Concurrent Design studies have become of great importance in the space industry reducing the time and costs associated to the feasibility assessments for future space missions. This has also helped companies and space agencies to be at the forefront of this fast-developing sector. These collaborative sessions are carried out by an interdisciplinary group of engineers, experts and customers who are capable of achieving an optimal design solution within a short period of time, typically a few weeks. They make use of dedicated tools, like COMET® which is developed by RHEA Group, to store and share the data within the team, as well as with other partners or stakeholders. As new software tools are developed for Model-Based Systems Engineering (MBSE) applications, parallel improvements are needed for Concurrent Engineering teams, since this can be one of the first steps for a model-based approach. One of the main constraints during Concurrent Design studies is the limited number of analysed options, since evaluating the entire design space would require longer sessions and increased time availability from the experts, and would consequently result in more expensive projects. One solution for this problem can be the application of generative engineering technologies to Concurrent Design studies. This method would allow to explore the entire design space by first defining the study model together with the system constraints, and then using a software to automatically generate all the possible architecture variants for that specific model. An example of state-of-the-art technologies for generative design is Simcenter™ Studio, a recently released tool from Siemens Digital Industries Software. The complexity of space missions requires a very detailed definition and evaluation of the system architecture, even at the early stages of the design process. Therefore, research is needed on the use and implementation of new methodologies that will tackle the challenges related to Concurrent Design. The context of the research presented in this thesis is the new project proposed by RHEA Group, Siemens and OHB, called Generative Concurrent Design (GCD). It aims to combine their software tools COMET® and Simcenter Studio, bringing generative engineering to Concurrent Design. One of the main advantages is achieving more optimised solutions in shorter times, reducing the number of necessary iterations on the system architecture during the entire project lifecycle. An enhanced feature of this tool is the possibility for the users to explore the solutions trade space with the support of an Artificial Intelligence (AI) based system. This thesis presents and demonstrates the application of the GCD methodology to a use case at system level, focused on the evaluation of configuration and assembly options in the design of a spacecraft. Using the mission EnVision, selected in 2021 by ESA’s Science Programme Committee, as the design baseline, the GCD methodology has been implemented in this use case study making use of both software tools and showing potential future features and applications. / Les études de conception concourante ont pris une grande importance dans l'industrie spatiale, en réduisant le temps et les coûts associés aux évaluations de faisabilité des futures missions spatiales. Cela a également permis aux entreprises et aux agences spatiales d'être à l'avant-garde de ce secteur en plein essor. Ces sessions de collaboration sont menées par un groupe interdisciplinaire d'ingénieurs, d'experts et de clients qui sont capables d'obtenir une solution de conception optimale dans un délai court, généralement quelques semaines. Ils utilisent des outils dédiés, comme COMET® qui est développé par RHEA Group, pour stocker et partager les données au sein de l'équipe, ainsi qu'avec d'autres partenaires ou parties prenantes. Au fur et à mesure que de nouveaux outils logiciels sont développés pour les applications d'ingénierie des systèmes basés sur les modèles (MBSE), des améliorations parallèles sont nécessaires pour les équipes d'ingénierie concourante, car cela peut constituer l'une des premières étapes d'une approche basée sur les modèles. L'une des principales contraintes lors des études de conception concourante est le nombre limité d'options analysées, car l'évaluation de l'ensemble de l'espace de conception nécessiterait des sessions plus longues et une plus grande disponibilité des experts, ce qui se traduirait par des projets plus coûteux.  Une solution à ce problème pourrait être l'application des technologies d'ingénierie générative aux études de conception concourante. Cette méthode permettrait d'explorer l'ensemble de l'espace de conception en définissant d'abord le modèle d'étude ainsi que les contraintes du système, puis en utilisant un logiciel pour générer automatiquement toutes les variantes possibles du système pour ce modèle spécifique. Un exemple de technologies de pointe pour la conception générative est Simcenter™ Studio, un outil récemment publié par Siemens Digital Industries Software.  La complexité des missions spatiales exige une définition et une évaluation très détaillées de l'architecture du système, même aux premiers stades du processus de conception. Par conséquent, des recherches sont nécessaires sur l'utilisation et la mise en œuvre de nouvelles méthodologies qui permettront de relever les défis liés à la conception concourante. Le contexte de la recherche présentée dans cette thèse est le nouveau projet proposé par RHEA Group, Siemens et OHB, appelé Conception Concurrente Générative (Generative Concurrent Design ou GCD en anglais). Il vise à combiner leurs outils logiciels COMET® et Simcenter Studio, en apportant l'ingénierie générative à la conception concourante. L'un des principaux avantages est de parvenir à des solutions plus optimisées dans des délais plus courts, en réduisant le nombre d'itérations nécessaires sur l'architecture du système pendant tout le cycle de vie du projet. Une caractéristique améliorée de cet outil est la possibilité, pour les utilisateurs, d'explorer l'espace commercial des solutions avec le soutien d'un système basé sur l'intelligence artificielle (IA). Cette thèse présente et démontre l'application de la méthodologie GCD à un cas d'utilisation au niveau système, centré sur l'évaluation des options de configuration et d'assemblage dans la conception d'un vaisseau spatial. En utilisant la mission EnVision, sélectionnée en 2021 par le Comité du Programme Scientifique de l'ESA, comme base de conception, la méthodologie GCD a été mise en œuvre dans cette étude de cas d'utilisation, en employant les deux outils logiciels et en montrant les fonctionnalités et applications potentielles futures.

