Thesis (Ph. D.)--Göteborgs universitet, 1995. / Includes bibliographical references (p. [243]-257) and index.

Thesis (Ph. D.)--Göteborgs universitet, 1995. / Includes bibliographical references (p. [243]-257) and index.

1 Abstract The thesis tries to evaluate the contribution of Didymus of Alexandria in the field of pneumatology and situate it in the context of theology of his contemporaries and the Alexandrian tradition. Pneumatology is one of the main themes of Didymus, but the only existing treatise, which is directly dedicated to this theme and we are sure of his authorship, is On the Holy Spirit, This treatise, possibly the historicaly first of its kind, thus represents the the focus of this thesis. It has been preserved only in Latin translation of Jerome which renders the Greek text and Didymus' original teachings complicated to fully recover. The first part of the thesis is dedicated to Didymus life and work. It presents his formation, studies, methods of teaching in the framework of Alexandrian catechetist school, theological and exegetical activities, his ascetic attitude to life, and his condemnation after his death in the framework of anti-origenist struggle. Then the Didymus writings are then devided into dogmatic and exegetical works, the latter of which was enriched by the finds of codexes in Egyptian Tura in 1941. The discovered works became new impulse to the study Didymus' teachings and methods. The second part of the thesis then deals with triadological disputes during the 4th century, with a stress on...

Many space probes have conducted in situ explorations of asteroids, in recent decades, intent on identifying evidence of the solar system's earliest processes of formation within the asteroids' interiors. Several future asteroid missions are planned, among which include ESA's Hera mission to explore the Didymos binary asteroid pair. An ion mass analyzer is currently being designed at the Swedish Institute of Space Physics for use as part of the Hera mission. This thesis aims to optimize the instrument such that each of its parameters meets the requirement for performance. A computer simulation is used to calculate the trajectories of low-energy ions inside the instrument, where the electrostatic potential are imposed by grids and electrodes embedded inside the instrument. From the data analysis of the simulation results, the performance for each parameter can be derived. By changing the settings of the grids and electrodes (e.g., positions and voltages), the instrument parameters are to be optimized. Two tasks are set up in this project--- the first task is to optimize the focusing system of the incoming ions at the instrument's entrance, and the second task is to investigate the reflectron system so that the mass resolution of the instrument can be optimized via reducing the spread of the ions' time of flight spectra. The focusing system is found to already be optimized, but instead, a relation between its position of the grid at the instrument's entrance and the instrument's performance is derived. The method of and parameters for optimization within the reflectron are extensively tested individually during this project. Although several performances in each trial from the reflectron analysis cannot meet at least one of the requirements, enough scenarios are examined such that every parameter tested ends with a value suitable to be applied individually to optimize the ion mass analyzer. The findings from the individual tests done in this project can be applied to further optimization, particularly to optimize multiple parameters simultaneously in the near future.

The Gospel According to Thomas is found in the second manuscript of codex II of a set of texts found in Nag Hammadi, Egypt, collectively referred to today as the Coptic Gnostic Library. This gospel was readily identified as Thomas due to fragments of a Greek version of the text having already been discovered and identified in the 1890s at Oxyrhynchus, Egypt. However, the discovery near Nag Hammadi in 1945 C.E. was not of fragments, but it actually contained the entire text of Thomas. Thus, the finding of the entire text in Nag Hammadi brought about a set of questions that had not yet surfaced from the fragments of Thomas previously found at Oxyrhynchus, Egypt. For example, was Thomas actually written by Didymus Jude Thomas? If Thomas did not write it, then by whom was it written, and why did the actual author claim it to be written by Thomas?

The Gospel According to Thomas is found in the second manuscript of codex II of a set of texts found in Nag Hammadi, Egypt, collectively referred to today as the Coptic Gnostic Library. This gospel was readily identified as Thomas due to fragments of a Greek version of the text having already been discovered and identified in the 1890s at Oxyrhynchus, Egypt. However, the discovery near Nag Hammadi in 1945 C.E. was not of fragments, but it actually contained the entire text of Thomas. Thus, the finding of the entire text in Nag Hammadi brought about a set of questions that had not yet surfaced from the fragments of Thomas previously found at Oxyrhynchus, Egypt. For example, was Thomas actually written by Didymus Jude Thomas? If Thomas did not write it, then by whom was it written, and why did the actual author claim it to be written by Thomas?

This thesis describes the design, implementation and analysis for a preliminary study for DLR's MASCOT lander's next mission to Small Solar System Bodies (SSSB). MASCOT (Mobile Asteroid Surface Scout) is a nano-lander that flew aboard Hayabusa2 (JAXA) to an asteroid, Ryugu. It is a passive nano-spacecraft that can only be deployed ballistically from a hovering spacecraft. Current research focusses on optimizing similar close-approach missions for deploying landers or small cubesats into periodic orbits but does not provide solutions with semi-autonomous small landers deployed from farther distances. This study aims to overcome this short-coming by proposing novel yet simple Guidance, Navigation and Control (GNC) and Propulsion systems for MASCOT. Due to its independent functioning and customisable anatomy, MASCOT can be adapted for several mission scenarios. In this thesis, a particular case-study is modelled for the HERA (ESA) mission. The first phase of the study involves the design of a landing trajectory to the moon of the Didymos binary asteroid system. For a preliminary analysis, the system - Didymain (primary body), Didymoon (secondary body) and MASCOT (third body) - are modelled as a Planar Circular Restricted Three Body Problem (PCR3BP). The numerical integration methodology used for the trajectory is the variable-step Dormand–Prince (Runge Kutta) ODE-4,5 (Ordinary Differential Equation) solver. The model is built in MATLAB-Simulink (2019a) and refined iteratively by conducting a Monte Carlo analysis using the Sensitivity Analysis Tool. Two models - a thruster-controlled system and an alternative hybrid propulsion system of solar sails and thrusters - are simulated and proven to be feasible. The results show that the stable manifold near Lagrange 2 points proposed by Tardivel et. al. for ballistic landings can still be exploited for distant deployments if a single impulse retro-burn is done at an altitude of 65 m to 210 m above ground with error margins of 50 m in position, 5 cm/s in velocity and 0.1 rad in attitude. The next phase is the conceptual design of a MASCOT-variant with GNC abilities. Based on the constraints and requirements of the flown spacecraft, novel GNC and Propulsion systems are chosen. To identify the overriding factors in using commercial-off-the-shelf (COTS) for MASCOT, a market survey is conducted and the manufacturers of short-listed products are consulted. The final phase of the study is to analyse the proposed equipment in terms of parameter scope and capability-oriented trade-offs. Two traceability matrices, one for devised solutions and system and another for solutions versus capabilities, are constructed. The final proposed system is coherent with the given mass, volume and power constraints. A distant deployment of MASCOT-like landers for in-situ observation is suggested as an advantageous and risk-reducing addition to large spacecraft missions to unknown micro-gravity target bodies. Lastly, the implications of this study and the unique advantages of an enhanced MASCOT lander are explored for currently planned SSSB missions ranging from multiple rendezvous, fly-by or sample-return missions. Concluding, this study lays the foundation for future work on advanced GNC concepts for unconventional spacecraft topology for the highly integrated small landers. / <p>This thesis is submitted as per the requirements for the Spacemaster (Round 13) dual master's degree under the Erasmus Mundus Joint Master's Degree Programme. </p> / MASCOT team, DLR