Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 380-396). Also available on the Internet.

This thesis presents a newly developed manufacturing method, based on cyber-physically enhanced hybrid machining, regarding an optical bench (OB) made of Ti6Al4V alloy for the Advanced Telescope for High-ENergy Astrophysics (ATHENA). The method includes sophisticated hybrid laser metal deposition equipment and state-of-the-art cryogenic machining hardware. The derived strategy combines localized energy input, preheating, heat treatment, intermediate stress relief and machining. This results in a complex thermal history and remaining residual stresses, representing a considerable challenge for final precision machining. The method targets first time right machining based on iterative machining, process data-based tool path correction and spatially resolved root cause research based on process data modeling.:II. Table of Contents I. Acknowledgement ............................................................ III II. Table of Contents ................................................................. I 1. Introduction ........................................................................ 1 1.1 Foreword .................................................................................... 1 1.2 Research Subject Lot Size One ....................................................... 2 1.2.1 Historical Perspective ................................................................. 2 1.2.2 Going Full Cycle ......................................................................... 3 2. State of the Art in Titanium Processing ............................... 4 2.1 Conventional Processing................................................................ 4 2.2 Additive Manufacturing ................................................................. 5 2.2.1 Introduction .............................................................................. 5 2.2.2 Powder Bed Fusion ..................................................................... 6 2.2.3 Direct Energy Deposition ............................................................. 8 3. Derivation of a Flexible Hybrid Manufacturing System ...... 11 3.1 The ATHENA OB – a Large Structural Space Component ..................11 3.2 Material Constraints ....................................................................12 3.3 Solidification and Microstructural Content .......................................17 3.4 Residual Stresses and Intrinsic Heat Treatment ..............................22 3.4.1 Transient Temperature Gradients ................................................22 3.4.2 Residual Stresses and Degree of Fixity ........................................24 3.4.3 In-situ Stress Relief and Plastic Deformation ................................28 3.4.4 In-situ Martensite Decomposition and Thermal Trade-off ...............30 3.5 Melt Pool Considerations in Laser Metal Deposition ..........................36 3.6 Concept of Flexible Hybrid Manufacturing Cell .................................43 3.7 Process and Equipment Review by ESA ..........................................45 4. Realization of a Flexible Manufacturing Cell ...................... 45 4.1 Additive Processing with Hybrid Laser Metal Deposition ....................45 4.1.1 Principle Hardware ....................................................................45 4.2 Novel Local Shielding Solution ......................................................47 4.2.1 Melt Pool Observation towards Process Data Model ........................51 4.2.2 Energy Source Coupling .............................................................57 4.3 Subtractive Processing with Cryogenic Milling .................................57 4.3.1 General Considerations for Subtractive Processing ........................57 4.3.2 Cryogenic Machining Approach ...................................................58 4.3.3 Cryogenic Machining from the Materials Viewpoint ........................60 4.3.4 Cryogenic Machining of Additively Manufactured Ti-6Al-4V .............62 4.3.5 Principle Hardware for Cryogenic Milling with CO2..........................66 4.3.6 Intelligent Tool Spindle Future Part of the Process Data Model ........69 4.3.7 Carbon Dioxide Weighing Equipment and Switching Station ............70 4.3.8 Protective Measures for Safe Use of Cryogenic CO2 .......................72 4.4 Handling System .........................................................................74 4.4.1 Framework Considerations .........................................................74 4.4.2 Twin Robot System in the Initial State .........................................76 4.4.3 Integration of the ATHENA Turntable ...........................................79 4.4.4 Robot Calibration ......................................................................81 4.5 Lighting for Visual Inspection ........................................................84 4.6 Critical Design Review by ESA .......................................................84 5. Implementation and Validation ......................................... 85 5.1 Powdery Filler Material Selection ...................................................85 5.2 Basic Parameter Set for Additive Manufacturing ..............................87 5.2.1 Operating Point Selection ...........................................................87 5.2.2 Characterization and evaluation ..................................................89 5.2.3 Substrate to Structure Transition ................................................95 5.3 Energy Source Coupling ...............................................................99 5.3.1 Process Development ................................................................99 5.3.2 As-built Surface Treatment ...................................................... 103 5.3.3 Heat Treatment ...................................................................... 104 5.3.4 Mechanical Testing .................................................................. 106 5.3.5 Fractured Surfaces .................................................................. 108 5.3.6 Microstructure ........................................................................ 110 5.3.7 Linear Expansion Coefficient ..................................................... 113 5.4 Cryogenic Milling ....................................................................... 114 5.4.1 Strategy Approach .................................................................. 114 5.4.2 Milling Implementation ............................................................ 116 5.4.3 Technical Cleanliness ............................................................... 120 5.4.4 Accuracy and Duration ............................................................. 122 5.4.5 Surface Roughness.................................................................. 122 5.5 Process Data Model ................................................................... 123 6. Final Discussion and Conclusions..................................... 130 6.1 Summary ................................................................................. 130 6.2 Conclusions .............................................................................. 131 6.3 Outlook .................................................................................... 132 III. List of Figures ...................................................................... I IV. List of Tables .................................................................. VIII V. References ......................................................................... IX VI. Symbols and Units ....................................................... XXXVI VII. Abbreviations .............................................................. XXXIX VIII. Annex I ............................................................................ XLI IX. Annex II ....................................................................... XLIII X. Annex III ....................................................................... XLIV XI. Annex IV.......................................................................... XLV XII. Annex V ......................................................................... XLVI XIII. Annex VI....................................................................... XLVII XIV. Annex VII ................................................................... XLVIII

