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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.
51

Study of macroscopic and microscopic homogeneity of DEPFET X-ray detectors / Untersuchung der makroskopischen und mikroskopischen Homogenität von DEPFET-Röntgendetektoren

Bergbauer, Bettina 15 January 2016 (has links) (PDF)
For the X-ray astronomy project Advanced Telescope for High ENergy Astrophysics (Athena) wafer-scale DEpleted P-channel Field Effect Transistor (DEPFET) detectors are proposed as Focal Plane Array (FPA) for the Wide Field Imager (WFI). Prototype structures with different pixel layouts, each consisting of 64 x 64 pixels, were fabricated to study four different DEPFET designs. This thesis reports on the results of the electrical and spectroscopic characterization of the different DEPFET designs. With the electrical qualification measurements the transistor properties of the DEPFET structures are investigated in order to determine whether the design intentions are reflected in the transistor characteristics. In addition, yield and homogeneity of the prototypes can be studied on die, wafer and batch level for further improvement of the production technology with regard to wafer-scale devices. These electrical characterization measurements prove to be a reliable tool to preselect the best detector dies for further integration into full detector systems. The spectroscopic measurements test the dynamic behavior of the designs as well as their spectroscopic performance. In addition, it is revealed how the transistor behavior translates into the detector performance. This thesis, as the first systematic study of different DEPFET designs on die and detector level, shows the limitations of the current DEPFET assessment methods. Thus, it suggests a new concise characterization procedure for DEPFET detectors as well as guidelines for expanded testing in order to increase the general knowledge of the DEPFET. With this study of four different DEPFET variants not only designs suitable for Athena mission have been found but also improvement impulses for the starting wafer-scale device production are provided.
52

Study of macroscopic and microscopic homogeneity of DEPFET X-ray detectors

Bergbauer, Bettina 17 December 2015 (has links)
For the X-ray astronomy project Advanced Telescope for High ENergy Astrophysics (Athena) wafer-scale DEpleted P-channel Field Effect Transistor (DEPFET) detectors are proposed as Focal Plane Array (FPA) for the Wide Field Imager (WFI). Prototype structures with different pixel layouts, each consisting of 64 x 64 pixels, were fabricated to study four different DEPFET designs. This thesis reports on the results of the electrical and spectroscopic characterization of the different DEPFET designs. With the electrical qualification measurements the transistor properties of the DEPFET structures are investigated in order to determine whether the design intentions are reflected in the transistor characteristics. In addition, yield and homogeneity of the prototypes can be studied on die, wafer and batch level for further improvement of the production technology with regard to wafer-scale devices. These electrical characterization measurements prove to be a reliable tool to preselect the best detector dies for further integration into full detector systems. The spectroscopic measurements test the dynamic behavior of the designs as well as their spectroscopic performance. In addition, it is revealed how the transistor behavior translates into the detector performance. This thesis, as the first systematic study of different DEPFET designs on die and detector level, shows the limitations of the current DEPFET assessment methods. Thus, it suggests a new concise characterization procedure for DEPFET detectors as well as guidelines for expanded testing in order to increase the general knowledge of the DEPFET. With this study of four different DEPFET variants not only designs suitable for Athena mission have been found but also improvement impulses for the starting wafer-scale device production are provided.
53

