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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.
321

Copper Mineralogy in the Oxide Zone of the Lone Star Porphyry Copper Deposit, Eastern Arizona

Selck, Jeff G. 01 December 2017 (has links)
The Lone Star porphyry copper deposit in the Safford District of southeastern Arizona was discovered in the late 1800's but never mined on a large scale. In addition to typical copper oxide species such as chrysocolla, the upper part of the deposit has zones of mineralization in which the chemical assays of core samples have higher amounts of copper than can be visually assigned to the observed copper-bearing minerals. The goal of this study is to identify the Cu-bearing minerals, which is crucial because the efficiency of the extraction processes is strongly dependent upon the mineralogy. Samples from seven cores with a range of copper contents and observed copper minerals were collected for analysis. Elemental compositions have been determined by X-ray fluorescence spectrometry and show a large variability in copper content (ranging from 360 ppm to 4.7 wt. %). Mineral assemblages were determined by optical microscopy, energy dispersive spectroscopy on the scanning electron microscope, and X-ray diffraction analysis and show varying concentrations of possible Cu-hosting minerals such as chlorite, biotite, iron oxides/hydroxides, and clay. Copper element maps were created for selected samples using an electron microprobe and areas of elevated copper concentration were more closely mapped with quantitative analyses taken of many points. This identified some common copper minerals that were simply too small to be seen in hand sample. However, several other minerals also contain high concentrations of Cu including chlorite and biotite (up to 19.3 wt. % CuO), iron oxides/hydroxides (up to 5.2 wt. % CuO), and clay (up to 7.3 wt. % CuO). While it has been determined that there is copper substitution into the structure of these minerals, transmission electron microscope analysis shows some of the copper in the chlorite and biotite is in native Cu blebs between the phyllosilicate sheets. The iron oxides and hydroxides are nanometer-sized particles with large surface areas for adsorption of copper. This presents a multi-phase system of copper minerals that cannot be seen during normal core logging. The presence of ore-grade concentrations of copper in the oxidized zone is likely due to insufficient acid production, as Lone Star is a sulfur-poor deposit, and the neutralizing effect of the andesite that hosts the deposit.
322

Karoserie sportovního automobilu / Sport car body

Janda, Tomáš January 2011 (has links)
The master´s thesis is focused on construction of one-man car body of sports car. Work contains aerodynamic analysis of car body too and optimization of the CAD model.
323

Star – Superstar – Megastar. Steigerungsformen eines vielschichtigen Sachverhalts

Mehner, Klaus 01 September 2020 (has links)
No description available.
324

Der Musikstar und seine biographische Konstruktion im interkulturellen Vergleich

Koch, Lars-Christian 01 September 2020 (has links)
No description available.
325

Der Musikstar und sein Publikum

Roch, Eckhard 01 September 2020 (has links)
No description available.
326

Castingshow- Teilnehmer als Stars? Sozialpsychologische Annäherungen an ein Zeitgeistphänomen

Lothwesen, Kai Stefan, Müllensiefen, Daniel 01 September 2020 (has links)
No description available.
327

Disentangling star formation and AGN activity in the GAMA (G23) region

January 2021 (has links)
Philosophiae Doctor - PhD / Observations of galaxies at di↵erent wavelengths have shaped our understanding of their formation and evolution through time. The commonly derived parameters, such as stellar mass and star formation rate (SFR), rely on the assumption that the radiation received is exclusively generated by the stars within the galaxy. This assumption is true for pure star-forming (SF) galaxies, but not in the presence of an active galactic nucleus (AGN). AGNs are structures that also radiate in the full electromagnetic spectrum, inducing additional flux to that emitted by stars. Their small sizes in comparison to the host galaxy (⌧1 %) generally make them invisible in galaxy images. AGNs come in many variations making the most powerful (e.g., quasi-stellar objects) easily identifiable, whereas others with much weaker signatures can be hidden in the total emission from the host. Therefore it is imperative to find accurate methods to separate and study the properties of AGNs versus pure SF galaxies.
328

BUILDING A STORY USING SOCIAL MEDIA - A CASE STUDY OF THE BAND GHOST

Ågren, Pauline January 2019 (has links)
This study examines how a music band can manage to build an image and story using social media platforms after the infamous break of the golden era. To put it further into perspective, the second part of the study focuses on the fans’ connection to the band and how they use social media themselves. The purpose of this study is, through interviews, qualitative content analysis and rhetorical analysis, to explore how a band successfully use social media to keep their fans’ anticipation alive. To explore my purpose, I have conducted and analysed qualitative interviews. In the analysis section, the data has been interpreted in relation to theories of star image, participatory fandom and the live experience as well as compared to previous research while connecting my own analysis to it. The study discusses tendencies shown in the results when analysing posts from Ghost’s official Facebook page, as well as how participatory fandom as we know it may be at risk, as social media giants keep growing and eliminating other forums that have been vital to fans.
329

Analysis of Star Identification Algorithms due to Uncompensated Spatial Distortion

Brätt, Steven Paul 01 May 2013 (has links)
With the evolution of spacecraft systems, we see the growing need for smaller, more affordable, and robust spacecrafts that can be jettisoned with ease and sent to sites to perform a myriad of operations that a larger craft would prohibit, or that can be quickly manipulated from performing one task into another. The developing requirements have led to the creation of Nano-Satellites, or CubeSats. The question then remains, how to navigate the expanse of space with such a minute spacecraft? A solution to this is using the stars themselves as a means of navigation. This can be accomplished by measuring the distance between stars in a camera image and determining the stars' identities. Once identified, the spacecraft can obtain its position and facing. A series of star identification algorithms called Lost in Space Algorithms (LISAs) are used to recognize the stars in an image and assess the accuracy and error associated with each algorithm. This is done by creating various images from a simulated camera, using a program called MATLAB, along with images of actual stars with uncompensated errors. It is shown how suitable these algorithms are for use in space navigation, what constraints and impediments each have, and if low quality cameras using these algorithms can solve the Lost in Space problem.
330

Error Modeling and Analysis of Star Cameras for a Class of 1U Spacecraft

Fowler, David M. 01 May 2013 (has links)
As spacecraft today become increasingly smaller, the demand for smaller components and sensors rises as well. The smartphone, a cutting edge consumer technology, has impressive collections of both sensors and processing capabilities and may have the potential to fill this demand in the spacecraft market. If the technologies of a smartphone can be used in space, the cost of building miniature satellites would drop significantly and give a boost to the aerospace and scientific communities.Concentrating on the problem of spacecraft orientation, this study sets ground to determine the capabilities of a smartphone camera when acting as a star camera. Orientations determined from star images taken from a smartphone camera are compared to those of higher quality cameras in order to determine the associated accuracies. The results of the study reveal the abilities of low-cost off-the-shelf imagers in space and give a starting point for future research in the field.The study began with a complete geometric calibration of each analyzed imager such that all comparisons start from the same base. After the cameras were calibrated, image processing techniques were introduced to correct for atmospheric, lens, and image sensor effects. Orientations for each test image are calculated through methods of identifying the stars exposed on each image. Analyses of these orientations allow the overall errors of each camera to be defined and provide insight into the abilities of low-cost imagers.

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