précipitation se produit à une valeur seuil de ~0.1% en poids, suggérant que cela est la concentration nécessaire pour germer des phases précurseur sur les dislocations dans les premiers stades de la précipitationAl-Cu-Li alloys are very attractive for aerospace applications alloys due to their low density, high modulus and high strength. They are experiencing a strong interest since the so-called 3rd generation alloys, with relatively high Cu and low Li content, have been developed with high toughness, fatigue resistance and thermal stability. The main precipitating phase in these alloys is the T1-phase which precipitates on {111}Al-planes with a hexagonal structure. It is known that obtaining a fine dispersion of T1, and hence a high strength requires the presence of dislocations as nucleation sites. In addition, commercial Al-Cu-Li alloys contain several minor alloying elements such as Mg, Ag and Zn, which help reaching the desired properties. Although the effect of these minor additions on precipitation of T1 has been characterized, it has not been understood yet.In this context the aim of this thesis is to systematically investigate the effect of minor additions of Mg, Ag and Zn on precipitation nucleation, precipitation kinetics and related strengthening, and to use a detailed characterization of the microstructure to understand the mechanisms by which the modifications induced by these minor additions take place. In-situ Small-Angle X-ray Scattering and Differential Scanning Calorimetry provide the precipitation kinetics and sequence, respectively. Transmission Electron Microscopy, both in conventional mode, atomically-resolved and in chemical mapping mode, reveals the structure and distribution of phases. Hardness gives access to the strengthening. Compositionally gradient materials are fabricated and characterized to evaluate the effect of alloy composition on precipitation and strengthening.The results reveal that Mg is most effective in order to enhance precipitation kinetics and hardening. Additional Ag and Zn further enhance precipitation kinetics but to a lower extent. The addition of Mg changes the precipitation sequence at all times of ageing. The main differences in early aging conditions are observed with respect to precipitation on dislocations. In Mg-containing alloys, dislocations are decorated by Cu-Mg precursor phases, whereas dislocations in Mg-free alloys are mainly associated to GP-zones which evolve subsequently into θ'-phase. In fully precipitated conditions the microstructure of Mg-containing alloys is dominated by the T1 phase, whereas that of Mg-free alloys is dominated by the θ'-phase. This difference is attributed to the favourable nucleation of T1 on Mg-Cu precursor phases in the Mg-containing alloys, and to the consumption of T1-heterogeneous nucleation sites by the θ'-phase in the Mg-free alloys.The increase of hardness associated to the addition of Ag and Zn is associated to a higher volume fraction of the T1-phase. Ag was found to segregate at the T1/matrix interface and Zn was incorporated into the T1-phase, so that it is assumed that their additions stimulate the formation of T1.The influence of the concentration of the minor solute additions has been characterised by combined space and time-resolved experiments on compositionally gradient materials. It reveals that the effect of an Mg addition on precipitation occurs at a threshold level of ~0.1wt%, suggesting that this concentration is that necessary to form the precursor phase at the dislocations during early ageing
12
Medeiros, Rina Lourena da Silva. "Avalia??o das condi??es qu?mica e f?sica dos sedimentos do estu?rio Jundia?-Potengi". Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17612.
Testo completoAbstract (sommario):
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Previous issue date: 2009-02-27Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The aim of this study was to quantify the presence of major and minor elements in the sediments of the Jundia?-Potengi estuary, bordering the municipalities of Maca?ba, Natal and S?o Gon?alo do Amarante in the state of Rio Grande do Norte, Brazil, considering the evidence of anthropic activity along this estuary, resulting in pollution by treated and untreated wastewaters as well as those produced by industry and shrimp farming. The assessment of the environmental status of this estuary was based on physical-chemical parameters, such as granulometry, organic matter and the major (Al, Fe, Mn and P) and minor (Cd, Cr, Cu, Ni, Pb and Zn) elements found in sediment samples. Two collections were made at 12 georeferenced points along the channel of the estuary at different times. Granulometric analysis was carried out and the percentage of organic matter was determined. The sediments were microwave digested using acid digestion and quantitative analyses of the elements Al, Fe, Cd, Cr, Cu, Mn, Ni, P, Pb and Zn were performed by inductively coupled plasma optical emission spectrometry. Sediment analysis followed the methodology proposed by US EPA 3051A for total elements analysis. The small correlation between the organic matter and the elements studied here suggests that they are of geochemical rather than anthropic origin. The analytical results obtained from the bottom sediment samples in the study area show that the concentration of elements was below the reference values for standard shales (Turekian & Wedepohl, 1961) at the vast majority of points analyzed, ruling out a possible contamination by metals
Este trabalho teve como objetivo avaliar, por meio da quantifica??o, a presen?a dos elementos maiores e menores nos sedimentos do Estu?rio Jundia?-Potengi localizado as margens dos munic?pios de Maca?ba, Natal e S?o Gon?alo do Amarante no Estado do Rio Grande do Norte, considerando as evid?ncias de atividades antr?picas ao longo deste estu?rio, no qual se destacam a polui??o por efluentes dom?sticos, tratados e sem tratamento, efluentes industriais e de carciniculturas. A avalia??o do estado ambiental desse estu?rio foi feito atrav?s da determina??o dos par?metros f?sicoqu?micos, como granulometria, mat?ria org?nica e elementos maiores, Al, Fe, Mn e P, e elementos menores, Cd, Cr, Cu, Ni, Pb e Zn em amostras de sedimento deste estu?rio. As coletas foram feitas em 12 pontos, georefer?nciados, na calha, ao longo desse estu?rio, e em duas coletas com per?odos distintos. Foram feitas as determina??es das porcentagens de mat?ria org?nica e a an?lise granulom?trica. A digest?o dos sedimentos foi feita com um aparelho de microondas por digest?o ?cida e as an?lises quantitativas dos elementos Al, Fe, Cd, Cr, Cu, Mn, Ni, P, Pb e Zn por espectrometria de emiss?o ?tica com plasma acoplado indutivamente Para a an?lise dos sedimentos tomou-se como refer?ncia a metodologia proposta pela US EPA 3051A para a an?lise dos elementos. A pequena correla??o da mat?ria org?nica com os elementos estudados neste trabalho sugere que estes n?o sejam de origem antr?pica e sim de suporte geoqu?mico. Os resultados anal?ticos apresentados pelas amostras de sedimentos de fundo para a ?rea estudada mostraram que a concentra??o dos elementos ficou abaixo dos valores de refer?ncia do folhelho padr?o de Turekian & Wedepohl (1961) na grande maioria dos pontos analisados, descaracterizando uma poss?vel contamina??o por metais
13
LEITE, TACITO DANTAS FROTA. "DETERMINATION OF MAJOR, MINOR AND TRACE ELEMENTS IN ROCK SAMPLES BY LA-ICPMS AFTER TARGET PREPARATION BY FUSION WITH LITHIUM BORATES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8759@1.
