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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Geneze Au-Sb mineralizace na ložisku Krásná Hora / Genesis of Au-Sb ores at the Krásná Hora deposit

Němec, Matěj January 2014 (has links)
Ore deposits of the Krásná Hora ore district are the main representative of the Sb-Au mineralization in the Czech Republic. It can be classified genetically as epizonal subtype of orogenic gold deposits. Spatially and partly temporally are associated with the intrusion of the Central Bohemian Pluton. The ore bodies are related to quartz veins that follow the course of E-W striking lamprophyre dykes, which are usually heavily crushed and altered. Ore shoots with massive stibnite are located mainly at the intersections of these E-W trending veins with the NW-SE striking tectonic fault zones. Au-Sb ores at Krásná Hora ore district formed in an area of repeatedly activated fault zones. Three generations of hydrothermal quartz were identified on microscopic scale. Earliest quartz (Qtz1), which was considered in the literature auriferous originated from low-salinity H2O - CO2 fluids at ~350 řC and at a depth of about 5 km. The younger quartz (Qtz2) originated at lower temperatures of about 260 řC and lower depth of about 3-4 km from low/saline aqueous fluids. Both older (Qtz1) and younger quartz (Qtz2) are not auriferous. The gold is associated with younger paragenetic formation (Anti + Au + Cc + Qtz3) that fills in intergranular spaces and fractures in Qtz1 and Qtz2 . Due to the partial exhumation of the...
12

Chemimus hydrotermálního křemene z Au ložiska Mokrsko-západ stanovený metodou LA-ICP-MS / Chemistry of hydrothermal quartz from the Mokrsko-West gold deposit determined by the LA-ICP-MS method

Štrba, Martin January 2016 (has links)
The Mokrsko-West deposit, situated about 20 km south from Prague, is one of the most important gold deposits in the Bohemian Massif. We can find hydrothermal quartz veins in two types of host rocks: tonalite in the Central Bohemian Plutonic Complex (CBPC) and amphibolite in the Jílové Belt (JB). A several generations of the quartz veins with different mineralization were found in the deposit. This study has several objectives. At first, it determines and compares the chemistry of quartz samples from different generations of hydrothermal veins. In addition, this work describes the distribution of the most important trace elements. Lastly, the work compares the potential differences in the chemistry of samples from the different host rocks (CBPC and JB). With the use of the LA-ICP-MS, 16 quartz samples from the Mokrsko-West deposit were analysed. Finally, 101 analyses were realized. From the analysed trace elements, the most important were Li, Mg, Al, Ca, Fe, Cu, Zn, As, Sb and Pb. Aluminium affects the concentration of the most of analysed trace elements. Positive correlation between Al and the other metals was also found. The samples with high Al content also showed high concentrations of other metals (Fe, Cu, Zn, Pb) and As. Samples with lower Al content showed lower concentration of other metal...
13

Zlaté fólie z Borqu - ikonografická a náboženská analýza / Golden foils from Borg - iconographical and religious analysis

Gorroňová, Marianna January 2011 (has links)
5A Abstract This work gives the analysis of iconographic elements which are found on five gold foils. These foils depict two figures which look at each other from their profile. Foils were found in the foundations of the chieftain house in Lofot's islands in Northern Norway, which is from the Migration to the Viking period. For the reason of analysis the author demonstrates three main groups of gold objects - gold bracteates, gold foils and one medallion. On these objects we can find a pair of two figures and these objects were found in Scandinavia. The author presents here the context of such finds, iconographic elements and academic interpretations of the depiction. Author compares the elements such as type of foil, appearance of eyes, posture of man and woman, their dress and haidress with 91 foils from Scandinavia, and also with bracteates and other objects. She notices the partial concordance among these elements and the other objects and she seeks the iconographic essence and function of each foil from Borg which is later confronted with the theories of the influence of religion. Because of lack of attributes on the foils, the author's assumption is that there is no general depiction of gods on the foil. On the other hand, each foil has its own story showing people from their common life. According to...
14

Analýza trhu netradičných aktív (zlato, komodity). / Market analysis of unconventional assets (gold, commodities).

Gáll, Michal January 2010 (has links)
The main intention of this thesis is to provide theoretical and practical insight on commodity markets, specifically on gold and silver markets. The introductory section defines the basic characteristics and relationships between commodity and financial markets.The second section describes in detail the fundamentals of commodity markets. From a view on history, definition and distribution of basic commodities, it specifies the largest operators organizing trade with commodities. The last sub chapter of the second section is a description of the most popular ways of investing in commodities. In the third section, the content of the work reaches its core -- an analysis of the gold market. The first chapter of this section gives a picture of the general determinants of demand, supply and price of gold. The following analytical chapter discusses these essential characteristics from a dynamic perspective -- the development over time. Based on the dependencies and calculations, the work analyzes the rate of return and risk of gold and compares them with alternative investments. Final passage of the third section brings the specific investment opportunities in gold. In particular, for their inclusion in the core group of precious metals, as in the case of gold, the fourth section is devoted to the definition a marginal nature of the silver market.
15

