Uppsatsen tar sin utgångspunkt i antagandet att det svenska luftvärnet under 2000- talet har haft en begränsad utveckling och att truppslaget inte har följt den internationella trenden med mer högpresterande system. Syftet med uppsatsen är att försöka förklara vad som har drivit det svenska luftvärnets utveckling och vilka faktorer som lett till att luftvärnet idag ser ut som det gör. Graham Allison klassiska verk Essence of Decision har utgjort den teoretiska referensramen som legat till grund för undersökningen. Luftvärnets utveckling har studerats utifrån perspektiven om Rationellt beslutsfattande och Maktutövat beslutsfattande. Resultatet av undersökningen visar att Allisons teorier är gynnsamma för att studera drivkrafter och förklara luftvärnets utveckling. Det maktutövade beslutsfattandet kan till stor del klargöra utvecklingen men har visat sig sakna fullständig förklaringskraft. Perspektivet kan därför med fördel nyttjas för att ge en alternativ bild av utvecklingen men inte ensamt förklara drivkrafterna bakom. Det rationella beslutsfattandet är det som av denna uppsats deklareras ha bäst förklaringskraft. Försvarsmaktens begränsade förmåga att driva utvecklingen av luftvärnet framåt antas ha berott på förändrade målsättningar som skett till följd av skiftande fokus på nationella och internationella insatser. Tilldelning av resurser har stundtals varit knapphändig men har i stora drag följt de övergripande målsättningar Försvarsmakten haft med luftvärnet. / The thesis is based on the assumption that the Swedish Ground Based Air Defense (GBAD) in the 21st century has had a limited development and has not followed the international trend of higher performance systems. The purpose of this thesis is to explain what has propelled the GBAD development and to study the underlying factors that have shaped today´s GBAD. Graham Allison classical work Essence of Decision has provided the theoretical framework that formed the basis for the study. The development of GBAD has been studied from the perspective of Rational Actor model and the Governmental Politics model. The result of the survey shows that Allison's theories are favorable for studying the driving forces and explain GBAD development. The Governmental Politics model almost provides a sufficient explanation but does not provide a comprehensive explanation. The perspective can be beneficially used to give an alternative approach of the development but not alone explain the underlying factors. The Rational Actor model offers the best explanatory power. The Swedish Armed Forces' limited ability to develop GBAD is assumed to have been a result of the changing objectives, which occurred due to an altering focus of national and international missions. Allocation of resources has, at times, been inadequate but has broadly followed the overall objectives the Armed Forces had had with GBAD.

<div>As the number of Resident Space Objects around Earth continues to increase, the need for an optimal sensor tasking strategy, specifically with Ground-Based Optical sensors, continues to be of great importance. This thesis focuses on the single and multi-sensor tasking problem with realistic optical sensor modeling for the observation of objects in the Geosynchronous Earth Orbit regime. In this work, sensor tasking refers to assigning the specific?c observation times and viewing directions of a single or multi sensor framework to either survey for or track new or existing objects. For this work specifically, the sensor tasking problem will seek to maximize the total number of Geosynchronous Earth Orbiting objects to be observed from a catalog of existing objects with a single and multi optical sensor tasking framework. This research focuses on the physical assumptions and limitations on an optical sensor, and how these assumptions affect the single and multi sensor tasking scenario. First, the concept of the probability of detection of a resident space object is calculated based on the viewing geometry of the resident space object. Then, this probability of detection is compared to the system that avoids the computational process by implementing a classical heuristic minimum elevation constraint to an electro-optical charged coupled optical sensor. It is shown that in the single and multi-sensor tasking scenario if the probability of detection is not considered in the sensor tasking framework, then a rigid elevation constraint of around 25^o-35^o is recommended for tasking Geosynchronous objects. Secondly, the topic of complete geo-coverage within a single night is explored. A sensor network proposed by Ackermann et al. (2018) is studied with and without the probability of detection considerations, and with and without uncertainties in the