In the course of revitalizing the Poseidon Building in Frankfurt, an energetically optimized façade, made of an architectural concrete was developed. The development of a fiber-reinforced architectural concrete had to consider the necessary mechanical strength, design technology and surface quality. The fiber-reinforced architectural concrete has a compressive strength of 104.1 MPa and a 3-point bending tensile strength of 19.5 MPa. Beyond that, it was ensured that the fiber-reinforced high-performance concrete had a high durability, which has been shown by the capillary suction of de-icing solution and freeze thaw test with a weathering of abrasion of 113 g/m² after 28 freeze-thaw cycles and a mean water penetration depth of 11 mm.

In the course of revitalizing the Poseidon Building in Frankfurt, an energetically optimized façade, made of architectural concrete was developed. The development of a fiber-reinforced architectural concrete had to consider the necessary mechanical strength, design technology and surface quality. The fiber-reinforced architectural concrete has a compressive strength of 104.1 MPa and a 3-point bending tensile strength of 19.5 MPa. Beyond that, it was ensured that the fiber-reinforced high-performance concrete had a high durability, which has been shown by the capillary suction of de-icing solution and freeze thaw test with a weathering of abrasion of 113 g/m² after 28 freeze-thaw cycles and a mean water penetration depth of 11 mm.

We address two computational challenges for numerical simulations of Darcy flow problems: rough and uncertain data. The rapidly varying and possibly high contrast permeability coefficient for the pressure equation in Darcy flow problems generally leads to irregular solutions, which in turn make standard solution techniques perform poorly. We study methods for numerical homogenization based on localized computations. Regarding the challenge of uncertain data, we consider the problem of forward propagation of uncertainty through a numerical model. More specifically, we consider methods for estimating the failure probability, or a point estimate of the cumulative distribution function (cdf) of a scalar output from the model. The issue of rough coefficients is discussed in Papers I–III by analyzing three aspects of the localized orthogonal decomposition (LOD) method. In Paper I, we define an interpolation operator that makes the localization error independent of the contrast of the coefficient. The conditions for its applicability are studied. In Paper II, we consider time-dependent coefficients and derive computable error indicators that are used to adaptively update the multiscale space. In Paper III, we derive a priori error bounds for the LOD method based on the Raviart–Thomas finite element. The topic of uncertain data is discussed in Papers IV–VI. The main contribution is the selective refinement algorithm, proposed in Paper IV for estimating quantiles, and further developed in Paper V for point evaluation of the cdf. Selective refinement makes use of a hierarchy of numerical approximations of the model and exploits computable error bounds for the random model output to reduce the cost complexity. It is applied in combination with Monte Carlo and multilevel Monte Carlo methods to reduce the overall cost. In Paper VI we quantify the gains from applying selective refinement to a two-phase Darcy flow problem.