Optimization of rectifiers for aviation regarding power density and reliability

Liebig, Sebastian 28 November 2014 (has links)
The intentions of the so-called "More Electrical Aircraft" (MEA) are higher efficiency and lower weight. A main topic here is the application of electrical instead of hydraulical, pneumatical and mechanical systems. The necessary power electronic devices have intermediate DC-links, which are typically supplied by a three-phase system with active B6 and passive B12 rectifiers. A possible alternative is the B6 diode bridge in combination with an active power filter (APF). Due to the parallel arrangement, the APF offers a higher power density and is able to compensate for harmonics from several devices. The use of the diode bridge rectifier alone is not permitted due to the highly distorted phase current. The following investigations are dealing with the development of an active power filter for a three-phase supply with variable frequency from 360 to 800 Hz. All relevant components such as inductors, EMC-filters, power modules and DC-link capacitor are designed. A particular focus is put on the customized power module with SiC-MOSFETs and SiC-diodes, which is characterized electrically and thermally. The maximum supply frequency slope has a value of 50 Hz/ms, which requires a high dynamic and robustness on the control algorithm. Furthermore, the content of 5th and 7th harmonics must be reduced to less than 2 %, which demands a high accuracy. To cope with both requirements, a two-stage filter algorithm is developed and implemented in two independent signal processors. Simulations and laboratory experiments confirm the performance and robustness of the control algorithm. This work comprehensively presents the design of aerospace rectifiers. The results were published in conferences and patents. / Hauptziele des sogenannten "More Electrical Aircraft" (MEA) sind Effizienzerhöhung und Gewichtseinsparung. Ein Schwerpunkt hierbei ist die Nutzung von elektrischen statt hydraulischen, pneumatischen und mechanischen Systemen. Die notwendigen Leistungselektroniken haben DC-Zwischenkreise, welche mittels aktiven B6 und passiven B12 Gleichrichtern aus dem Dreiphasennetz gespeist werden. Eine mögliche Alternative ist die B6 Diodenbrücke in Kombination mit einem aktiven Netzfilter, welcher aufgrund der parallelen Anordnung eine höhere Leistungsdichte aufweist und darüber hinaus mehrere Geräte gleichzeitig entstören kann. Die alleinige Nutzung einer Diodenbrücke ist aufgrund des hohen Anteils von Stromharmonischen nicht zulässig. Diese Arbeit beschäftigt sich mit der Entwicklung eines aktiven Filters für ein Dreiphasensystem mit variabler Frequenz von 360 bis 800 Hz. Es werden alle relevanten Bauteile wie Induktivitäten, EMV-Filter, Leistungsmodule und Zwischenkreiskondensator ausgelegt. Besonderes Augenmerk liegt auf dem kundenspezifischen Modul mit SiC-Dioden und SiCMOSFETs, welches vollständig elektrisch und thermisch charakterisiert wird. Die Änderung der Netzfrequenz beträgt bis zu 50 Hz/ms, was eine hohe Dynamik und Robustheit von der Filterregelung verlangt. Weiterhin ist im statischen Fall eine hohe Genauigkeit gefordert, da die 5. und 7. Harmonische auf unter 2% geregelt werden müssen. Um beiden Anforderungen gerecht zu werden, wird ein zweistufiger Regelungsalgorithmus entwickelt der auf zwei digitalen Signalprozessoren implementiert wird. Simulationen und Labormessungen bestätigen die Robustheit des Regelungskonzeptes. Diese Arbeit stellt umfassend die Entwicklung von Luftfahrtgleichrichtern dar. Die Ergebnisse wurden in Konferenzen und Patenten veröffentlicht.
54

Technik und Bildung in der verwissenschaftlichten Lebenswelt

Lumila, Minna 02 June 2023 (has links)
Die Studie versucht, Husserls Modell einer nicht-wissenschaftlichen Lebenswelt für pädagogische Untersuchungen zum Verhältnis von Technik und Bildung in der verwissenschaftlichen Welt zu öffnen. Sie diskutiert Entwicklungsprobleme der Spätmoderne unter pluralen Fragestellungen und führt Ansätze und Traditionen zusammen, die unterschiedliche Wege zur Weiterentwicklung der modernen Bildungstheorie beschritten haben. Im Zentrum steht die Frage, wie moderne Technik einerseits als lebensweltliche Entfremdung des Menschen problematisiert und andererseits als Produkt menschlicher Freiheit und Weltgestaltung gewürdigt werden kann. In vier Kapiteln werden die methodischen Ansätze und Antworten vorgestellt, die der Philosoph und Pädagoge Eugen Fink (1905–1975), der Philosoph Martin Heidegger (1889–1976), der Philosoph und Erziehungswissenschaftler Theodor Litt (1880–1962) und der Soziologe Helmut Schelsky (1912–1984) auf die Frage nach dem Verhältnis von Bildung und Technik gegeben haben. Im Durchgang durch ihre Positionen wird ein Konzert erarbeitet, dessen Originalität darin liegt, Abstimmungsprobleme von Bildung, Technik und Lebenswelt aus postdualistischer, praxistheoretischer sowie posthumanistischer Perspektive zu thematisieren. / The study attempts to open Husserl's model of a non-scientific lifeworld for pedagogical investigations of the relationship between technology and “Bildung” in the scientific world. It discusses developmental problems of late modernity under plural questions and brings together approaches and traditions that have taken different paths to the further development of modern “Bildungs”-theory. The central question is how modern technology can be problematized on the one hand as the alienation of human beings from the world of life and on the other hand be appreciated as a product of human freedom and the shaping of the world. Four chapters present the methodological approaches and answers that philosopher and educator Eugen Fink (1905–1975), philosopher Martin Heidegger (1889–1976), philosopher and educationalist Theodor Litt (1880–1962), and sociologist Helmut Schelsky (1912–1984) have given to the question of the relationship between education and technology. In the course of their positions, a concert will be developed whose originality lies in addressing the coordination problems of “Bildung” (education), “Technik” (technology) and “Lebenswelt” (lifeworld) from a post-dualist, praxis-theoretical as well as post-humanist perspective.

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