Testo completoAbstract (sommario):
PETRÓLEO BRASILEIRO S. A.A determinação de elementos traços em amostras de rocha por espectrometria de massas, combinada com ablação a laser (LA-ICPMS), tem se tornado uma importante ferramenta nas investigações em petrogênese, metalogênese e na prospecção de minérios. Apesar do surgimento de uma nova geração de lasers com menor duração de pulso (fs) e comprimento de onda (<266 nm), a calibração é ainda um ponto crítico, pois em geral, não há padrões disponíveis com matriz semelhante. Uma das interferências não espectrais mais relevantes em LA-ICPMS é o fracionamento químico, o qual acarreta diferenças entre as composições do alvo (padrão ou amostra) e da massa ablacionada, comprometendo a exatidão e a repetitividade dos resultados. Quando a análise integral é o objetivo principal, o assemelhamento de matriz pode ser alcançado por simples fusão das amostras e padrões em misturas de meta e tetraboratos, de modo similar ao que é feito, rotineiramente, na análise por fluorescência de raios-X (XRFA). Este trabalho relata metodologia para a determinação de elementos traços em amostras de basaltos, provenientes de sítios de exploração de petróleo. Os experimentos foram realizados com um sistema de ablação a laser CETAC LSX-100 em combinação com um espectrômetro ELAN 5000 ICPMS. Uma mistura de argônio-nitrogênio (2 % N2, 98 % Ar) foi utilizada como gás carreador, com o intuito de aumentar a massa ablacionada, e consequentemente, melhorar as intensidades de sinal e reduzir os limites de detecção. Conectou-se uma câmara ciclônica antes da tocha do ICP, com o objetivo de uniformizar o tamanho das partículas de aerossol, e deste modo, melhorar a repetitividade da medição e a robustez do plasma. A título de comparação, análises também foram feitas sem o emprego desta câmara. Padrões de calibração foram preparados a partir de dois materiais de referência certificados, o basalto NIST SRM 688 e a obsidiana NIST SRM 278. Os padrões de rochas pulverizadas foram misturados e homogeneizados com fundente de borato de lítio (CLAISSE, puro, 75 % Li2B4O7, 25 % LiBO2) nas proporções mássicas de rocha: fundente de 1:5, 1:11, 1:23, 1:47, respectivamente, obtendose, deste modo, cada padrão em quatro diferentes concentrações. O padrão interno escolhido foi o In, tendo sido este adicionado antes da fusão, resultando em alvos com a concentração de 100 mg kg(-1) neste elemento. Obtiveram-se os brancos, de modo similar, usando o fundente borato de lítio. A validação metodológica foi feita empregando-se o basalto (GSJ, JB-2) e o granito (NIMG, SARM-1), tendo sido a partir destes, preparados vidros com a proporção mássica (amostra: fundente) de 1:5 e contendo o padrão interno. Todas as fusões foram feitas em um forno de fusão automático (CLAISSE Fluxy). Análises por ICPMS e ICP OES foram feitas após dissolução de fragmentos dos alvos em HNO3, para verificação de possíveis perdas de elementos voláteis. Quarenta elementos foram determinados, a maioria das curvas de calibração apresentou coeficiente de determinação (R2) maiores que 0,995. Limites de detecção variaram de 0,013 mg kg(-1) para Tb, até 0,6 mg kg(-1) para Zn. Estes valores foram melhorados para vários elementos pelo uso da câmara ciclônica (V, Zn, Rb, Y, Nb, Ba, Ce, Sm, Tb, Dy, Ho, Tm). Nas análises do basalto (GSJ, JB-2) e do granito (NIMG, SARM-1), a exatidão foi melhor do que 5 % para V, Sr, Y, Ba, Ce, Nd, Yb e Lu; entre 5-10 % para: Sc, Zn, Rb, Tm, e de 10-20 % para: Co, Zr, La e Tb. A repetitividade foi melhor do que 5% para V, Rb, Sr, La, Nd, Ta; entre 5-10 % para: Sc, Co, Zn, Sr, Y, Zr, Ba, Tb, Yb; e de 10-20 % para: Ce, Tm, Lu e Hf. Foi utilizado ainda o método semiquantitativo TotalQuant II o qual, dentro da incerteza esperada para este tipo de calibração (cerca de 10 % a 20 %), forneceu resultados concordantes com calibração externa quantitat
Determination of trace elements in rock samples by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) has become an important tool for investigations in petrogenesis, metallogenesis and ore prospecting. However, despite the availability of new generation lasers with shorter pulse duration (fs) and wave length (<266 nm), calibration remains still a critical issue when matrixmatched standards are not available. One of the most serious non- spectral interference in LA-ICPMS is chemical fractionation, which causes compositions of standard and sample and their respective ablated masses to be different, thus compromising accuracy and precision of the results. When bulk analysis is the main objective, matrix matching can be achieved by the simple fusion of samples and standards with meta/tetraborates fluxes, similar to what is routinely used in XRFA. This work reports on our experience with this procedure in the analysis of basaltic rocks, aiming at the trace element characterization of host rocks from oil exploration sites in Brazil. The experiments were performed with a CETAC LSX- 100 laser ablation system (Nd:YAG, 266 nm, operated in the Q-switched and scanning mode) coupled to an ELAN 5000 ICPMS. An argon- nitrogen mixture (2 % N2, 98 % Ar) was used as carrier gas to enhance the mass of material ablated, thus increasing signal intensities and reducing detection limits. A cyclonic spray chamber was arranged just before the ICP-torch as a tentative to uniform aerosol particle size for improving measurement repeatability and robustness of the plasma. For comparison, the system was also operated without a spray chamber. Calibration samples were prepared from two standard reference materials: NIST SRM 688 basalt and NIST SRM 278 obsidian. The powdered rock standards were mixed and homogenized with a lithium borate flux (CLAISSE, pure, 75 % Li2B4O7, 25 % LiBO2) using rock-to-flux mass ratios of 1:5, 1:11, 1:23 and 1:47, respectively, thus obtaining each standard in four different analyte concentrations. Indium was used as an internal standard (IS) and was added before fusion to achieve targets with IS concentration of 100 mg kg(-1). Blanks from the lithium borate flux were produced in a similar way. Method validation was performed with GSJ basalt JB-2 and NIMG granite SARM-1, prepared at a constant sampleto- flux mass ratio of 1L:5 and containing also the IS. All fusions were performed in an automated furnace (CLAISSE Fluxy). Solution nebulization ICP-MS/OES after dissolution of smaller target pieces in HNO3 was used to assess for volatilization losses. Forty elements were determined and good linearity of the calibration curves was obtained and for most of them the correlation coefficient (R2) was higher than 0.995. Detection limits ranged from 0.013 mg kg(-1) for Tb to 0.6 mg kg(-1) for Zn, and improved for several elements by using a cyclonic spray chamber (e.g. V, Zn, Rb, Y, Nb, Ba, Ce, Sm, Tb, Dy, Ho, Tm). In the analysis of GSJ basalt JB-2 and NIMG granite SARM-1, accuracy was better than 5 % for: V, Sr, Y, Ba, Ce, Nd, Yb, and Lu; between 5-10 % for: Sc, Zn, Rb, Tm, and 10-20 % for: Co, Zr, La and Tb. Repeatability was better than 5 % for: V, Rb, Sr, La, Nd, Ta, between 5-10% for: Sc, Co, Zn, Y, Zr, Ba, Tb, Yb, and 10-20 % for: Ce, Tm, Lu and Hf. Additionally, the semiquantitative TotalQuant II calibration was applied, which gave, within the expected uncertainty for this calibration method (10 % to 20 %), concordant results when compared to the quantitative external calibration procedure. Preliminary results on the application of these methods for the determination of trace elements in basaltic host rocks from oil exploration sites will be shown.
14
JUNIOR, RAINERIO ESCALFONI. "DETERMINATION OF MINOR AND TRACE ELEMENTS IN ROCK SAMPLES BY LA-ICPMS: PROGRESS IN THE UTILIZATION OF BORATE GLASSES AS TARGETS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15411@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA presente dissertação é uma continuação de pesquisas desenvolvidas por Leite (2006) visando à análise multielementar de rochas (basaltos, obsidianas e folhelhos) por espectrometria de massa com plasma indutivamente acoplado (ICPMS), em combinação com ablação a laser (LA) e utilizando-se vidro borato como alvo de análise. Como no trabalho anterior, os experimentos foram realizados com um sistema LSX-100 (CETAC) acoplado ao espectrômetro Elan 6000 ICPMS (PerkinElmer-Sciex). Como gases carreadores na câmara de ablação foram testados gases puros (Ar, He) e misturas (Ar-He, Ar-N2). Também foram avaliados parâmetros operacionais do laser, tais como: energia de saída, focalização, velocidade de varredura e freqüência de disparo. As novas condições analíticas foram testadas com os padrões preparados por Leite (2006), calculandose os limites de detecção, a exatidão e precisão. Os limites de detecção para 40 elementos (Na, Al, Si, P, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Rb, Sr, Y, Zr, Nb, Sb, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, Th, U) ficaram compreendidos entre 0,004 mg kg-1 (Tb) e 850 mg kg-1 (Si). Exatidões foram estimadas a partir de análises de materiais de referência certificados (USGS BIR-1, BHVO-2, SCo-1), obtendo-se erros < 10% para Sc, V, Co, Ni, Zn, Rb, Y, Ba, La, Pr, Nd, Tb, Lu e Th e entre 10-20% Na, Al, Si, P, K, Ca, Mn, Fe, Ga, Sr, Y, Zr, Nb, Ce, Sm, Eu, Gd, Dy, Er, Yb, Lu, Hf e U. Precisões, calculadas a partir dos desvios-padrão residuais das curvas de calibração, ficaram em média em 6%, sendo de no máximo 10% para 30 elementos (Na, Al, Si, P, Ca, Sc, V, Cr, Mn, Fe, Co, Zn, Ga, Sr, Y, Zr, Sb, La, Ce, Pr, Eu, Gd, Tb, Dy, Er, Tm, Yb, Lu, Hf e Ta). Foram preparados novos padrões de calibração a partir de dois materiais de referência certificados, o basalto USGS BCR-2 e o folhelho USGS SGR-1. Os novos padrões foram validados utilizando os padrões preparados por Leite (2006) e através de análises independentes. Os coeficientes de determinação (R2) para 24 elementos (Na, Mg, Al, K, Sc, V, Cr, Mn, Fe, Co, Ga, Rb, Sr, Y, Nb, Ce, Nd, Eu, Ho, Yb, Lu, Ta, Pb, U) foram maiores que 0,98 e para os outros 16 elementos, no mínimo, maiores que 0,95 (Si, P, Ca, Zn, Zr, Ba, La, Pr, Sm, Gd, Tb, Dy, Er, Tm, Hf, Th). As metodologias foram utilizadas na caracterização multielementar de amostras de folhelhos, de grande interesse geológico na área de petróleo, e os resultados preliminares são apresentados e discutidos.
