Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The Electronic Systems Laboratory at Stellenbosch University is currently developing a fully 3-axis controlled Attitude Determination and Control Subsystem (ADCS) for CubeSats. This thesis describes the design and development of an Onboard Computer (OBC) suitable for ADCS application. A separate dedicated OBC for ADCS purposes allows the main CubeSat OBC to focus only on command and data handling, communication and payload management. This thesis describes, in detail the development process of the OBC. Multiple Microcontroller Unit (MCU) architectures were considered before selecting an ARM Cortex-M3 processor due to its performance, power efficiency and functionality. The hardware was designed to be as robust as possible, because radiation tolerant and redundant components could not be included, due to their high cost and the technical constraints of a CubeSat. The software was developed to improve recovery from lockouts or component failures and to enable the operational modes to be configured in real-time or uploaded from the ground station. Ground tests indicated that the OBC can handle radiation-related problems such as latchups and bit-flips. The peak power consumption is around 500 mW and the orbital average is substantially lower. The proposed OBC is therefore not only sufficient in its intended application as an ADCS OBC, but could also stand in as a backup for the main OBC in case of an emergency. / AFRIKAANSE OPSOMMING: Die Elektroniese Stelsels Laboratorium by die Universiteit van Stellenbosch is tans besig om ’n volkome 3-as gestabiliseerde oriëntasiebepaling en -beheerstelsel (Engels: ADCS) vir ’n CubeSat te ontwikkel. Hierdie tesis beskryf die ontwerp en ontwikkeling van ’n aanboordrekenaar (Engels: OBC) wat gebruik kan word in ’n ADCS. ’n Afsonderlike OBC wat aan die ADCS toegewy is, stel die hoof-OBC in staat om te fokus op beheer- en datahantering, kommunikasie en loonvragbestuur. Hierdie tesis beskryf breedvoerig die werkswyse waarvolgens die OBC ontwikkel is. Verskeie mikroverwerkers is as moontlike kandidate ondersoek voor daar op ’n ARM Cortex-M3-gebaseerde mikroverwerker besluit is. Hierdie mikroverwerker is gekies vanweë sy spoed, effektiewe kragverbruik en funksionaliteit. Die hardeware is ontwikkel om so robuust moontlik te wees, omdat stralingbestande en oortollige komponente weens kostebeperkings, asook tegniese beperkings van ’n CubeSat, nie ingesluit kon word nie. Die programmatuur is ontwikkel om van ’n uitsluiting en ’n komponentfout te kan herstel. Verder kan programme wat tydens vlug in werking is, verstel word en vanaf ’n grondstasie gelaai word. Grondtoetse het aangedui dat die OBC stralingverwante probleme, soos ’n vergrendeling (latchup) of bis-omkering (bit-flip), kan hanteer. Die maksimum kragverbruik is ongeveer 500 mW en die gemiddelde wentelbaankragverbruik is beduidend kleiner. Die voorgestelde OBC is dus voldoende as ADCS OBC asook hoof-OBC in geval van nood.

Abstrakt I den svenska sjökaptensutbildningen ingår 360 dagars fartygsförlagd utbildning. Under utbildningen ombord finns en utsedd handledare till hjälp för att utveckla och stötta studenten. Syftet med denna studie är att belysa handledares upplevelser av studenters förmåga att hantera tiden ombord, uppfattningen om den egna rollen som handledare samt synen på upplägget av den fartygsförlagda utbildningen. Studien utgörs av en kvalitativ intervjustudie där sju yrkesverksamma handledare från fyra olika rederier har intervjuats. Valet av en kvalitativ studie bestående av intervjuer gjordes för att kunna fånga respondenternas uppfattningar och upplevelser samt skapa en möjlighet för utvecklade resonemang. Studien avgränsas till svenska handledare för sjökaptensstudenter på svenskägda produkttankfartyg. Studiens resultat visar att handledarna är positiva till handledarskapet och de möjligheter som detta medför för studenterna men också för möjligheten att som handledare kunna påverka sina framtida kollegor. Resultatet visar också att det finns möjligheter för studenterna att kunna få ut mer av sin praktik. Ett exempel på detta är att utnyttja lediga söndagar till att fördjupa sina kunskaper, lediga dagar som för varje student är sammanlagt 52 dagar. / Abstract Within the Swedish Master Mariner programme 360 days of onboard training are included. A supervisor is designated on board during the internship, with the task of helping to develop and support the student. The aim of this study is to illuminate: the supervisor’s experiences of the student’s ability to handle their time on board, their thoughts about their own role, and the arrangement of the onboard training. This is a qualitative study in which seven supervisors, active in four different shipping companies were interviewed. The selection of this type of study was based on the fact that interviews would capture the respondents’ perceptions and experiences, and at the same time allow for them to develop their reasoning. The selection of respondents in this study was limited to Swedish supervisors for Master Mariner students employed in Swedish-owned product tankers. The study reveals that the supervisors are positive about their role and the opportunities that the training generates for the students, and also about their own influence on their future colleagues. The study also reveals that students may gain more from the internship by utilising their rest days. Each student has a total of 52 rest days during the internship.