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.

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.

The objective of this thesis is to examine how the bereavement of a mother tongue in various ways affects a person and how literature discusses this experience. How does literature reflect it and is it possible to identify any specific and recurring themes? Are there any similarities between the experience of migration and the experience of colonialism? What purpose does writing serve in this and how to describe the impact of language? Hopefully this thesis will contribute to a better understanding of the situation for newly arrived people and for persons living in Sweden with Swedish as a second language. The thesis has a postcolonial perspective as the focus is fiction dealing with a relocation from east to west. Earlier research and writings that has inspired is in particular the works by the two postcolonial theorists Franz Fanon and Sara Ahmed. The main source material for the study is literary works, e.g. the works of Jila Mossaed, Theodor Kallifatides, Athena Farrokhzad, Burcu Sahin and Yoko Tawada. The thesis is intentionally written in the form of an essay, suggesting the power of language and storytelling. The main objective of the thesis is to describe, rather than to arrive at a conclusion. One main focus is the author’s personal relation to the subject and to the Philippines and its colonial past. The literary works addressed in this study suggests that literature dealing with migration and language bereavement mainly focuses on a discussion about the relation between the native tongue and the new language, the relation between the metaphysical body and the new geographical location, about feelings of speechlessness and alienation that becomes physical. All these concurrent themes can be used as tools to define an experience that in many aspects is inconceivable. The thesis also identifies similarities between colonialism and migration, as both raise the question of inherit right to a place and a lifelong search for a place to call home. In this effort, writing is important and may function as an emancipatory lever to create new places.