The present master dissertation is a continuation of a research study developed by Leite (2006) aiming at the multielemental analysis of rock samples (basalts, obsidians and shale) by inductively coupled plasma mass spectrometry (ICPMS), in combination with laser ablation (LA) and using borate glass as analytical targets. As in the former work, the experiments were performed with a LSX-100 (CETAC) system coupled to an Elan 6000 ICPMS (PerkinElmer-Sciex). Pure gases (Ar, He) and mixtures (Ar-He, Ar-N2) were tested as carrier gas for transporting the aerosol from the ablation cell to the plasma. Different operational parameters of the laser, such as energy, focus, scanning speed and laser frequency were also studied. The new and optimized analytical conditions were tested with the calibration standards prepared by Leite (2006), and limits of detection (LOD), accuracies and precisions (RSD) were estimated. For 40 elements (Na, Al, Si, P, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Rb, Sr, Y, Zr, Nb, Sb, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, Th, U), the LODs were in the range of 0,004 mg kg-1 (Tb) and 850 mg kg-1 (Si). Accuracies, estimated from the analysis of certified reference materials (USGS BIR-1, BHVO-2, SCo-1), were better 10% for Sc, V, Co, Ni, Zn, Rb, Y, Ba, La, Pr, Nd, Tb, Lu, and Th, and between 10 to 20% for Na, Al, Si, P, K, Ca, Mn, Fe, Ga, Sr, Y, Zr, Nb, Ce, Sm, Eu, Gd, Dy, Er, Yb, Lu, Hf, and U. Analytical precisions, calculated from the residual standard deviations of calibration curves were typically 6%, and at most 10% for 30 elements (Na, Al, Si, P, Ca, Sc, V, Cr, Mn, Fe, Co, Zn, Ga, Sr, Y, Zr, Sb, La, Ce, Pr, Eu, Gd, Tb, Dy, Er, Tm, Yb, Lu, Hf, Ta). New targets were prepared from two certified reference materials: (USGS BCR-2 (basalt) and USGS SGR-1 (shale). These new calibration standards were validated against those prepared by Leite (2006) and also by an independent technique. Coefficients of determination (R2) for 24 elements (Na, Mg, Al, K, Sc, V, Cr, Mn, Fe, Co, Ga, Rb, Sr, Y, Nb, Ce, Nd, Eu, Ho, Yb, Lu, Ta, Pb, U) were better than 0.98, and for further 16 elements better than 0.95 (Si, P, Ca, Zn, Zr, Ba, La, Pr, Sm, Gd, Tb, Dy, Er, Tm, Hf, Th). The method was then used for the multielement characterization of marine shale samples, which are of great geological interest in petroleum research, and preliminary results are presented and discussed.
15
Johnston, Murray. "Thermodynamics of selenium and tellurium in molten metallurgical slags and alloys". University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0064.
Testo completoAbstract (sommario):
There are a number of impurity elements present in sulphide ores that can have a deleterious effect on the properties of the final copper metal product. In this thesis, an equilibrium distribution technique was used to determine the thermodynamic behaviour of selenium and tellurium in molten slags used in copper production. Calcium ferrite based slags and copper or silver alloy were equilibrated in magnesia crucibles at temperatures of 1200 to 1400 °C and oxygen partial pressures of 10-11 to 10-0.68 atm. Under conditions typical of those employed during copper converting, the minor elements were found to enter the slag as negatively charged species. The partitioning of selenium and tellurium to the slag was greatest at high temperature, low oxygen partial pressure and at highest concentration of basic oxide (CaO or BaO). The experimentally derived data were combined with published information to calculate the selenide and telluride capacities of the slag, and also to generate fundamental thermodynamic activity data for selenium and tellurium in the slag phase. It was found that the activity coefficients of selenium and tellurium were independent of their concentration in the slag over the range studied, but were strongly dependent on the temperature, slag chemistry and oxidation state of the slag. Experiments were also designed and carried out to determine what effect the presence of iron oxide and its oxidation state has on the behaviour of selenium in the slag. A series of experiments involving iron oxide additions to a calcium aluminate slag was conducted under increasingly oxidising conditions to assess the effect of total iron on the selenide capacity as the dominant oxidation state of iron in the slag changed. It was shown that at a constant ratio of CaO:Al2O3, the selenide capacity increased with total iron in the slag. However, the effect on the selenide capacity did not appear any more significant as the Fe3+:Fe2+ ratio changed in a particular direction. 4 Another series of experiments was carried out with iron calcium silicate slags to determine the stability of phases within the slag, and how this affected the equilibrium distribution and activity coefficient of selenium in the slag. A number of solid phases were identified and their composition determined by scanning electron microscopy, energy dispersive spectroscopy and electron microprobe analysis. The composition and minor element content of the remaining liquid was calculated using a thermodynamic model. From this it was found that the capacity of the liquid slag has a region of independence against slag chemistry, before increasing strongly with increasing lime content to the calcium ferrite composition. Some of the implications of this work are discussed with reference to the practicality of adjusting the process variables in a large-scale industrial process for the purpose of managing minor element content of the molten phases. Considerations include the effect on copper recovery and rate of wear of furnace refractory materials.
16
Choi, Yun Jung. "The use of the Polish folk music elements and the fantasy elements in the Polish fantasy on original themes in G-sharp minor for piano and orchestra, opus 19 by Ignacy Jan Paderewski". Thesis, Lecture recital, recorded Mar. 6, 2006, in digital collections. Access restricted to the University of North Texas campus connect to online resource, 2007. http://digital.library.unt.edu/permalink/meta-dc-3690.
Testo completo
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Eastell, Julie. "A low dilution fusion technique for the determination of major, minor and trace elements in Lamproite and Kimberlite samples by X-ray fluorescence spectrometry". Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/21888.
Testo completoAbstract (sommario):
Bibliography: pages 200-204.A low dilution fusion technique using a 2:1 flux:sample ratio has been developed for the accurate determination of major, minor and trace elements by x-ray fluorescence spectrometry (XRFS). This method has been used to analyze geological samples of widely varying and unusual composition such as lamproites and kimberlites. The results are shown to be of comparable if not better accuracy than other methods of sample preparation for XRFS. Analytical conditions, including corrections for spectral line interferences are reported for all the elements determined. For major element analysis three methods of calculating appropriate alpha coefficients were investigated, namely (1) multiple regression analysis, (2) Norrish and Hutton method and (3) a computer program, NBSGSC, involving fundamental parameters and the COLA equation. Methods (1) and (2) gave poor results for rock types of widely varying composition. The third method requires that the variation of alpha coefficients with varying weight fraction of the analyte element be taken into account when calculating alpha coefficients if accurate values for major and minor elements are to be obtained on low dilution fusion discs. For trace element analysis the average relative error was less than 5% and there was a decrease in sensitivity by about a factor of 2 compared with XRFS determinations on powder pellets. The elimination of particle size effects in the homogeneous glass fusion discs is a major advantage over the use of powder pellets, especially for the determination of elements such as Ba, Cr and the REEs. A loss on fusion technique has been employed to ensure complete loss of volatiles from the rock samples. Data presented highlight the problems encountered in the determination of the volatile content in geological samples. The oxidation and retention of sulphur in the discs was also investigated.
18
Al-Ebraheem, Alia. "Measurement of Levels and Distribution of Important Trace and Minor Elements and the Investigation of their Role in Cancer using X-ray fluorescence and X-ray Absorption Techniques". Thesis, City University London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521080.
Testo completo
19
da, Silva Ashley. "Investigation of Cretaceous Molluscan Shell Material for Isotopic Integrity: Examples and Implications from the Baculites compressus/cuneatus Biozones (Campanian) of the Western Interior Seaway". Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3921.
Testo completoAbstract (sommario):
Whether a global greenhouse interval is a distinct or distant future, it is important
to understand the dynamics of a greenhouse system. During such intervals the oceans, in
the absence of sizeable polar ice caps, flood the continental shelf. The stratification and
circulation of these epicontinental seas are open to debate, because there are no Recent
analogs. The carbon and oxygen stable isotope record of fossil molluscan shell from
epicontinental seas has the potential to reveal their stratification and seasonal cycles.
Whether a global greenhouse interval is a distinct or distant future, it is important
to understand the dynamics of a greenhouse system. During such intervals the oceans, in
the absence of sizeable polar ice caps, flood the continental shelf. The stratification and
circulation of these epicontinental seas are open to debate, because there are no Recent
analogs. The carbon and oxygen stable isotope record of fossil molluscan shell from
epicontinental seas has the potential to reveal their stratification and seasonal cycles.
As a study sample, mollusks from the
Baculites compressus and Baculites
cuneatus
biozones of the Western Interior Seaway of North America were collected from
three locations: Kremmling, Colorado; Trask Ranch, South Dakota; Game Ranch, South
Dakota. These fossils date to the Campanian (Late Cretaceous). Taxa include
ammonites, bivalves, gastropods, and nautiloids.