Dans ce mémoire, nous présentons l'étude d'un senseur inertiel à ondes de matière embarqué dans un avion effectuant des vols paraboliques.Une source laser bi-fréquence robuste et compacte permettant de refroidir et d'interroger simultanément des atomes de 87Rb et 39K a été développée. Elle est basée sur des lasers télécom asservis sur un peigne de fréquences optique et doublés en fréquence. L'utilisation de composants optiques fibrés permet de rendre le système intrinsèquement résistant aux vibrations et aux fluctuations thermiques. Le dispositif a été validé en vol par l'obtention d'un double piège magnéto-optique.Nous avons utilisé la source laser pour faire fonctionner un interféromètre à atomes froids de 87Rb dans l'avion. Un accéléromètre mécanique auxiliaire permet d'augmenter la dynamique du capteur atomique et d'enregistrer des franges d'interférences malgré le niveau élevé des fluctuations d'accélération. Le senseur hybride ainsi réalisé a une résolution de 4.10-3 m.s-2.Hz-1/2, environ 100 fois plus faible que le niveau des vibrations dans l'avion.Dans la perspective de réaliser un test du principe d'équivalence en microgravité avec des atomes froids, nous étudions enfin de manière théorique le fonctionnement d'un interféromètre différentiel et nous intéressons à l'influence de certains effets systématiques. / In this thesis, we report on the study of a matter-wave inertial sensor, operated in an airplane carrying out parabolic flights.We have developped a compact and robust dual-wavelength laser source to cool and interrogate 87Rb and 39K atoms. It is based on frequency-doubled telecom lasers locked on a femtosecond optical frequency comb. The use of fibered optical components makes the setup intrinsically immune to vibrations and thermal fluctuations. The laser source was validated in flight by obtaining a double-species magneto-optical trap.We have used the source to carry out airborne measurements with an atom interferometer operating with cold 87Rb atoms. An auxiliary mechanical accelerometer makes it possible to increase the atomic sensor's dynamic range, and to record interference fringes despite the high level of acceleration fluctuations. This hybrid sensor has a resolution of 4.10-3 m.s-2.Hz-1/2, which is approximately 100 times lower than the typical vibration level in the plane.In the perspective of testing the equivalence principle with cold atoms in microgravity, we finally theoretically study the operation of a differential interferometer and investigate the influence of some systematic effects.