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Quoi de plus inné que les concepts d’oblique, d’horizontal ou de vertical ? Pour nous, moderne, ces concepts fondamentaux sont la base de tout notre système de pensée, tant mathématique qu’artistique. Tout porterait à croire que ces principes soient présents dans la civilisation grecque, dont nous nous réclamons les héritiers. Ce n’est pourtant pas une évidence au vu des textes qui nous ont été rapportés. Homère n’a pas connu le concept d’oblique – aucun mot ne saurait le traduire dans la langue de son époque. Et même plus tard. Les Grecs ont cinq adjectifs pour signifier approximativement l’oblique : λοξός, πλάγιος, λέχριος, σκολιός et δόχμιος. Chaque discipline (cosmologie, optique, géographie, artistique, etc.) a sa façon d’appréhender ces cinq termes, qui ne recouvrent à chaque fois que partiellement notre notion d’oblique. Paradoxalement, ce que le langage écrit n’a pas synthétisé se retrouve en abondance dans l’imagerie. Plus surprenant encore, l’oblique dans l’image, que nous considérons comme signe du mouvement dans notre langage iconographique, se retrouve aussi bien pour signifier le mouvement que le repos. Deux monuments de l’art grec attirent notre attention sur ce nouveau paradoxe : la frise du Mausolée d’Halicarnasse et l’Athéna Pensive. A chaque fois l’oblique est présente, à chaque fois elle porte deux sens bien distincts. Ces deux formes de langage, écrit et imagé, apportent un éclairage différent, et pour le moins complémentaire, sur la façon dont les Grecs de l’Antiquité ont appréhendé (ou non) le concept d’oblique. / What could be more innate than the concepts of oblique, horizontal or vertical ? For us, modern, these three concepts are the basis of our whole system of thought, both mathematical and artistic. It would appear to be obvious that these principles are present in the Greek civilization, whose we claim the heirs. However that isn't so obvious in view of the texts that have survived. Homer didn’t know the concept of oblique - no words can translate it into the language of his time. And even later. The Greeks have five adjectives to mean approximately oblique : λοξός, πλάγιος, λέχριος, σκολιός and δόχμιος. Each discipline (cosmology, optic, geography, art, etc.) has its own way of looking at these five words, which cover partially our notion of oblique. Paradoxically, what the written language has not synthesized, can be found in many images. Even more surprising, the oblique in the image, which we consider as a sign of movement in our iconographic language, is found both here to signify the movement than the rest. Two monuments of Greek art call our attention to this new paradox : the frieze of the Mausoleum of Halicarnassus and the Mourning Athena. In each of them the oblique ligne is present, and wears two distinct senses. These two forms of language, written and pictorial, bring a different perspective, furthermore complementary, on how the ancient Greeks apprehended (or not) the concept of oblique.