The first part of this investigation, described in Chapter 2, investigates the degree
of alteration in these specimens. Elevated concentrations of minor elements such as
magnesium and strontium reveal alteration from the original aragonite and/or calcite
skeletons. Concentrations of these elements obtained by ICP-OES analysis are compared
within several suites of specimens: mode of preservation, shell testing location, shell
color, cementation, appearance under light microscope, and appearance under scanning
electron microscope. Each of these suites tests a hypothesis about optimal shell
preservation. Shell was found to be preserved best in shale rather than concretions,
ammonite phragmacone rather than septa, opalescent specimens rather that nonopalescent
ones, and uncemented shells rather than cemented shells, especially those with
second-order versus first-order cement. Salinity and temperature values were derived for
the organisms in the Western Interior Seaway: while bivalves produced unusually low
temperatures, the others were reasonable for an inland sea.
The second part of this study, described in Chapter 3, examines the isotopic
record within exemplary mollusk shells, taken perpendicular to growth lines. The data
for this investigation in sclerochronology documents the dominant isotopically enigmatic
bottom-water habitat of the
Inoceramus, the geochemical signature of the overlying water
mass inhabited by
Baculites, and short-term migrations between the two water masses in
the nautiloid
Eutrephoceras.
20
Mazaltarim, Daniel. "Geochimie des cuirasses ferrugineuses et bauxitiques de l'afrique occidentale et centrale". Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13090.
Testo completoAbstract (sommario):
Dans les pays tropicaux d'afrique ou regnent des climats chauds et humides, le substratum rocheux est separe de la surface par une epaisse couverture lateritique, parfois coiffee d'un niveau tres riche en fer et indure appele cuirasse. Le but de ce travail est, sur la base d'un modele d'enfoncement vertical des paysages lateritiques, de comprendre par quels mecanismes les caracteres chimiques, mineralogiques ou texturaux des materiaux parentaux peuvent se perpetuer ou disparaitre au cours de l'alteration. La prospection geochimique des ressources minerales du substratum rocheux des pays d'afrique occidentale et centrale, est tributaire de ces enseignements. On montre ainsi que l'augmentation des teneurs en fer dans les cuirasses, ou en alumine dans les bauxites, s'accompagne d'une homogeneisation des compositions chimiques
21
Pei, Yushu. "An Analysis of the Attempted Amalgamation of Western and Chinese Musical Elements in Huang Anlun's Piano Concerto in G Minor, Opus 25b, a Lecture Recital, Together with Three Recitals of Selected Works by Bach, Beethoven, Chopin, Liszt, Mozart, Schubert, and Schumann". Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc935793/.
Testo completoAbstract (sommario):
While China possesses one of the world's richest musical heritages, it remained unaffected by Western music until early in this century. Subsequently, there was a movement of nationalism in music approximately three decades after the introduction of Western music. This movement, aimed at utilizing Western compositional techniques to create musical works that still would be uniquely Chinese, continues even today. Huang's piano concerto was written in 1982, just a few years after the Cultural Revolution. At the time, most Chinese composers were "handicapped" by their lack of knowledge of Western contemporary music and by their limited study of both Western and Chinese traditional forms. Huang Anlun, a composer-in-residence at the Central Opera House in Beijing, traveled to North America to study at the University of Toronto and Yale University. Subsequently his music is widely performed and well received around the world. After presenting background information on Western music in China and an introduction to basic Chinese music theory, this study has analyzed Huang's piano concerto, with a particular focus on identifying, comparing, and analyzing elements of Western and Chinese music. After a survey of the formal structure of the concerto, this study has discussed Chinese modality and Western harmony--the two most important factors in the conception of Huang's concerto. A comparative study between Chinese folk songs and the thematic materials in Huang's concerto is followed by a discussion on "imitations" of Chinese instruments. The study has also examined Western compositional techniques incorporated into this concerto, such as thematic transformation, contrapuntal writing, cyclic procedure, as well as atonal and serial techniques. Through a detailed analysis, this study attempts to demonstrate how Huang has blended Western and Chinese musical syntaxes to create an artistic work that is also uniquely Chinese.
22
Gordon, Christopher Paul. "Major, minor and trace element geochemistry of Taiwan bedrock /". Connect to resource, 2006. http://hdl.handle.net/1811/21998.
Testo completo
23
KATTAN-ZUHAIR. "Geochimie et hydrologie des eaux fluviales des bassins de la moselle et de la mossig : transports dissous et particulaire, cycles biogeochimiques des elements". Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13050.
Testo completoAbstract (sommario):
Une importance particuliere a ete apportee a la combinaison entre les informations hydrologiques et chimiques. En effet, le controle de la dynamique actuelle de transferts des elements vers les fleuves est fonction de variations hydroclimatiques qui reglent le cycle de l'eau. Rappelons les principaux resultats acquis. La particularite des bassins de la moselle et de la mossig vient de leur position geographique appartenant a la region dite temperee industrielle. L'etude des facteurs hydrologiques d'un bassin versant necessite une bonne connaissance de divers elements controlant le cycle de l'eau. L'etude de la composition chimique des eaux de surface a permis de deceler l'influence des rejets de pollution des soudieres. Ces pollutions deteriorent completement le signal chimique naturel porte par les eaux. La nature mineralogique des matieres en suspension est caracterisee par une forte contribution des mineraux argileux interstratifies de types 14v-14m, 14c-14m et 14c-14v (40 %) et d'illite (30 %). Le mecacnisme qui regle le piegeage geochimique du phosphore dans les eaux fluviales est l'adsoprtion sur les mineraux argileux. Bien que la sursaturation des eaux vis-a-vis de l'hydroxyapatite est tres elevee, la presence de ce mineral n'a pu etre decelee dans les sediments de la moselle et de la mossig. L'etude des relations debit-concentration a permis de caracteriser l'origine des elements, de calculer les flux de matieres exportees a l'echelle des crues comme a l'echelle d'un cycle hydrologique. Le transport en solution par la moselle et la mossig domine fortement l'exportation solide. Les cycles biogeochimiques des elements majeurs sur le bassin de la moselle sont en grande partie controlee par les pollutions de toutes sortes. La moselle, comme toutes les rivieres des regions soumises a de fortes pollutions, confirme l'action de l'homme comme pertubateur des phenomenes naturels
24
Witherow, Rebecca A. "Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-Basin Lakes". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250628213.
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Bouabsa, Lakhdar. "Intrusions granitiques à albite et topaze : Minéralisations stanno-wolframifères et altérations hydrothermales associées, l'exemple du hoggar central, Algérie". Nancy 1, 1987. http://www.theses.fr/1987NAN10329.
Testo completoAbstract (sommario):
Le présent travail met l'accent sur la dualité du magmatisme de cette région du Hoggar Central. Outre un granite banal à biotite (parfois amphibole) constituant l'ossature principale des granites post orogéniques (Taourirts), il est mis en évidence un type particulier de granite spécialisé à albite, topaze et protolithionite comme paragénèse I. Ce magmatisme évolué est sans liaison génétique avec le précèdent comme le soulignent les contacts intrusifs marqués par des stockscheiders et les discontinuités géochimiques au niveau des éléments majeurs et tracés. La liaison spatiale et génétique des altérations hydrothermales avec ce magmatisme spécialisé apparait évidente. Ces altérations affectent les différents termes magmatiques de la région ; Elles sont essentiellement lithinifères, fluorées (protolithionite, muscovité lithinifère, topaze et fluorine) et peuvent conduire à des phénomènes de convergence à partir des granites banaux à biotite. Les minéralisations SN-W, déjo exprimées de façon primaire dans les granites à albite - topaze, sont liées au développement de ces altérations greisénisantes fissurales
26
Santos, Duilio Ferreira. "Elementos da teoria algébrica das formas quadráticas e de seus anéis graduados". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/45/45131/tde-22062016-104927/.
Testo completoAbstract (sommario):
Neste trabalho procuramos realizar uma apresentação autocontida sobre os conceitos da teoria algébrica de formas quadráticas e sobre os anéis graduados que surgiram no desenvolvimento desta teoria. Iniciamos procurando esclarecer o sentido da equivalência entre as várias acepções do conceito de forma quadrática. Após a apresentação de ingredientes e resultados geométricos, fazemos um extrato da teoria dos anéis de Witt, conceito que originou a moderna teoria algébrica de formas quadráticas. Disponibilizamos os elementos fundamentais para a formulação das teorias de cohomologia, nos concentrado no desenvolvimento da teoria de cohomologia profinita e, sobretudo, galoisiana. Descrevemos os funtores K0, K1 e K2 da K-teoria clássica e também a K-teoria de Milnor, que é mais adequada para formular questões sobre formas quadráticas. Finalizamos o trabalho com a apresentação de alguns conceitos da Teoria dos Grupos Especiais, uma codificação em primeira-ordem da teoria algébrica das formas quadráticas e exemplificamos sua importância, fornecendo um extrato da prova realizada por Dickmann-Miraglia da conjectura de Marshall sobre assinaturas, que se baseia fortemente nesta teoria.In this work I try to provide a self-contained presentation on the concepts of algebraic theory of quadratic forms and on the graded rings that have emerged in the development of this theory. I started trying to clarify the meaning of \"equivalence\"between the various meanings of the concept of quadratic form. After the presentation of geometrical ingredients and results, we make an extract of the theory of Witt rings, a concept that originated the modern algebraic theory of quadratic forms. It is provided the key elements for the formulation of cohomology theories, focusing on the development of profinite cohomology theory and, especially, on galoisian cohomology. Are described the functors K0, K1 and K2 of classical K-theory and also the Milnor K-theory, which is more appropriate to formulate questions about quadratic forms. The dissertation is finished with the presentation of some concepts of the Theory of Special Groups, a first-order encoding of algebraic theory of quadratic forms, and with an example its importance by providing an extract of proof by Dickmann-Miraglia of the Marshalls conjecture on signatures, which relies heavily on this theory.