Submitted by Joel de Lima Pereira Castro Junior (joelpcastro@uol.com.br) on 2016-07-25T19:41:35Z No. of bitstreams: 1 Cristina Kurtz.pdf: 4377996 bytes, checksum: 036e5733657fbaf2139577f5d1bfd54d (MD5) / Approved for entry into archive by Biblioteca de Administração e Ciências Contábeis (bac@ndc.uff.br) on 2016-08-01T18:06:16Z (GMT) No. of bitstreams: 1 Cristina Kurtz.pdf: 4377996 bytes, checksum: 036e5733657fbaf2139577f5d1bfd54d (MD5) / Made available in DSpace on 2016-08-01T18:06:16Z (GMT). No. of bitstreams: 1 Cristina Kurtz.pdf: 4377996 bytes, checksum: 036e5733657fbaf2139577f5d1bfd54d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os portos brasileiros representam quase a totalidade do volume do comércio exterior do Brasil. As atividades deste setor, portanto geram grande quantidade de resíduos sólidos que acabam por impactar meio ambiente. O presente trabalho tem como objetivo analisar as práticas atuais de gerenciamento de resíduos oriundos especificamente das embarcações acostadas nos portos marítimos brasileiros, bem como a legislação nacional vigente, e examinar se contribuem efetivamente para a correta gestão. A pesquisa teve como base as seguintes ferramentas metodológicas: levantamento bibliográfico, de diversas fontes como relatório de atividades, planos e programas de empresas, operadoras e terminais, documentos internos do porto, publicações de órgãos públicos, artigos científicos, manifestos de resíduos e outros; a identificação e a análise de documentação, conteúdo e da legislação aplicável; as pesquisas junto a instituições de ensino e pesquisa especializados no tema; o estudo de casos múltiplos, no caso vinte e dois portos ao longo da costa brasileira; e o levantamento de informações de fontes internacionais. Os portos selecionados, que serviram de alicerce para o estudo, tiveram como base o Programa de Conformidade do Gerenciamento de Resíduos Sólidos e Efluentes nos Portos Marítimos Brasileiros, desenvolvido pelo IVIG/COPPE/UFRJ, e estão localizados em todas as regiões da costa brasileira: Norte, Nordeste, Sudeste e Sul. Os resultados obtidos demonstram que as atuais práticas de gerenciamento dos resíduos de bordo não necessariamente contribuem para uma correta administração. A legislação nacional vigente sobre o objeto é genérica e não regulamenta especificamente a atividade potencialmente geradora de resíduos oriundos de embarcações acostadas. A presente dissertação confirma ainda a existência de conflitos nos procedimentos de retirada dos resíduos nos portos brasileiros, inexistindo um padrão em nível nacional. Deste modo, existem mecanismos e ferramentas específicas para o gerenciamento deste resíduo específico, tais como classificação, coleta e padronização que podem proporcionar melhoria na gestão de resíduos. / The Brazilian ports represent almost the totality of the volume of Brazil´s international trade. Therefore, this sector´s activities generate a great amount of solid waste that end up having an impact in the environment. The present study aims to analyze the current practices of waste management deriving specifically from ships docked in the Brazilian sea ports, as well as the existing national law, and to examine if they contribute effectively to the correct management. The base of the research were the following methodological tools: bibliographical survey from several sources such as activities report, enterprise‘s plans and programs, operators and terminals, internal documents of the port, public bodies publications, scientific articles, waste manifests and others; identification and analysis of documentation, content and applicable legislation; researches with educational institutions and researches specializes in the subject, study of multiple cases, that is twenty-two ports along the Brazilian coastline; and the survey of information from international sources. The selected ports that served as foundation for this study were based on the Management of Effluent and Solid Waste in the Brazilian Seaports Compliance Program, developed by the IVIG/COPPE/UFRJ, and are located in all regions of the Brazilian coastline: north, northeast, southeast and south. The results obtained demonstrate that the current practices of onboard waste management don‘t necessarily contribute to a correct management. The existing national law concerning the object is generic and doesn‘t regulate specifically the potentially generating activity waste deriving from ships docked. The present study confirms the existence of conflicts in the waste removal procedures at the Brazilian ports, not existing a pattern on a national level. Thus, there are specific mechanisms and tools for the management of this specific waste, such as classification, collection and standardization that can provide an improvement in the waste management.

