Solarzellen auf Basis von hybriden Perowskiten, wie zum Beispiel Methylammoniumbleitriiodid (CH3NH3PbI3), stellen eine der vielversprechendsten Solarzellenkonzepte dar. Dabei wurden Wirkungsgrade über 20 % gezeigt. Perowskite werden durch verschiedene lösungsbasierte Techniken abgeschieden. Daher konzentriert sich der erste Teil dieser Dissertation auf die Bildung von hybriden Perowskiten in der Lösung, während der zweite Teil der Stabilität von hybriden Perowskiten gewidmet ist. Im ersten Teil, wird die Bildung von Polyiodidplumbaten aus PbI2 in Lösung nachgewiesen. Die Bildung dieser Polyiodidplumbate konnte unabhängig von dem gewählten Lösungsmittel sowie unabhängig von der Beigabe von Methylammoniumiodid (CH3NH3I) beobachtet werden. Die Polyiodidplumbate zeigten, ähnlich wie CH3NH3PbI3, ein Photolumineszenzmaximum bei einer Wellenlänge von 760 nm, was auf einen gemeinsamen Ursprung des angeregten Zustands in PbI2-Komplexen und CH3NH3PbI3 hindeutet. Im zweiten Teil wurden darüber hinaus die Lichtbeständigkeit sowie die thermische und kompositionelle Stabilität untersucht. Die Untersuchung der thermischen Stabilität hat gezeigt, dass Tempern bei T <190 °C zu einer Verbesserung der Morphologie und der optoelektronischen Eigenschaften führt. Oberhalb einer Temperatur von 190 °C kam es dabei zur Zersetzung des Materials. Die Stabilität der Komposition wurde anhand von CsPb(I[1-x]Br[x])3-Perowskiten untersucht. Die Herstellung von Perowskiten mit einer großen Bandlücke war zunächst nicht möglich, da es bei den dafür notwendigen Kompositionen (0,3<x<1) zur Phasentrennung kommt. Im Gegensatz dazu konnte durch den Zusatz von Ethylendiammoniumdiodid (EDDI) zu CH3NH3PbI3 die Bandlücke zwischen 1,6 und 1,8 eV variiert werden. Die Lichtstabilität von CH3NH3PbI3, CH(NH2)2PbI3 sowie gemischt Perowskiten wurde mittels in-situ Infrarotspektroskopie analysiert. Die Zersetzung des Materials war durch die lichtinduzierte Spaltung der N-H-Bindungen bei hv ≥ 2,72 eV gekennzeichnet. / Hybrid perovskites such as methylammonium lead iodide, CH3NH3PbI3, are one of the most promising absorber materials for photovoltaic energy conversion with demonstrated power conversion efficiencies beyond 20 %. In addition, hybrid perovskites can be deposited by various solution-based fabrication techniques. Therefore, the first part of this dissertation is focused on the formation of hybrid perovskites in the precursor solution, while the second part is dedicated to the study of the stability of hybrid perovskites. In the first part of this thesis, the formation of polyiodide plumbates between molecules of PbI2 was detected. Importantly, the formation of polyiodide plumbates was observed independently of the solvent choice or the presence of CH3NH3I. The polyiodide plumbates exhibited a photoluminescence peak located at 760 nm, similarly to CH3NH3PbI3, which suggests a common origin of the excited state in PbI2 complexes and CH3NH3PbI3. In the second part of this thesis, the thermal, compositional, and photostability of perovskite thin films were evaluated. The study of the thermal stability has shown that post-annealing at T < 190 °C leads to the improvement of morphology and optoelectronic properties. Above 190 °C, CH3NH3PbI3 was found to degrade. Next, the compositional stability of mixed CsPb(I[1-x]Br[x])3 perovskites was investigated. A fundamental miscibility gap between 0.3 < x <1 was demonstrated, that impedes the preparation of high band-gap perovskites. To overcome this intrinsic instability, a new approach for band-gap engineering was developed. An addition of ethylenediammonium diiodide (EDDI) allowed to alter the band gap of CH3NH3PbI3 from 1.6 to 1.8 eV. Finally, the influence of light on the stability of hybrid perovskites was studied. A degradation of CH3NH3PbI3, CH(NH2)2PbI3, as well as mixed perovskites, was observed through photo-dissociation of N-H bonds with hν ≥ 2.72 eV by means of in-situ Fourier-transform infrared spectroscopy.

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This master thesis had been created at the instigation of Skoda Auto. a.s. tool design department, which designed a new concept of the diecast mold. For this new concept of construction mold was requested to describe its strain-stress behaviour. The main goal of this thesis was to run s-s analysis. According to results of s-s analysis the potentially risky location had been found and the recommendation of the design improvement had been made. The problem has been solved by Finite Element Method in software ANSYS Workbench. The output of the work is mainly used as a basis for the design of high-pressure casting molds of S. A. a.s.

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Syftet för det här examensarbetet var att praktiskt reducera ställtiden på enbefintlig produktionslinje på Ruukki i Halmstad. Vid tiden då författarna togkontakt med företaget var den nuvarande ställtiden alldeles för lång och långtifrån optimal. I samband med projektets start gjordes det ett antal avgränsningaranpassat till den tiden som fanns tillgänglig.Tillvägagångssättet och metodiken till lösningen bakom ställtidsproblematikenföljer Shigeo Shingos Single Minute Exchange of Die (SMED), där har författarnautfört analyser i form av iakttagelser och tidtagning. Upptäckterna som gjordesunder analys samt implementering var att även om SMED är en direkt metodik förställtidsreduktion finns det andra faktorer som kan motverka implementeringensamt dess goda resultat. Dessa faktorer som påvisades under projektets gång varbland annat de mänskliga aspekterna och den bakomliggande företagskulturen iorganisationen. SMED är en av stöttepelarna för en implementering av Just-In-Time (JIT) som i sig är en viktig beståndsdel av Lean Production.Examensarbetet resulterade i framtagning av en rutin som därefter visualiserades iform av en arbetsmanual. Rutinen testkördes och påvisade gott resultat i form avkortare ställtid.