27
YAMAMOTO, Koshi, Kango NAKAMARU e Mamoru ADACHI. "Depositional environments of "accreted bedded cherts" in the Shimanto terrane, Southwest Japan, on the basis of major and minor element compositions". Dept. of Earth and Planetary Sciences, Nagoya University, 1997. http://hdl.handle.net/2237/2832.
Testo completo
28
Balmelle, Laurent. "Etude de la série volcano-sédimentaire de La Chapelle-sous-Dun (Massif du Charollais, Nord-Est du Massif Central français)". Paris 6, 1986. http://www.theses.fr/1986PA066494.
Testo completoAbstract (sommario):
L'etude des formations volcaniques associees au bassin stephanien de la chapelle-sous-dun (charollais) permet de preciser les relations entre phenomenes magmatiques et post-magmatiques d'une part, et les indices ou anomalies geochimiques (u. F. ) d'autre part. Les formations volcaniques font partie d'un ensemble plutono-volcanique complexe. La localisation de ces phenomenes est guidee par le contexte structural et, en particulier, l'existence de zones de type pull-apart dans un contexte compressif generalise. Les phenomenes post-magmatiques, en particulier la devitrification des roches volcaniques, sont fonction des natures lithologiques initiales. Les phenomenes d'evolution post-magmatique de la pile volcanique ont amene une liberation de l'u et son piegeage dans les biotites chloritisees, elles aussi associees aux processus secondaires. Toutefois, le mecanisme du piegeage de l'u n'a pu etre precise. Des phenomenes limites de remobilisations hydrothermales ou supergenes peuvent etre a l'origine des indices reconnus dans le stephanien
29
Galdino, Luciano. "CALFRAC: Programa que quantifica o processo de cristalização fracionada e sua aplicação ao estudo de soleiras da Bacia do Paraná (Estado do Paraná)". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-03012011-135433/.
Testo completoAbstract (sommario):
Foi desenvolvido um programa computacional escrito na linguagem de programação C++ denominado CALFRAC para quantificar o processo de cristalização fracionada em sistemas ígneos, utilizando para isso as concentrações dos elementos maiores, menores e traços. O algoritmo moderniza, torna mais eficiente e aprimora os programas publicados na literatura e possui a grande vantagem de poder calcular, automaticamente, todas as possíveis combinações de evolução das amostras envolvidas na diferenciação, além de associar aos cálculos os elementos-traço, os quais servem para confirmar os resultados sugeridos pelos ajustes dos elementos maiores e menores. O CALFRAC calcula a fração total subtraída do magma inicial e as frações referentes a cada mineral fracionado através do cálculo do balanço de massa, utilizando as concentrações de elementos maiores e menores, empregando os métodos de estimativa de máxima verossimilhança e dos multiplicadores de Lagrange para a resolução por mínimos quadrados, enquanto para os elementos-traço o programa utiliza a Equação de Rayleigh. Em ambos os casos a média dos erros percentuais relativos é usada como indicação das melhores evoluções. O programa CALFRAC foi aplicado na investigação da possibilidade de diferenciação por cristalização fracionada em amostras de soleiras de diabásio da Bacia do Paraná, que ocorrem nos municípios de Salto do Itararé, Ponta Grossa, Prudentópolis, Rebouças, Irati, Reserva e Jaguariaíva (PR), as quais foram coletadas para essa finalidade. Nas 33 amostras coletadas foram realizadas determinações de elementos maiores, menores e traços, incluindo terras raras, empregando-se os métodos de Fluorescência de Raios X e Ativação Neutrônica. Os resultados fornecidos pelo programa foram insatisfatórios, não sendo possível estabelecer um percurso de diferenciação das rochas mais primitivas para as mais diferenciadas das intrusões, devido ao fato de que provavelmente muitas das amostras analisadas representam a mistura de magmas com porções contendo acumulação de fases minerais causada pelo próprio processo de cristalização fracionada in situ.CALFRAC is a computer program written in C++ programming language developed to quantify fractional crystallization processes in igneous systems. Major, minor and trace element concentrations are used as input for calculations. The new algorithm enhances and makes the program more efficient than those published in the literature. Besides it is capable to automatically calculating all possible rock sample combinations involving differentiation by fractional crystallization process, using in addition trace element concentrations to corroborate the results obtained by the fitting of major and minor element abundances. CALFRAC calculates the total fraction subtracted from the original magma and the percentage of each fractionated mineral by solving least-squares mass balance equations based on major and minor element concentrations. The methods of maximum likelihood estimate and Lagrange multipliers are used to solve the equations, whereas for the quantification of trace elements the program uses the Rayleigh Equation. In both cases the mean relative percentage errors is used as an indication of the best results. The program CALFRAC was applied to investigate the possibility of differentiation by fractional crystallization of diabase samples from Paraná Basin sills, which outcrop nearby Salto do Itararé, Ponta Grossa, Prudentópolis, Rebouças, Irati, Reserva and Jaguariaíva towns (PR). The 33 collected samples were analyzed for major, minor and trace elements, including rare earths, employing X-Ray Fluorescence and Neutron Activation methods. The program output was not satisfactory, since it was not possible to establish a differentiation sequence from the more primitive to the more differentiated rocks of the intrusions. This is probably due to the fact that many rock samples are the result of mixing of magmatic melts with mineral accumulation zones, which were formed by the in situ fractional crystallization process.
30
Dekeyzer, Stefanie [Verfasser], Karin [Akademischer Betreuer] Zonneveld e Simone [Akademischer Betreuer] Kasemann. "Minor element composition and stable oxygen isotopes of calcareous shells of the dinoflagellate Thoracosphaera heimii / Stefanie Dekeyzer. Gutachter: Karin Zonneveld ; Simone Kasemann. Betreuer: Karin Zonneveld". Bremen : Staats- und Universitätsbibliothek Bremen, 2012. http://d-nb.info/1071992988/34.
Testo completo
31
Schmitt, Jean-Michel. "Albitisation triasique, hydrothermalisme jurassique et alteration supergene recente. Metallogenie des gisements uraniferes du rouergue". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13173.
Testo completoAbstract (sommario):
Les concentrations uraniferes qui font l'objet de ce travail sont des gites multifissures, de paragenese simple, quasi monometallique, ou l'uranium s'exprime sous forme d'oxydes. Elles se localisent aussi bien dans le socle que dans les sediments permo-carboniferes et recoupent meme localement le contact socle-couverture. Dans les deux principaux secteurs mineralises, bertholene et brousse-broquies sont decrites respectivement l'albitisation d'un socle orthogneissique et celle d'une serie permo-houillere. La repartition precise des zones albitisees montre qu'elles constituent en fait les racines d'un profil d'alteration triasique, fossilise sous la couverture secondaire. A bartholene, comme a brousse-broquies, les mineralisations uraniferes sont guidees par des fractures subverticales en extension, mais se localisent exclusivement au sein de facies prealablement albitises au trias. Leur mise en place est due a l'action de circulations ascendantes dont on peut preciser l'age (environ 170 ma, jurassique moyen) et la temperature (environ 150 degres c). Une alteration supergene fini-tertiaire a sub-actuelle affecte de plus ces mineralisations. Les gisements uraniferes du rouergue apparaissent dans leur quasi totalite "lies spatialement a une discordance" (ici d'age triasique). Leur etude peut, par comparaison, eclairer d'un jour nouveau la genese des grands gisements canadiens et australiens du proterozoique qui sont a l'origine de la definition de ce type
32
AZZILEY, AZZIBROUCK GEORGES. "Sedimentologie et geochimie du francevillien b (proterozoique inferieur). Metallogenie des gisements de manganese de moanda, gabon". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13041.
Testo completo
33
Delaunay, François. "Etude de l'influence des éléments mineurs d'addition sur l'oxydation à haute température d'alliages base nickel". Rouen, 1997. http://www.theses.fr/1997ROUES029.