resident space objects' states. (then what you have). For the multi-sensor system, it is shown that with the assumed covariance model for this work, the framework developed by Ackermann et al. (2018) does not meet the design requirements for the cataloged Geosynchronous objects from March 19th, 2019. Finally, the concept of a variable repositioning time for the slewing of the ground-based sensors is introduced and compared to a constant repositioning time model. A model for the variable repositioning time is derived from data retrieved from the Purdue Optical Ground Station. This model is applied to a single sensor scenario. Optimizers are developed using the two repositioning time functions derived in this work. It is shown that the constant repositioning models that are greater than the maximum repositioning time produce results close to the variable repositioning solution. When the optimizers are tested, it is shown that there is a small increase in performance only when the maximum repositioning time is significant.</div>

The new generation of giant ground-based telescopes will see their first light this decade. These state-of-the-art facilities will significantly surpass the resolving power of modern space-based observatories such as the James Webb telescope, thanks to their enormous aperture size and adaptive optics (AO) facilities. Without AO, atmospheric turbulence would degrade the image quality of these enormous telescopes to that of a 50 cm amateur one. These extremely large telescopes (ELTs) will further benefit from a particular branch of AO called multi-conjugate adaptive optics (MCAO), which provides an extremely high resolving power over a much wider field of view as compared to classical AO systems. The design and fabrication of such systems, as well as their optimal use for science operation, pose a great challenge as they are an order of magnitude more complicated than current AO systems. To face such a challenge, the combined knowledge of MCAO system design and fabrication, working in tandem with scientific insights into new astronomy science cases, is an extremely valuable and essential pairing. This thesis is an effort to not only contribute to the design and fabrication of ELT MCAO facilities, but also provide guidance on the optimal method to utilize these giant telescopes to achieve unprecedented astrometric measurements. On the instrumentation side, in partnership with the National Research Council of Canada's - Herzberg Astronomy and Astrophysics Institute as well as W.M. Keck Observatory in Hawaii, I was involved in the design and fabrication of a cutting edge new wavefront sensor, which is the eye of an AO system. I performed opto-mechanical design and verification studies for components of the Keck infrared pyramid wavefront sensor (IR-PWFS) as well as the Keck Planet Imager and characterizer (KPIC) instrument, which have both been commissioned and are in science operation. Furthermore, I designed the alignment plan and participated in the modification and alignment operation of a few components on the Keck II adaptive optics bench on the summit of Mauna Kea. To pave the way for the design verification of future MCAO systems for ELTs, I proposed a new method for an old challenge in the path of AO system design and verification: a flexible method for precise intensity pattern injection into laboratory AO benches. AO benches are the backbone of instrument design and modeling. One of the challenges especially important for the future generation of MCAO systems for ELTs is the verification of the effect of shadowed regions on the primary mirror. During my PhD, I successfully demonstrated the feasibility of a new proposed method to accurately model the telescope pupil. This work was done in partnership with the Laboratoire d'Astrophysique de Marseille (LAM) in France. The method I developed at LAM will be implemented in the AO Lab at NRC Herzberg Astronomy and Astrophysics. As an observational astronomer, I focused on developing methods for making optimal astrometric measurements with MCAO-enabled telescopes. The expected unparalleled astrometric precision of ELTs comes with many unprecedented challenges that if left unresolved, would jeopardize the success of these facilities as they would not be able to reach their science goals. I used observations with the only available MCAO system in science operation, the Gemini MCAO system on the 8-meter Gemini South telescope in Chile, to develop and verify a pipeline specifically designed for very high-precision astrometric studies with MCAO-fed imagers. I successfully used the pipeline to provide the precise on-sky differential distortion of the Gemini South telescope and its MCAO facilities by looking deep into the core of globular cluster NGC~6723. Using this pipeline, I produced high quality proper motions with an uncertainty floor of $\sim 45$\,$\mu$as~yr$^{-1}$ as well as measured the proper motion dispersion profile of NGC~6723 from a radius of $\sim 10$ arcseconds out to $\sim 1$\,arcminute, based on $\sim 12000$ stars. I also produced a high-quality optical-near-infrared color magnitude diagram which clearly shows the extreme horizontal branch and main-sequence knee of this cluster. / Graduate