Cette thèse s’inscrit dans le programme de recherche beyond the sea® visant à développer la traction de navire de commerce par des kites géants. Le but est d’utiliser l’énergie du vent, et ainsi de réduire la consommation de carburant des navires et réduire les émissions polluantes. Un tel projet demande de nombreux développements et actions scientifiques, en particulier pour prédire le comportement des cerfs-volants géants et des navires associés. Pour cela des modèles sont développés, mais ces modèles doivent être confrontés à des mesures pour en estimer la validité. Cette thèse a donc pour objectif de mesurer les interactions entre le kite et le navire, à une échelle limitée par rapports aux navires visés par le programme global. Des mesures ont donc été réalisées sur un navire de pêche de 13 m, puis sur un bateau expérimental de 6 m spécialement conçu à cet effet. De plus, des mesures ont aussi été menées à terre pour évaluer uniquement les performances du kite. Chacune de ces campagnes expérimentales mettait en oeuvre un dispositif de mesure complexe, ainsi qu’un système automatique de contrôle du vol du kite. En plus de fournir des données de qualité à destination de la science, les outils développés au cours de cette étude peuvent être utilisés directement par les partenaires industriels du projet beyond the sea®. / This study is part of the research program beyond the sea® aiming to develop kites as auxiliary propulsion devices for ships. The goal is to use the energy of the wind to save fuel and reduce harmful emissions. Such a project needs numerous developments and scientific actions, particularly to model the behavior of giant kites and associated ships. However these models must be compared to measurements to assess their validity. This study is then focus on the measurements of the interaction between kites and ships, at a limited scale in comparison to the real scope of the project. Thus measurement campaigns were carried out on a 13-meter long trawler, and on a 6-meter long experimental platform specifically designed. Another experimental campaign was also carried out onshore to assess the aerodynamic specs of the kite. Each of these three campaigns was based on a complex experimental set-up, including an automatic kite control system. In addition to provide a valuable data set for further scientific analyses, this study provided also tools which can be used by the industrial partners of the beyond the sea project®.

The upcoming level 3 generation of self-driving vehicles will be characterized by the freedom of not having the driver’s hands on the steering wheel. This acquired freedom is posing new challenges on the traditional passenger comfort paradigm as the drivers will spend a higher amount of time doing non-driving tasks (NDRT). Certain constraints must be imposed as the level 3 generation systems will not be able to drive all the time without active feedback from the user. The driver needs to stay active enough to do takeover in a situation where it is needed to. What effect will different NDRT have on the behavior of a driver in a self-driving car? In our low fidelity driving simulator, we tested different simple actions (e.g. playing a simple 2D game). We then evaluated them based on their accident avoidance and situation awareness in the post-transition period. The results show a significant difference between the reaction speeds of the drivers before and after an active task.