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Changes in large-scale vegetation structure triggered by processes such as deforestation, wildfires, and tree die-off alter surface structure, energy balance, and associated albedo-all critical for land surface models. Characterizing these properties usually requires long-term data, precluding characterization of rapid vegetation changes such as those increasingly occurring in the Anthropocene. Consequently, the characterization of rapid events is limited and only possible in a few specific areas. We use a campaign approach to characterize surface properties associated with vegetation structure. In our approach, a profiling LiDAR and hemispherical image analyses quantify vegetation structure and a portable mast instrumented with a net radiometer, wind-humidity-temperature stations in a vertical profile, and soil temperature-heat flux characterize surface properties. We illustrate the application of our approach in two forest types (boreal and semiarid) with disturbance-induced tree loss. Our prototype characterizes major structural changes associated with tree loss, changes in vertical wind profiles, surface roughness energy balance partitioning, a proxy for NDVI (Normalized Differential Vegetation Index), and albedo. Multi-day albedo estimates, which differed between control and disturbed areas, were similar to tower-based multiyear characterizations, highlighting the utility and potential of the campaign approach. Our prototype provides general characterization of surface and boundary-layer properties relevant for land surface models, strategically enabling preliminary characterization of rapid vegetation disturbance events.

Master of Arts / Department of Modern Languages / Jennifer Drake Askey / When Robert Musil saw his book, Die Verwirrungen des Zöglings Törless, published, he could not have seen the coming of fascist dictatorships. Despite this, two of Musil’s characters display characteristics that are hauntingly similar to characteristics common in the fascist Nazi movement in Germany and Austria, as well as protofascist groups such as the German Freikorps. By examining the characters of Beineberg and Reiting as well as their world in Die Verwirrungen des Zöglings Törless through the lens of thinkers such as Theodor Adorno and Klaus Theweleit, one can find many similarities between Musil’s characters and the fascists of the coming years. Although Beineberg and Reiting cannot take Adorno’s F-scale, which measures the authoritarian personality of individuals, there are many instances in which these characters’ actions and the F-scale overlap. One also discovers striking similarities between the tendencies of Musil’s characters and the fascistic tendencies of the Freikorps and other groups described in Klaus Theweleit’s book, Male Fantasies.

<p>Aluminum-Silicon (Al-Si) alloys are often preferred in the die casting industry due to excellent castability, high strength, corrosion resistance and low cost. Commonly, iron (Fe) is alloyed with the alloys to prevent die soldering. However, the addition of Fe in most of Al-Si alloys leads to formation of the intermetallic β-AlFeSi. The β-AlFeSi is harmful to the alloy structural integrity due to its needle-like morphology that creates stress concentration at the microscopic level. The phase presence is unfavorable to the mechanical properties and significantly reduces the elongation of the alloys. This research attempted to find viable way to control the morphology and formation of the β-AlFeSi phase.</p> <p>Thermodynamic simulations were done to investigate the sequence of intermetallic formation and other phases at different alloy compositions. The analysis of solidification paths of different alloys provided the correlation between the phase formation sequence and the fraction of the β-AlFeSi phase. The analysis also identified the feasible region of alloy design for minimizing the β-AlFeSi formation. Based on the thermodynamics simulation analysis, five alloys of different compositions were designed to validate the finding of the simulation. </p> <p>The tensile test results of the alloys indicated that lowering the Fe content increases the elongation of the alloy. The results also showed that elongation was reduced with the increase of Si level due to the formation of eutectic Silicon. The change of both Fe and Mn did not significantly affect the mechanical property of the alloy when the ratio of Fe to Mn was constant. Microscopic analysis showed that lowering the Fe level had effectively altered the morphology of the β-AlFeSi needle like structure. The β-AlFeSi was found to be smaller in terms of size when Fe is lower, subsequently reducing the probability of β-AlFeSi phase to be stress riser and crack initiation. </p> <p>The influence of heat treatment to the mechanical property of the alloys was also studied. The mechanical result on the heat-treated samples indicated that heat treatment is a viable method to improve the elongation property of the alloy. Microscopic observations showed that the β-AlFeSi phase was broken into shorter structures over the solution heat treatment process, resulting in better elongation. </p>

Degree awarded with distinction on 11 December 1997 'n Verhandeling ingelewer ter voldoening aan die vereistes vir die graad Magister Artium in die Departement van Afrikaans en Nederlands by die Universiteit van die Witwatersrand. Johannesburg, 1997 / This dissertation investigates the canonized criticism on Etienne Leroux's Sewe dee by die S'ilbersteins (1962) from the time of the novel's publication up to the 1980's. The most important analytical strategies that were implemented in this period become, in themselves, the topic of research. The study at hand claims that the allegorical structure of the novel, wi th its subsequent distinction between surface and substructure leads to irreconcilable re&dfngs. The critics either link the view of life presented b~ the novel to a limited number of imtedded fields of reference, or they present all of these fields without questioning any conflicting claims to truth. In this dissertation the novel is approached from an existentialist perspective from which all claims to truth are relativised, and the focus shifts to the narrative itself. This reading strategy departs to a large extent from existing approaches that concentrate on the substructure.