Testo completoAbstract (sommario):
La compréhension des phénomènes d'oxydation à haute température des alliages base nickel revêt un intérêt particulier pour l'industrie nucléaire. Les performances de ces alliages, tout comme celles des aciers, sont fortement influencées par les différents éléments mineurs d'addition. Six alliages commerciaux ont été traités entre 800°C et 1000°C sous air et étudiés à l'aide des méthodes d'analyse complémentaires suivantes : spectroscopie de photoélectrons induits par un rayonnement X, spectroscopie infrarouge à transformée de Fourier, diffraction des rayons X et microscopie électronique à balayage couplée avec un système d'analyse en énergie des rayons X émis. Les résultats obtenus mettent en évidence le rôle très important des éléments mineurs d'addition que sont le manganèse, le silicium, le titane, l'aluminium et le niobium sur les mécanismes d'oxydation. La diffusion rapide du manganèse et du titane à travers la phase rhomboédrique formée initialement, conduit à la formation d'une couche d'oxydes de structure duplex. L'oxydation intergranulaire du titane et de l'aluminium est substantielle et peut être corrélée avec l'épaisseur de la zone affectée par la déplétion en chrome dans l'alliage sous-jacent. Le silicium favorise la formation du chromite de manganèse, cependant, le développement d'une couche continue de silice à l'interface oxyde-alliage ralentit la cinétique d'oxydation. La présence de niobium semble également avoir un effet bénéfique sur la résistance à l'oxydation. La comparaison de ces résultats avec ceux obtenus sur des aciers ferritiques et austénitiques étudiés au laboratoire et avec ceux issus de la littérature permet d'apporter des informations qualitatives concernant la vitesse de diffusion des différents éléments en fonction de la matrice. Ainsi, dans les aciers ferritiques, ou les vitesses de diffusion sont plus élevées que dans les matrices austénitiques, la diffusion du titane est plus rapide que celle du manganèse. Dans les aciers austénitiques, ces deux éléments diffusent à des vitesses comparables alors que dans les alliages base nickel, le manganèse diffuse plus vite que le titane.
34
Novák, Jan. "Analýza návrhových prvků okružních křižovatek v závislosti na nehodovost". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390280.
Testo completoAbstract (sommario):
The dissertation deals with the analysis of roundabout design elements and their impact on accidents. The analysis objective was to identify the important elements of roundabouts that have impact on accidents. In order to achieve this goal, the multifactorial statistical safety assessment method was used on the basis of a representative sample of data, by developing several safety performance functions, verifying them and interpreting the result. Several design elements, which from the point of view of the traffic accident mechanism belong to the infrastructure factor, have been identified: AADT, average diameter, entrance width, entry angle, direct passage angle, location and many others. The original sample contained about 1200 roundabouts, which were reduced to 200 based on data availability. Accident frequencies were monitored between 2009 and 2016, i.e. for eight years, resulting in total 2674 roundabouts accidents. The result is an accident prediction model, developer based on roundabout approach design elements, and map of critical roundabouts, identified based on empirical Bayes estimate of accident frequency. Following approach parameters were identified: AADT, entry angle, distance between collision points, deviation of angles between approaches, presence of apron, presence of bypass, entry type, presence of pedestrian crossing and surrounding area type.
35
劉昇明. "Daily dietary intake of minor and trace elements". Thesis, 1991. http://ndltd.ncl.edu.tw/handle/72123122907956975513.
Testo completo
36
Chang, Che-Ming, e 張哲銘. "Effect of minor elements on the hot deformation behaviours of a superalloy". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/b6c5h3.
Testo completoAbstract (sommario):
碩士國立清華大學
材料科學工程學系
102
Incoloy A-286 is a Fe-Ni based superalloy and it is widely used in gas turbine industry, jet engines and other applications. Although A-286 has a long service history, the fabrication of A-286 is not without any challenges. The hot deformation property for this alloy is highly sensitive to its composition, especially the content of impurity such as sulfur (S). In present study, a batch of A-286 has suffered from cracking issue during rolling process at high temperature and detailed examinations have revealed that phenomena of liquation of Ti-rich phase induced by eutectic reaction with S appeared at grain boundary and caused intergranular fracture. To improve the hot deformation behaviors of A-286, alloy design has been performed with the minor addition of magnesium (Mg). Furthermore, its combined effect with manganese (Mn) has been examined. Experiments include tensile tests at 1050oC and 1175oC, cyclic oxidation at 900oC, detailed microstructure/fracture surfaces observations and composition analysis by OM, SEM-EDS, TEM-EDS, Auger, and EPMA. In conclusion, Mg addition can eliminate the phenomena of Ti-rich phase liquation, the high temperature deformation behaviours of A-286 can then be improved.
37
"Armenian Folk Elements in Arno Babajanian's Piano Trio in F-Sharp Minor". Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.38625.
Testo completoAbstract (sommario):
abstract: Armenian music has a rich history. It started as independent, monodic song, and succeeded in keeping its uniqueness from the influences of other countries' musical traditions. During the nineteenth century the great Armenian musicologist and composer Komitas started to travel and write down these songs from Armenian villages. Komitas, who had higher education in Western classical music, was one of the first composers to harmonize Armenian songs and sacred music using Western classical techniques. This was a milestone in the development of Armenian music. Arno Babajanian was a Soviet Armenian composer who, like Komitas, was interested in the combinations of Armenian folk and Western classical traditions. This document provides a formal and harmonic analysis of his Piano Trio in F-Sharp Minor, written in 1952. By identifying Armenian folk tunes used in his trio, I will demonstrate that Babajanian achieved interesting results by inserting exotic Armenian folk melodies, harmonies, and other elements into the Western classical sonata form. This document also points out the influence of other composers of the Soviet era on Babajanian's music. By combining Armenian folk and western classical elements in his Piano Trio, Babajanian created a piece that resonates with native Armenians and classical music lovers and deserves a place in the violin repertoire.Dissertation/Thesis
Doctoral Dissertation Music 2016
38
George, L. L. "Trace and minor elements in galena: a reconnaissance LA-ICP-MS study". Thesis, 2013. http://hdl.handle.net/2440/100088.
Testo completoAbstract (sommario):
This item is only available electronically.Many minor/trace elements can substitute into the crystal lattice of galena at various concentrations. In-situ LA-ICP-MS analysis and trace element mapping are used to obtain minor/trace element data from a range of natural galena specimens aiming to enhance understanding of the governing factors that control minor/trace element partitioning. The coupled substitution Ag+ + (Bi, Sb)3+ ↔ 2Pb2+, is confirmed by data obtained, although when Bi and/or Sb are present at high concentrations (~> 0.002 mol.%), site vacancies most likely come into play through the additional substitution 2(Bi, Sb)3+ + □ ↔ 3Pb2+. Galena is the primary host of Tl in all mapped mineral assemblages. Thallium is likely incorporated into galena along with Cu through the coupled substitution: (Ag, Cu, Tl)+ + (Bi, Sb)3+ ↔ 2Pb2+. Tin can reach significant concentrations in galena, particularly when the latter formed via metamorphic recrystallisation. Tin is concentrated in galena, likely via the substitution: Sn4+ + □ ↔ 2Pb2+, involving the creation of lattice vacancies, or Sn2+ ↔ Pb2+. Tin and In concentrations show a strong positive correlation across the sample suite indicating that the availability of these elements is intimately linked in natural systems. Cadmium and minor Hg can be incorporated into galena; the simple isovalent substitution (Cd, Hg)2+ ↔ Pb2+ is inferred. Significant oscillatory compositional zoning, and lesser sector zoning of minor/trace elements (Ag, Sb, Bi, Se, Te) is confirmed, for the first time, in galena from two epithermal ores. Zoning is attributed to slow crystal growth into open spaces within the vein at relatively low temperatures. The datasets generated increase understanding of the nature and distribution of minor/trace elements in galena, and partitioning between galena and coexisting minerals. These data have several applications in the minerals industry, particularly in studies of mineral deposit genesis, ore processing and, potentially, also in mineral exploration.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Scences, 2013
39
Lockington, J. A. K. "Trace and minor elements in sphalerite: an assessment of distributions in metamorphosed deposits". Thesis, 2012. http://hdl.handle.net/2440/92909.
Testo completoAbstract (sommario):
This item is only available electronically.Sphalerite is a common sulphide mineral and occurs in ore deposits of various types. It is the major ore mineral in the majority of Zn-Pb sulphide deposits. The emergence of precise, high-resolution microanalytical methods, such as Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS) has allowed for greater precision in the analysis of the minor and trace elemental characteristics of sulphides, including sphalerite. These methods have evolved to become valuable petrogenetic tools over the past decade. In this study Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS) has been used to analyse 19 sulphide samples from metamorphosed sphalerite-bearing deposits in Norway and Australia. The distributions of Mn, Fe, Co, Cu, Ga, Se, Ag, Cd, In, Sn, Sb, Hg, Tl, Pb and Bi have been investigated with particular attention to how concentrations of these elements vary with metamorphic grade and the extend of sulphide recrystallisation and syn-metamorphic deformation. The study has also attempted to address any possible correlations among the different elements. The results were found to indicate that trace elements which are believed to exist as micro- to nano-scale inclusions in sphalerite (such as Cu, Pb and Bi) are reduced in abundance with increasing metamorphic grade. This is due to recrystallisation resulting in these small scale inclusions being removed from the sphalerite and remobilised to form discrete minerals elsewhere. The distributions of lattice-bound elements (Mn, Fe, Cd, In, Hg) show few trends, suggesting that source and physico-chemical conditions of primary crystallisation are dominant in defining the concentrations of these elements. A moderately strong positive correlation between copper and indium concentrations was also identified, confirming previously published data
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2012
40
Potgieter, Sanja Steyn. "The determination of major, minor and trace elements in cement and cement-related materials". 2002. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001453.