In the course of revitalizing the Poseidon Building in Frankfurt, an energetically optimized façade, made of an architectural concrete was developed. The development of a fiber-reinforced architectural concrete had to consider the necessary mechanical strength, design technology and surface quality. The fiber-reinforced architectural concrete has a compressive strength of 104.1 MPa and a 3-point bending tensile strength of 19.5 MPa. Beyond that, it was ensured that the fiber-reinforced high-performance concrete had a high durability, which has been shown by the capillary suction of de-icing solution and freeze thaw test with a weathering of abrasion of 113 g/m² after 28 freeze-thaw cycles and a mean water penetration depth of 11 mm.

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ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / Over the past several years DoD imposed constraints on test deliverables, requiring objective measures of test results, i.e., statistically defensible test and evaluation (SDT&E) methods and results. These constraints force the tester to employ statistical hypotheses, analyses and perhaps modeling to assess test results objectively, i.e., based on statistical metrics, probability of confidence and logical inference to supplement rather than rely solely on expertise, which is too subjective. Experts often disagree on interpretation. Numbers, although interpretable, are less variable than opinion. Logic, statistical inference and belief are the bases of testable, repeatable and refutable hypothesis and analyses. In this paper we apply linear regression modeling and analysis of variance (ANOVA) to time-space position information (TSPI) to determine if a telemetry (TM) antenna control unit (ACU) under test (AUT) tracks statistically, thus as efficiently, in C-band while receiving both C- and S-band signals. Together, regression and ANOVA compose a method known as analysis of covariance (ANCOVA). In this, the second of three papers, we use data from a range test, but make no reference to the systems under test, nor to causes of error. The intent is to present examples of tools and techniques useful for SDT&E methodologies in testing.

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In the course of revitalizing the Poseidon Building in Frankfurt, an energetically optimized façade, made of architectural concrete was developed. The development of a fiber-reinforced architectural concrete had to consider the necessary mechanical strength, design technology and surface quality. The fiber-reinforced architectural concrete has a compressive strength of 104.1 MPa and a 3-point bending tensile strength of 19.5 MPa. Beyond that, it was ensured that the fiber-reinforced high-performance concrete had a high durability, which has been shown by the capillary suction of de-icing solution and freeze thaw test with a weathering of abrasion of 113 g/m² after 28 freeze-thaw cycles and a mean water penetration depth of 11 mm.

RCs (Reverberation Chambers) has historically been used mainly for aerospace and military purposes in EMC (Electromagnetic Compatibility) testing, but the interest also seems to increase in the automotive industry (the development of an international standard for vehicles is in progress). The vehicles of the future will most likely be electrified, wirelessly connected and autonomous, i.e., more control units, more communication systems, and more sensors, will be implemented in the vehicles requiring increased robustness against all possible electromagnetic interferences. EMC testing in an RC is a step in the direction of ensuring this robustness for the future vehicle platforms. Compared to a traditional EMC test method in a fully or semi-AC (Anechoic Chamber), testing in an RC has the advantage that the electromagnetic field will be isotropic, randomly polarized and homogeneous in a statistical sense, i.e., the exposed object will be surrounded by electromagnetic energy from all directions. It can be considered relatively expensive to build a brand new RC with motorized stirrers and associated measurement instrumentation, instead it would be desirable to perform immunity tests in a more cost-effective conductive fabric tent. The great advantage is the flexibility, the tent can be set up almost anywhere, even in already existing semi-ACs, such set-up is referred to as VIRC (Vibrating Intrinsic Reverberation Chamber). This thesis aims to develop a new test method in a VIRC environment. In order to achieve good RC conditions, the electromagnetic field must be statistically Rayleigh distributed. Furthermore, it is of great importance to avoid LoS (Line of Sight) between the antenna and the test object, and to achieve good stirring in the tent. Provided this can be achieved, there are still some challenges by testing in a tent. For example, the classical dwell time of two seconds for immunity testing in EMC is not possible to achieve in a VIRC environment. The validation in this thesis shows that the dwell time or the total exposure time in the tent might be enough to trigger possible malfunctions in today's modern high-speed communication vehicles. Furthermore, it is showed, testing in a VIRC gives good field uniformity and repeatability, and can trigger malfunctions that are not triggered in traditional EMC testing in semi-AC, i.e., ALSE (Absorber-Lined Shielded Enclosure) testing.