Investiční zlato - IT podpora / Gold investment - IT support

ZAHOŘ, Zdeněk January 2011 (has links)
This thesis is about the investigation of the prediction with help of artificial neural networks. It contrasts other papers considering similar topic. This work is focused on the data collected to predict future outcomes. The data specifically deals with gold capital. It is possible to buy gold via the internet in a form of gold bars. The dealers themselves state that the price of gold is derived via the global prize index of gold and from the current value converted to the Czech Koruna rate of exchange. The aim of this work is to consider price forecast correlating input data. To achieve the desired outcome a system for the data collection, processing, and visualization has been designed. A system dealing with price prediction has been developed to show the accuracy of the results obtained.
16

Komoditmé futures na drahé kovy / commodity futures on precious metals

Schwartz, Peter January 2011 (has links)
The aim of the thesis is to clarify the importance of diversifying investment portfolios with the help of precious metals at the present time and to analyze the fluctuation of precious metals market in terms of demand, supply and price developments. The core of the thesis focuses on analysis of the market of precious metals from 1998 to 2011 The used work method is comparison of precious metals between themselves and the world stock indices, the method of analysis in separate calculations of indicators, the method of deduction from the results of calculations.
17

Prognóza vývoje trhu zlata / Gold Market Trend Forecast

Šimek, Jan January 2018 (has links)
The diploma thesis deals with econometric modelling and gold price forecast. A key factor is the multiple regression model and the ARIMA model. The first part of the diploma thesis contains a theoretical basis. The analytical part deals with modelling of gold market price and subsequent forecasting. Statistical and econometric verification using statistical methods play a very important role. The last part summarizes the results and makes suggestions for improvement.
18

Modifikace povrchu nanokapkami ovládanými elektronovou pinzetou / Surface modification by nano-droplets controlled by electron tweezers

Dao, Radek January 2020 (has links)
This master's thesis is focused on the study of the consequences of electron beam induced motion of Au-Ge alloy nanodroplets on germanium surface. The text consists of two parts. The theoretical part gives an overview of measurement and fabrication techniques used for the experiments. The description of these techniques is mainly focused on topics needed to understand the ideas behind the experiments and their results. The topics covered here are the Atomic Force Microscopy, Scanning Electron Microscopy and Electron Beam Lithography. These are followed by an introduction to the gold-germanium material system and the movement of Au-Ge alloy nanodroplets. The practical part gives a roughly chronological guide throughout the whole experimental process, including the search for a suitable sample fabrication method, the surface modification itself and its measurement. Temperature calibration of the heating system is also mentioned.
19

Aplikace transmisní elektronové mikroskopie s vysokým rozlišením pro strukturní analýzu nanovláken / Application of high resolution transmission electron microscopy for structure analysis of nanowires

Kachtík, Lukáš January 2016 (has links)
This diploma thesis deals with the structural analysis of semiconductor nanowires by transmission electron microscopy. The construction of microscope is introduced together with its basic imaging modes and with the function of each construction element in these modes. In the experimental part the results of analysis of several germnaium nanowires are discussed, with emphasis on their crystallographic structure and orientation.
20

Elektrohemijsko taloženje niobijuma iz fluoridnih rastvora i hloroaluminatnih rastopa na staklastom ugljeniku, platini i zlatu / Electrochemical deposition of niobium from fluoride solution and chloroaluminate melts on glassy carbon, platinum and gold