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For unmanned aircraft systems to gain full access to the National Airspace System (NAS), they must have the capability to detect and avoid other aircraft. This research focuses on the development of a detect-and-avoid (DAA) system for small unmanned aircraft systems. To safely avoid another aircraft, an unmanned aircraft must detect the intruder aircraft with ample time and distance. Two analytical methods for finding the minimum detection range needed are described. The first method, time-based geometric velocity vectors (TGVV), includes the bank-angle dynamics of the ownship while the second, geometric velocity vectors (GVV), assumes an instantaneous bank-angle maneuver. The solution using the first method must be found numerically, while the second has a closed-form analytical solution. These methods are compared to two existing methods. Results show the time-based geometric velocity vectors approach is precise, and the geometric velocity vectors approach is a good approximation under many conditions. The DAA problem requires the use of a robust target detection and tracking algorithm for tracking multiple maneuvering aircraft in the presence of noisy, cluttered, and missed measurements. Additionally these algorithms needs to be able to detect overtaking intruders, which has been resolved by using multiple radar sensors around the aircraft. To achieve these goals the formulation of a nonlinear extension to R-RANSAC has been performed, known as extended recursive-RANSAC (ER-RANSAC). The primary modifications needed for this ER-RANSAC implementation include the use of an EKF, nonlinear inlier functions, and the Gauss-Newton method for model hypothesis and generation. A fully functional DAA system includes target detection and tracking, collision detection, and collision avoidance. In this research we demonstrate the integration of each of the DAA-system subcomponents into fully functional simulation and hardware implementations using a ground-based radar setup. This integration resulted in various modifications of the radar DSP, collision detection, and collision avoidance algorithms, to improve the performance of the fully integrated DAA system. Using these subcomponents we present flight results of a complete ground-based radar DAA system, using actual radar hardware.

Les nuages jouent un rôle important dans le cycle de l'eau et de l'énergie au sein de l'atmosphère. De plus, ils représentent l'une des principales sources d'incertitudes dans les projections des modèles de climat en raison notamment de la difficulté à paramétrer les processus qui leurs sont associés ainsi que leurs interactions avec l'environnement. Dans cette thèse nous étudions les nuages de mi-niveau qui ont été beaucoup moins étudiés que les nuages bas et les nuages hauts, en se focalisant sur l’Afrique de l'Ouest. L'Afrique de l'Ouest se caractérise par une forte saisonnalité des précipitations survenant au Sahel de juin à septembre durant la période dite de mousson. Cette période coïncide également avec le maximum annuel de la couverture nuageuse. Au travers du déploiement de la station mobile ARM (Atmospheric Radiation Measurement) durant une année en 2006 à Niamey (Niger), Bouniol et al. (2012) ont documenté les différents types de nuages observés pendant la mousson et ont montré la présence récurrente de nuages vers 6 km d'altitude dont l’impact radiatif est important dans les domaines du visible et de l'infrarouge. Dans le prolongement de cette étude, l'objectif de cette thèse est donc d'analyser plus en détails ces nuages de mi-niveau en documentant leur occurrence, leur cycle diurne et leurs caractéristiques macro- et microphysiques. Nous analysons également l'environnement thermodynamique dans lequel ces nuages sont observés ainsi que leurs effets radiatifs. D’autre part, en analysant les simulations effectuées dans le cadre du projet CMIP5, Roehrig et al. (2013) ont montré une sous-estimation de ce type de nuages dans les modèles de climat. Nous documentons plus précisément ici comment les modèles de climat et les modèles à aire limitée simulent ces nuages de mi-niveau. Afin de documenter ces nuages, des observations obtenues à partir d'instruments de