Cette thèse est consacrée au développement d'un modèle End-to-End pour le spectrocalorimètre X-IFU qui observera à partir de 2028 l'Univers en rayons X avec une précision jamais atteinte auparavant. Ce travail s'est essentiellement organisé en deux parties. J'ai dans un premier temps étudié la dynamique des parties les plus internes des binaires X de faible masse à l'aide de deux sondes particulières que sont les sursauts X et les oscillations quasi-périodiques au kHz (kHz QPOs). En me basant sur les données d'archive du satellite Rossi X-ray Timing Explorer et sur des méthodes d'analyse spécifiquement développées dans ce but, j'ai notamment pu mettre en évidence pour la première fois une réaction du premier sur le second, confirmant le lien très étroit entre ces oscillations et les parties les plus internes du système. Le temps de rétablissement du système suite aux sursauts entre également en conflit dans la plupart des cas avec l'augmentation supposée du taux d'accrétion suite à ces explosions. Au travers d'une analyse spectro-temporelle complète des deux kHz QPOs de 4U 1728-34, j'ai également pu confirmer l'incompatibilité des spectres de retard des deux QPOs qui suggère une origine différente de ces deux oscillations. L'étude de leurs spectres de covariance, obtenus pour la première fois dans cette thèse, a quant à elle mis en évidence le rôle central de la couche de Comptonisation et potentiellement celui d'une zone particulièrement compacte de la couche limite pour l'émission des QPOs. Dans le second volet de ma thèse, j'ai développé un simulateur End-to-End pour l'instrument X-IFU permettant de représenter l'ensemble du processus menant à une observation scientifique en rayons X, de l'émission des photons par une source jusqu'à leur mesure finale à bord du satellite. J'ai notamment mis en place des outils permettant la comparaison précise de plusieurs matrices de détecteurs en prenant en compte les effets de la reconstruction du signal brut issu des électroniques de lecture. Cette étude a mis en évidence l'intérêt de configurations hybrides, contenant une sous-matrice de petits pixels capables d'améliorer par un ordre de grandeur la capacité de comptage de l'instrument. Une solution alternative consisterait à défocaliser le miroir lors de l'observation de sources ponctuelles brillantes. Situées au coeur de la performance du X-IFU, j'ai également comparé de manière exhaustive différentes méthodes de reconstruction des signaux bruts issus des détecteurs X-IFU. Ceci a permis de montrer qu'à faible coût en termes de puissance de calcul embarquée, une amélioration significative de la résolution en énergie finale de l'instrument pouvait être obtenue à l'aide d'algorithmes plus sophistiqués. En tenant compte des contraintes de calibration, le candidat le plus prometteur apparaît aujourd'hui être l'analyse dans l'espace de résistance. En me servant de la caractérisation des performances des différents types de pixels, j'ai également mis en place une méthode de simulation rapide et modulable de l'ensemble de l'instrument permettant d'obtenir des observations synthétiques à long temps d'exposition de sources X très complexes, représentatives des futures capacités du X-IFU. Cet outil m'a notamment permis d'étudier la sensibilité de cet instrument aux effets de temps mort et de confusion, mais également d'estimer sa future capacité à distinguer différents régimes de turbulence dans les amas de galaxies et de mesurer leur profil d'abondance et de température. A plus long terme ce simulateur pourra servir à l'étude d'autres cas scientifiques, ainsi qu'à l'analyse d'effets à l'échelle de l'ensemble du plan de détection tels que la diaphonie entre pixels. / This thesis is dedicated to the development of an End-ta-End model for the X-IFU spectrocalorimeter scheduled for launch in 2028 on board the Athena mission and which will observe the X-ray universe with unprecedented precision. This work has been mainly organized in two parts. I studied first the dynamics of the innermost parts of low mass X-ray binaries using two specific probes of the accretion flow: type I X-ray bursts and kHz quasi-periodic oscillations (kHz QPOs). Starting from the archivai data of the Rossi X-ray Timing Explorer mission and using specific data analysis techniques, I notably highlighted for the first time a reaction of the latter to the former, confirming the tight link between this oscillation and the inner parts of the system. The measured recovery time was also found in conflict with recent claims of an enhancement of the accretion rate following these thermonuclear explosions. From the exhaustive spectral timing analysis of both kHz QPOs in 4U 1728-34, I further confirmed the inconsistancy of their lag energy spectra, pointing towards a different origin for these two oscillations. The study of their covariance spectra, obtained here for the first time, has revealed the key role of the Comptonization layer, and potentially of a more compact part of it, in the emission of the QPOs. In the second part of my thesis, I focused on the development of an End-to-:End simulator for the X-IFU capable of depicting the full process leading to an X-ray observation, from the photon emission by the astrophysical source to their on-board detection. I notably implemented tools allowing the precise comparison of different potential pixel array configurations taking into account the effects of the event reconstruction from the raw data coming from the readout electronics. This study highlighted the advantage of using hybrid arrays containing a small pixel sub-array capable of improving by an order of magnitude the count rate capability of the instrument. An alternative solution would consist in defocusing the mirror during the observation of bright point sources. Being a key component of the overall X-IFU performance, I also thoroughly compared different reconstruction methods of the pixel raw signal. This showed that with a minimal impact on the required on-board processing power, a significant improvement of the final energy resolution could be obtained from more sophisticated reconstruction methods. Taking into account the calibration constraints, the most promising candidate currently appears to be the so-called "resistance space analysis". Taking advantage of the obtained performance characterization of the different foreseen pixel types, I also developed a fast and modular simulation method of the complete instrument providing representative synthetic observations with long exposure times of complex astrophysical sources suffinguish different turbulence regimes in galaxy clusters and to measure abundance and temperature profiles. In the longer run, this simulator will be useful for the study of other scientific cases as well as the analysis of instrumental effects at the full detection plane level such as pixel crosstalk.

The Master's thesis focuses on loading patterns of nuclear reactors VVER. It describes the whole process of fuel cycle, since production to storage or reprocessing. The author puts emphasise on the middle part of fuel cycle in Czech nuclear power plants - Dukovany and Temelín and he also explains which fuels are used in both power plants now and which were used in history. The thesis also contains a basic overview of approaches to loading patterns optimisation in foreign countries. The final part of the thesis discusses practical calculation of loading patterns in the Block III of Nuclear power plant Dukovany, by using optimisation programme Athena and Moby-Dick macrocode.