Testo completoAbstract (sommario):
D. Tech. ChemistryThe cement industry plays a major role in the world economy. Analytical techniques are central to its success. Many of the techniques currently in use, mainly wet classical methods, could be improved and optimized to increase economic benefits. The aim of this study was to identify and optimized selected analytical techniques. Four analytical methods were selected: the determination of available lime in lime, Cr(VI) in cement and cement-related materials, chloride in various cementitious materials as well as minor and trace elements in cement clinker and gypsum.
41
Méndez, José Eduardo Valdez. "Numerical and experimental characterization of the interaction between major and minor axis joints". Master's thesis, 2017. http://hdl.handle.net/10316/97973.
Testo completoAbstract (sommario):
Dissertação de Mestrado em Construção Metálica e Mista apresentada à Faculdade de Ciências e TecnologiaAs ligações são uma parte essencial das estruturas metálicas. Há uma grande variedade de ligações metálicas utilizadas no sector da construção, tendo diferentes características e comportamentos mecânicos. É possível classificar as ligações de acordo com diferentes critérios e estudá-las de acordo com isso. Isto permite o estudo aprofundado das ligações que partilham caraterísticas similares, usando métodos analíticos, experimentais e numéricos.Este trabalho apresenta a caracterização experimental e numérica de cinco diferentes configurações de ligações metálicas viga-coluna com chapa de topo. Tendo em vista o estudo do efeito da interacção de esforços na alma do pilar. Os ensaios experimentais foram realizados com espécimenes de tamanho real e modelações numéricas (que correspondem às caraterísticas dos ensaios experimentais) foram realizados usando o programa de elementos finitos Abaqus.A presença de vigas nos diferentes eixos (tanto no eixo maior ou menor), dita o comportamento da junta. As juntas estão sujeitas a flexão em duas direções ortogonais, introduzindo um carregamento tridimensional à junta. As juntas são avaliadas em termos das relações momento-rotação, da resistência e da rigidez. O trabalho realizado permitiu validar os modelos numéricos com base nos ensaios experimentais e usar os primeiros para avaliar em maior profundidade o comportamento das juntas e o efeito da interação de esforços. Com isto, é possível descrever a influência entre o comportamento mecânico das juntas comparando os resultados obtidos neste projeto.
The joints are essential parts of steel structures. There is a wide variety of steel joints used in the construction sector, and they have different characteristics and mechanical behaviors. It is possible to classify the joints according to different criteria and study them accordingly. This allows the further study of joints that share similar characteristics, by using analytical, experimental and numerical methods.This work presents the experimental and numerical characterization of five different configurations of beam-to-column end-plate steel joints, regarding the study of the internal stresses interaction effect in the column web. The joint configurations are variations on the simultaneous presence of beams in a beam-to-column joint. The experimental tests were carried out with full-size specimens and the numerical modeling (which correspond to the experimental test characteristics) was made using the finite element program Abaqus.The presence of the beams in different axes (either major or minor axes) dictates the connection behavior. The connections are subjected to bending in two orthogonal directions, introducing a 3D loading to the connection. The connections are evaluated in terms of moment-rotation relations, resistance and stiffness. The performed work allowed to validate the numerical models based on the experimental tests and use the first to evaluate in more depth the joint behavior and the effect of the stress interaction. With this, it is possible to describe the influence between the mechanical behavior of the joints comparing the results obtained in this project.
42
Méndez, José Eduardo Valdez. "Numerical and experimental characterization of the interaction between major and minor axis joints". Master's thesis, 2017. http://hdl.handle.net/10316/87287.
Testo completoAbstract (sommario):
Dissertação de Mestrado em Construção Metálica e Mista apresentada à Faculdade de Ciências e TecnologiaAs ligações são uma parte essencial das estruturas metálicas. Há uma grande variedade de ligações metálicas utilizadas no sector da construção, tendo diferentes características e comportamentos mecânicos. É possível classificar as ligações de acordo com diferentes critérios e estudá-las de acordo com isso. Isto permite o estudo aprofundado das ligações que partilham caraterísticas similares, usando métodos analíticos, experimentais e numéricos.Este trabalho apresenta a caracterização experimental e numérica de cinco diferentes configurações de ligações metálicas viga-coluna com chapa de topo. Tendo em vista o estudo do efeito da interacção de esforços na alma do pilar. Os ensaios experimentais foram realizados com espécimenes de tamanho real e modelações numéricas (que correspondem às caraterísticas dos ensaios experimentais) foram realizados usando o programa de elementos finitos Abaqus.A presença de vigas nos diferentes eixos (tanto no eixo maior ou menor), dita o comportamento da junta. As juntas estão sujeitas a flexão em duas direções ortogonais, introduzindo um carregamento tridimensional à junta. As juntas são avaliadas em termos das relações momento-rotação, da resistência e da rigidez. O trabalho realizado permitiu validar os modelos numéricos com base nos ensaios experimentais e usar os primeiros para avaliar em maior profundidade o comportamento das juntas e o efeito da interação de esforços. Com isto, é possível descrever a influência entre o comportamento mecânico das juntas comparando os resultados obtidos neste projeto.
The joints are essential parts of steel structures. There is a wide variety of steel joints used in the construction sector, and they have different characteristics and mechanical behaviors. It is possible to classify the joints according to different criteria and study them accordingly. This allows the further study of joints that share similar characteristics, by using analytical, experimental and numerical methods.This work presents the experimental and numerical characterization of five different configurations of beam-to-column end-plate steel joints, regarding the study of the internal stresses interaction effect in the column web. The joint configurations are variations on the simultaneous presence of beams in a beam-to-column joint. The experimental tests were carried out with full-size specimens and the numerical modeling (which correspond to the experimental test characteristics) was made using the finite element program Abaqus.The presence of the beams in different axes (either major or minor axes) dictates the connection behavior. The connections are subjected to bending in two orthogonal directions, introducing a 3D loading to the connection. The connections are evaluated in terms of moment-rotation relations, resistance and stiffness. The performed work allowed to validate the numerical models based on the experimental tests and use the first to evaluate in more depth the joint behavior and the effect of the stress interaction. With this, it is possible to describe the influence between the mechanical behavior of the joints comparing the results obtained in this project.
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SHA, JIAN-GUO, e 沙建國. "The effects of minor elements on the laser beam welding characteristics of 304 stainless steel". Thesis, 1991. http://ndltd.ncl.edu.tw/handle/04456298891164985459.
Testo completo
44
Hsing-hui, Tsai, e 蔡幸慧. "Brahms Piano Quartet Op. 25 in G Minor, Mot. IV----A Discussion of Gypsy Music, including Elements and Style". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/19234508312454317703.
Testo completo
45
Lou, H. T., e 駱新田. "Effects of Minor Elements Pb, Bi, Sb and Ce on the Microstructures and Mechanical Propertis of Heavy Section Dutile Cast Irons". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/97038483217925245444.
Testo completoAbstract (sommario):
碩士國立臺灣大學
機械工程學系研究所
84
The effects of minor elements, i. e., Pb, Bi, and Sb, and Ce on the microstructures and mechanical properties of heavy section dutile cast irons were investigated in this study. The experimental results indicate that degenerate forms of graphite tend to precipitate in ductile iron castings that solidify over an extended period of time. Additions of small amoumts of minor elements, such as 0.005% Pb or 0.003% Bi or 0.008% Sb, result in increased nodule count and improved nodularity. However, substantial graphite deterioration occurs as the addition amounts of those minor elements become excessive, for instance 0.015% Pb, or 0.006% Bi, or 0.016% Sb. The subversive effects of Pb, Bi and Sb can be neutralized by rare earths ( Ce ) addition in appropriate ratios, i.e., Ce/Pb=0.9, Ce/Bi=1.1 and Ce/Sb=0.9. CHanges in the microstructures of heavy section ductile irons brought about by Pb additions and/or Ce neutralization exert no significant influence on both tensile and yield strengths. The is due to the fact that an improvement in both nodularity and nodule count ( in the case of a small Pb addition or Ce neutralization ) also promotes ferrite formation. These two factors counteract each other in terms of strength. However, the tensile ductility and impact values are substantially increased as the graphite nodularity and nodule count are increased. Similar results were obtained for Bi. With respect to Sb, due to its being a strong pearlite promoter, the tensile strengths tend to increase but the elongation and impact values are greatly reduced as the Sb addition amount is increased. When the harmful effect of Sb was completely neutralized by Ce, the ductility and toughness are increased significaritly, but the strength and hardness are slightly decreased.