Vukićević Nataša 18 May 2017 (has links)
<p>Cilj ovog rada bio je da se ustanovi da li dolazi do elektrohemijskog taloženja&nbsp; niobijuma i aluminijuma iz hloroaluminatnih rastopa obogaćenih niobijumom na podlogama od staklastog&nbsp; ugljenika, platine i zlata. Nadalje, ako dolazi do rečenog&nbsp; taloženja, da li pri tome dolazi i do formiranja legura niobijuma sa izabranim podlogama kao i da li dolazi do formiranja legura niobijuma sa zajednički taloženim aluminijumom. I na kraju,&nbsp; cilj je&nbsp; bio da se navedeni fenomeni ostvare na &scaron;to nižim temperaturama.</p><p>Nb&nbsp; i&nbsp; Al&nbsp; su elektrohemijski taloženi na staklastom ugljeniku, platini i zlatu pri 200&nbsp; &deg;C, pod atmosferom argona, iz rastopa napravljenog od ekvimolarne sme&scaron;e AlCl<sub>3</sub> + NaCl kome&nbsp; je dodat niobijum.</p><p>U istraživanjima su kori&scaron;ćene: linearna&nbsp; i&nbsp; ciklička voltametrija, metoda potenciodinamičke polarizacione krive, metoda &bdquo;otvorenog kola&ldquo;,&nbsp; hronoamperometrija,&nbsp; SEM,&nbsp; EDS, AFM&nbsp; i XRD analiza.</p><p>Elektrohemijsko taloženje Nb i Al iz primenjenih rastopa pri potpotencijalima uočeno je na podlozi od zlata. Taloženje niobijuma pri potpotencijalima na zlatu je novost, a taloženje Al na zlatu pri&nbsp; potpotencijalima poznato je od ranije. Elektrotaloženje&nbsp; Al&nbsp; i&nbsp; Nb&nbsp; iz primenjenih rastopa pri potpotencijalu na zlatu prethodi procesima elektrotaloženja niobijuma i aluminijuma pri natpotencijalima.&nbsp; Rezultat ovih procesa su Nb/Au i Al/Au legure nastale zajedničkim taloženjem i interdifuzijom istaloženog Nb, odnosno&nbsp; Al i podloge&nbsp; -&nbsp; zlata (AlAu,&nbsp; AlAu<sub>2</sub> , AlAu<sub>4</sub>, AlNb<sub>2</sub> , AlNb<sub>3</sub> , Au<sub>2</sub>Nb, Au<sub>2</sub>Nb<sub>3</sub> , AuNb<sub>3</sub> , AlNb<sub>3</sub>).</p><p>Elektrohemijsko taloženje Nb iz primenjenih rastopa pri potpotencijalima uočeno je na platini i prethodi procesima elektrotaloženja&nbsp; Nb&nbsp; i&nbsp; Al. Rezultat su formirane Nb/Pt legure nastale interdifuzijom&nbsp; istaloženog Nb i podloge&nbsp; -&nbsp; platine (Nb<sub>3</sub>Pt). Pri natpotencijalima aluminijuma na&nbsp; platini dolazi do taloženja metalnog niobijuma, metalnog aluminijuma i zajedničkog taloženja Nb i Al. Kao posledica&nbsp; ovih procesa dolazi i do formiranja legura (AlNb<sub>3</sub>, Al<sub>3</sub>Pt<sub>5</sub> ,&nbsp; Nb<sub>3</sub>Pt).</p><p>Elektrohemijsko taloženje niobijuma iz primenjenih rastopa na izabranim podlogama odigrava se na potencijalima koji su pozitivniji od potencijala&nbsp; elektrotaloženja aluminijuma.</p><p>Sve dobijene legure formirane su pri temperaturi od 200 &deg;C &scaron;to je nekoliko stotina stepeni niže od odgovarajućih temperatura potrebnih da se formiraju termičkim putem.&nbsp;</p> / <p>The aim of this study was to establish electrodeposition of niobium and aluminium from chloroaluminate melt (AlCl<sub>3</sub> + NaCl) enriched with niobium onto gold, platinum and glassy carbon substrates. Furthermore, if such deposition is shown to occur,&nbsp; to&nbsp; assess if it can lead to formation ofniobium alloys with chosen substrates or&nbsp; formation of Nb/Al alloys as a result of codeposition. And finally, if the deposition is indeed confirmed,&nbsp; to&nbsp; establish the lowest operational temperature at which it is possible.</p><p>Niobium and aluminium were electrodeposited onto glassy carbon, gold and platinum at&nbsp; 200 &deg;C, under an argon atmophere&nbsp; from the melt made of&nbsp; equimolar mixture AlCl<sub>3</sub> + NaCl with niobium being added.</p><p>Research methods used were:&nbsp; cyclic voltammetry, potentiodynamic polarization curves, &quot;open circuit&rdquo;, chronoamperometry,&nbsp; SEM,&nbsp; EDS, AFM and&nbsp; XRD&nbsp; analysis. Underpotential deposition of&nbsp; Nb&nbsp; and Al&nbsp; from the melt onto gold substrate was observed. Of the two, niobium deposition is a novelty, while alumininum deposition has been previously studied.&nbsp; Underpotential deposition of&nbsp; NB and Al onto gold from given melt precedes the overpotential deposition of aluminium and niobium onto gold. The result of these processes are Nb/Au and Al/Au alloys formed by codeposition of the two metals&nbsp; and&nbsp; interdiffusion between the Nb and Al deposits and the substrate -gold (AlAu, AlAu<sub>2</sub>, AlAu<sub>4</sub>, AlNb<sub>2</sub>, AlNb<sub>3</sub>,&nbsp; Au<sub>2</sub>Nb, Au<sub>2</sub>Nb<sub>3</sub>, AuNb<sub>3</sub>, AlNb<sub>3</sub>). Underpotential deposition of niobium onto platinum from used melts was recorded and it precedes the&nbsp; processes of overpotential deposition of niobium and aluminium. The result is formation of Nb/Pt alloys as a consequence of&nbsp; interdiffusion between the substrate and the deposited Nb (Nb<sub>3</sub>Pt). The potentials more negative than the aluminium deposition potential in the used system lead to deposition of niobium and aluminium&nbsp; individually and jointly. Thus, a number of alloys are formed (AlNb<sub>3</sub>, Al<sub>3</sub>Pt<sub>5</sub>, Nb<sub>3</sub>Pt).&nbsp; Niobium electrodeposition onto chosen substrates from the melt applied takes place at potentials which are more positive than the potential of electrodeposition of aluminium. Formation of&nbsp; the&nbsp; obtained alloys occurred at a temperature of 200 &deg;C which is several hundred degrees lower than the temperatures needed for their formation by thermal methods.</p>

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