télédétection active déployés sur deux sites sols : Niamey au Sahel et Bordj Badji Mokhtar au Sahara ont été combinées avec les données satellites de CloudSat et CALIPSO. Ces observations ont révélé une occurrence de ces nuages tout au long de l'année avec une prédominance durant la période de mousson. Ces nuages sont majoritairement observés dans le Sud et l'Ouest de l'Afrique de l'Ouest mais s’étendent jusqu’au cœur du Sahara. Leur présence dans cette zone désertique pourrait s’expliquer par la dynamique de la dépression thermique saharienne (Saharan Heat Low). Ces nuages sont généralement fins (la plupart ont une épaisseur inférieure à 1000 m) et sont principalement composés d'eau liquide. Une méthode de clustering appliquée à ces données nous a permis d'identifier trois types de nuages : le premier avec des bases plus basses, le deuxième avec des bases plus hautes et le dernier avec de plus fortes épaisseurs. Les radiosondages et les mesures de rayonnement nous ont permis de déterminer la stratification thermodynamique dans laquelle ces nuages sont observés ainsi que d’estimer leur impact radiatif. On observe généralement des inversions de température potentielle au sommet des nuages des deux premières familles. Dans les modèles de climat, nous avons mis en évidence une forte dispersion des occurrences des nuages de mi-niveau en termes de fréquence, de position et d’extension sur la verticale et de cycle saisonnier. L'analyse des simulations régionales indique aussi une influence de la résolution spatiale et de la paramétrisation de la convection sur la modélisation des nuages de mi-niveau simulés au Sahel et sur le Sahara. / Clouds have an important impact on the water and energy fluxes within the atmosphere. They also represent one of the main sources of uncertainties of climate models projections as a consequence of the difficulty to parametrize their associated processes as well as their interactions with their environment. In this thesis mid-level clouds are studied. Such clouds have been much less studied than low clouds and high clouds and the focus is on the West Africa. West Africa is characterized by a strong seasonality in precipitation that occur in the Sahel from June to September named the monsoon season. This period also coincides with the annual maximum of the cloud cover. Taking advantage of the one-year ARM Mobile Facility (AMF) deployment in 2006 in Niamey (Niger), Bouniol et al. (2012) documented the distinct cloud types observed during the monsoon and showed a frequent occurrence of clouds around 6 km height with an important radiative impact in the surface short-wave and long-wave domains. In the continuity of this study, the aim of this thesis is therefore to analyse in more details these mid-level clouds by documenting their occurrence, their diurnal cycle as well as their macro- and microphysical characteristics. We also analyse the thermodynamical environment in which these clouds are observed and their radiative effects. In a process-oriented evaluation of CMIP5 climate models, Roehrig et al. (2013) showed an underestimation of mid-level clouds. We document more precisely here how climate models and limited-area models simulate these mid-level clouds. To document those clouds, we combine observational data from active remote sensing instruments deployed at the two groundbased sites : Niamey in the Sahel and Bordj Badji Mokhtar in the Sahara, with merged CloudSatCALIPSO satellite. These observations reveal an occurrence of those clouds throughout the year with a predominance around the monsoon season. These clouds are preferentially observed in the Southern and Western part of West Africa but extend to the heart of the Sahara. Their presence in this desert zone may be explained by the dynamics of the Saharan Heat Low. Those clouds are usually quite thin (most of them are less than 1000 m deep) and mainly composed of liquid water. A clustering method applied to this data allows us to identify three different types of clouds : one with lower bases, one with higher bases and another with larger thicknesses. Radiosondes and radiation measurements allowed us to determine the thermodynamical stratification in which these clouds are observed as well as to estimate their radiative impact. Potential temperature inversions are generally observed at the top of the clouds of the first two families. In the climate models, we showed a strong dispersion of the occurrences of mid-level clouds in terms of frequency, location and vertical extension and seasonal cycle. Analysis of regional simulations also indicates an influence of spatial resolution and of the convection parametrization on the model ability in simulating mid-level clouds in the Sahel and in the Sahara.