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Mondol, Sukla. "Improving High Temperature Strength of 2219 Al Alloy by Minor Alloying Additions". Thesis, 2015. http://etd.iisc.ernet.in/2005/3755.
Testo completoAbstract (sommario):
Among Al alloys, 2219 Al alloy possesses highest strength at elevated temperatures. However, the application of this alloy is also restricted to a maximum temperature of 150°C, above which, the strengthening precipitates coarsen rapidly resulting in a steep loss in strength. In the present investigation, an attempt has been made to improve the elevated as well as the room temperature properties of commercial 2219 alloy by the addition of small amounts of Sc & Mg, Sc & Zr, and Nb & Zr, and these are designated as 2219ScMg, 2219ScZr and 2219NbZr alloys, respectively.
All the three alloys were cast in the form of strips in a water cooled copper mould using suction casting technique with a cooling rate of 102 to 103 K/s. The as-cast strips of 2219ScMg alloys were naturally aged and cold rolled by following three different routes (a) cold rolling, (b) homogenization and cold rolling and (c) hot rolling and cold rolling.
A significant improvement in strength has been achieved by all the three wrought processing routes with greater than 140 MPa increase in 0.2% proof stress at room temperature and greater than 110 MPa increase in 0.2% proof stress at 200°C as compared to 2219-T851 alloy having 0.2% proof stress of 345 MPa at room temperature and 205 MPa at 200°C. Hardness values, measured at room temperature after exposure at 200°C, remain stable up to 1000 h.
Microstructural analysis of 2219ScMg alloy reveals that Al3Sc or Al3(Sc,Zr) dispersoids form during casting and GP zones form on {100} and {111} plane during natural ageing. Subsequently, rolling introduces higher dislocation densities in the matrix. All these microstructural features contribute to the improvement of the room temperature strength of the alloy. On exposure at 200°C, GP zones transform to mainly θ′ and a few Ω precipitates. A finer, homogeneous distribution of θ′ and Ωprecipitates yields higher strength. Sc and Mg atoms are segregated at the θ′/matrix interface, which gives rise to slower growth kinetics of θ′ precipitates. As a result, the alloy exhibits better thermal stability at 200°C. For 2219ScZr and 2219NbZr alloys, the processing of the cast strip involves a two stage ageing procedure. This includes first stage ageing at 375°C for 2219ScZr alloy and at 400°C for 2219NbZr alloy. This is followed by solution treatment at 535°C for 30 minutes and second stage ageing at 200°C for both the alloys.
For 2219ScZr alloy, tensile tests performed at room temperature, 200°C and 250°C show 0.2% proof stress of 456 ± 22 MPa, 295 ± 20 MPa and 227 ± 2 MPa respectively. The alloy is found to be thermally stable at 200°C. It is found that the addition of Sc and Zr results in the formation of Al3(Sc,Zr) precipitates during ageing at 375°C. These precipitates are fully coherent with the matrix and have a significant precipitation hardening effect. They also stimulate the nucleation of θ′′ and θ′precipitates during ageing at 200°C making them finer, homogeneously distributed and thermally stable. Therefore, the strength of the alloy at ambient and elevated temperature is improved.
For 2219NbZr alloy, the tensile tests show that 0.2% proof stress is 409 ± 10 MPa at room temperature and 252 ± 22 MPa at 200°C. Microstructural observations reveal that the increase in strength is mainly due to the high volume fraction of Al3Zr precipitates, which form during ageing at 400°C, and due to the formation of θ′′ and θ′precipitates during ageing at 200°C. It is observed that Al3Zr precipitates facilitate the nucleation of θ′′ and θ′ precipitates making them finer, homogeneously distributed and thermally stable, as in the case of 2219ScZr alloy.
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Peng, Chun-Hao, e 彭俊浩. "Effect of non-equal molar AlCrFeMnNi high-entropy alloys on the precipitates and high-temperature-wear performance by addition of minor elements". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ft9cz7.
Testo completo
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"Determination of some minor elements in cement by energy dispersive x-ray fluorescence spectrometry and determination of mercury in water by static cold vapour atomic absorption spectrometry". Chinese University of Hong Kong, 1994. http://library.cuhk.edu.hk/record=b5887279.
Testo completoAbstract (sommario):
by Wong Chi Kin.Thesis (M.Phil.)--Chinese University of Hong Kong, 1994.
Includes bibliographical references (leaves 131-133).
Acknowledgement
Abstract --- p.1
General introduction --- p.4
Part I Determination of Some Minor Elements in Cement by Energy Dispersive X-Ray Fluorescence Spectrometry
Introduction --- p.7
Experimental --- p.14
Results and discussions --- p.18
Part II Determination of Mercury in Water by Static Cold Vapour Atomic Absorption Spectrometry
Introduction --- p.78
Experimental --- p.84
Results and discussions --- p.89
Conclusion --- p.130
References --- p.131
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Goso, Xolisa Camagu. "Identification of the sources of, and subsequent minimization of the uncertainties associated with the measurement of minor elements in PGM furnace matte by ICP-MS". Thesis, 2009. http://hdl.handle.net/10210/2350.
Testo completoAbstract (sommario):
M.Tech.The Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique showed very high uncertainties associated with the determination of the concentrations of minor elements in the Platinum Group Metal (PGM) smelting plant samples. This project reports on the work done for the identification of, and subsequent minimisation of the sources of uncertainties associated with the measurements of minor elements in the PGM Furnace Matte material by ICP-MS. To perform these studies, Elan 6000, Shimadzu ICPM-8500 and Finnigan Element 2 ICP-M spectrometers were employed. Synthetic Furnace Matte samples (SFMSs) were prepared and used to ascertain the uncertainties associated with the alleged sources at Mintek and Leo-Tech laboratories. The Element 2 spectrometer dominated the other two ICP-M spectrometers in terms of the accuracy for the determination of the concentrations of minor elements in SFMSs. The evidence of spectral interferences from the significant deviations in the measurement results between the isotopes of the same element was observed in the quantification of Zn, Se, Te and Sn in SFMS by the quadrupole Elan 6000 and the Shimadzu spectrometers. It also transpired that the accuracy of the quantitative determination of minor elements in the Furnace Matte (FM) matrix by ICP-MS was hampered by the matrix elements with the severity depending on the specific analyte and the make and model of the ICP-M spectrometer. The Anglo platinum FM material that was analysed in the second round robin was used as a Certified Reference Material (CRM) in the analysis of the Lonmin FM sample. It was revealed that the laboratory standard operating procedures for the preparation, dilution and subsequent analysis of the sample are potential sources of uncertainty in measurement results. The two-fold dilution of the sample for the lessening of the matrix effects was not effective. The use of multi-walled nanotubes for the alleviation of the matrix effects by removal was also not successful. Nevertheless standard addition method (SAM), combined with internal standardisation can be used as an effective calibration method in ICP-MS to achieve less matrix interfered results over the combination of the common external standardisation and internal standardisation methods.
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Qin, Guoming. "Minor element behavior in the INCO CRED process". Thesis, 2005. http://hdl.handle.net/2429/16225.
Testo completoAbstract (sommario):
In LNCO's Copper Refinery Electrowinning Department (CRED) the copper sulfide residue
containing precious metals (referred as the first stage cake), is subjected to an oxidative
pressure leach. The leach - referred as second stage leaching, produces a copper sulfate
solution and basic copper sulfate. The basic copper sulfate is releached with spent electrolyte
from copper electrowinning containing sulfuric acid to produce impure copper sulfate
solution and a precious metals residue.
A sample of first stage cake from INCO CRED was shipped to UBC and treated under
second stage leaching conditions. The minor element behavior in the process was the
objective of the study. The minor elements include cobalt, iron, arsenic, antimony, bismuth,
selenium, tellurium and tin. Four important factors that might affect the behavior of minor
elements were investigated: Cu/Acid ratio in the feed, Cu/S ratio in the feed, impurity levels
in the feed and degree of oxidation. Four series of experiments were performed with filtrate
solutions and solid residues analyzed by ICP scan for chemical compositions.
Selenium was the minor element of greatest interest due to the difficulty in removing Se from
the CRED impure leach solution. Selenium species if present will contaminate copper
cathodes and therefore must be removed. The two principal forms of selenium in the CRED
streams are believed to be selenite (SeIV) and selenate (SeVI), respectively. INCO CRED had
a great concern about selenium speciation in the second stage leaching, which will help to
understand the behavior of selenium better and remove it more efficiently. A method for
selenium analysis was developed, which was based on Atomic Fluorescence Spectrometry
with Hydride Generation (AFS-HG). A pretreatment process was applied to suit the samples
in the project and eliminate interferences in Se analysis caused by sulfate and cations. This
method was initially applied to samples generated in the UBC lab work. In addition, some
samples were taken from INCO CRED plant and analyzed by this method.Applied Science, Faculty of
Materials Engineering, Department of
Graduate