Due to the usage of complicated platforms and current high-performance space computing technology, onboard processing in small satellites is expanding. Space-cloud payload processors with Commercial Off-The-Shelf (COTS) components, that are required to be radiation-tolerant, are used to perform the onboard processing. In this thesis, the research will aim to increase the dependability of a generic space-cloud payload processor through its Solid State Drive (SSD) storage unit. To achieve this, a more dependable NAND-flash-based SSD Redundant Array of Independent Disc (RAID) storage system is designed and tested. The reliability of NAND-flash-based SSDs can suffer wear-outs due to increased Program/Erase (P/E) cycles, making them more prone to radiation effects. These radiation effects are considered non-destructive events in the form of bit errors (both single bit-flip and multiple bit-flips). Therefore, making the storage system more dependable involves increasing its reliability against non-destructive events and developing analytical models that account for the considered dynamic of the SSD RAID. The challenge that comes with achieving the aim of this thesis is twofold. First, to explore different RAID levels such that a combination of RAID levels can be incorporated into one SSD for better reliability than a RAID-1 setup. Hence, in this thesis, a RAID array of several SSDs is not considered. Furthermore, the combinations of RAID levels need to account for mixed-critical data. Second, to demonstrate, via simulation and analytical models, the impact on the reliability of the storage system. A comparison study is also undertaken due to the support that the Fourth Extended (Ext4) file system or Zettabyte File System (ZFS) may give to enhance the storage system, and since little research exists that compares the file systems in some feature categories. The solution is a RAID-5 + 6 storage system that is Error Detection And Correction (EDAC) protected by Hamming codes and Reed Solomon (RS) codes. Low-critical data is stored using RAID-5 whereas high-critical data is stored using RAID-6. The simulation of the storage system proves that low-critical stripes of data achieve single fault tolerance whereas high-critical stripes of data tolerate a maximum of 5-bit burst errors. In parallel, several Continuous Time Markov Chain (CTMC) models are analysed, which show that the proposed solution is indeed highly reliable. The comparison study is carried out in a systematic way, and the findings are established as substantial,i.e., ZFS provides greater storage system support. In summary, the results of creating the storage system and analysing it suggest that incorporating RAID-5 and RAID-6 offers better SSD RAID reliability than RAID-1. / Användningen av komplicerade plattformar och aktuell högpresterande rymdberäkningsteknik expanderar onboard-processing i små satelliter. Space-Cloud lösningar med kommersiellt tillgängliga komponenter som är toleranta mot strålningar i rymden används för att utföra onboard-processing. I detta examensarbete syftar forskningen till att förbättra tillförlitligheten hos en generisk rymd dator genom dess SSD-lagringsenhet. För att uppnå detta har ett mer tillförlitligt lagringssystem bestående av NAND-flash och RAID designats och testats. Tillförlitligheten hos NAND-flash-baserade SSD:er kan försämras då dessa kan drabbas av slitage på grund av ökade P/E cykler, vilket gör dem mer benägna för strålningseffekter. Dessa strålningseffekter anses vara icke-destruktiva i form av bit-fel (både enskilda bit-flippar och flera bit-flippar). Med denna anledning görs lagringssystemet mer tillförlitligt för att tolerera icke-destruktiva händelser. Utöver detta, utvecklas analytiska modeller som tar hänsyn till den betraktade dynamiken i SSD RAID. Utmaningen som följer med att uppnå syftet med denna avhandling är tvådelad. För det första, för att utforska olika RAID-nivåer så att en kombination av RAID-nivåer kan inkorporeras i en SSD för bättre tillförlitlighet än RAID-1. Således övervägs inte en RAID-array av flera SSD:er i denna avhandling. Dessutom måste kombinationerna av RAID-nivåer ta hänsyn till data av olika kritikalitet. För det andra, för att genom simulering och analytiska modeller indikera påverkan på lagringssystemets tillförlitlighet. En jämförelsestudie genomförs också på grund av stödet som filsystemen Ext4 eller ZFS kan ge för att förbättra lagringssystemet och eftersom det finns lite forskning som jämför filsystemen i några funktionella kategorier. Lösningen baseras på ett RAID-5+6 lagringssystem som är skyddat av Hamming-koder och RS koder för att upptäcka fel och korrigera dem. Lågkritisk data lagras med RAID-5 medan högkritisk data lagras med RAID-6. Simuleringen av lagringssystemet visar att lågkritiska datasektioner uppnår en fel tolerans mot enskilda bit-flippar medan högkritiska datasektioner kan tåla maximalt 5 bit-flippar. Samtidigt analyseras flera CTMC modeller som visar att den föreslagna lösningen verkligen är mycket tillförlitlig. Jämförelsestudien utförs på ett systematiskt sätt och resultaten fastställs som betydande, det vill säga att ZFS ger större stöd för lagringssystemet. Sammanfattningsvis antyder resultaten av att skapa lagringssystemet och analysera det att inkorporering av RAID-5 och RAID-6 erbjuder bättre tillförlitlighet för SSD RAID än RAID-1.

No description available.

This thesis presents a novel, cost-effective method for mapping the pressure distribution on a rotating cylinder in cross flow, a phenomenon central to the Magnus effect. Utilizing commercial-off-the-shelf (COTS) micro-electromechanical system (MEMS) pressure sensors, a high-resolution data acquisition system was developed and integrated into a rotating cylinder model. Compared to traditional approaches, such as slip rings or one-off designs, this method proved significantly cheaper and faster while achieving comparable or superior resolution. The experimental setup, including a modified continuous rotation technique and adaptable model design, facilitated rapid testing across a broad range of Reynolds numbers and reduced frequencies, exceeding the scope of existing literature. This provided an unprecedentedly detailed view of pressure distributions under both steady and unsteady flow conditions. The validated experimental methodology, applicable to arbitrary bluff body shapes and attitudes, has the potential to significantly accelerate research into unsteady aerodynamics. Moreover, the low-cost, adaptable nature of the setup allows its integration into educational settings, providing students with hands-on experience in experimental fluid mechanics and data acquisition.

Cette recherche doctorale s'intéresse à la culture matérielle maritime et plus particulièrement à un mobilier de bord, à usage individuel et collectif, dont les modalités d’acquisition restent très généralement marginales. Pour cela, la céramique, produite entre le XVe et le XVIIIe siècle provenant de dépotoir portuaire et d'épave répartis majoritairement sur le littoral nord-méditerranéen français, constitue notre support d’analyse. Considérée comme un artéfact majeur des contextes archéologiques, la céramique permet d'appréhender les échanges maritimes, la composition du vaisselier et une part de l'instrumentum de bord. L'approche diachronique de cette recherche donne lieu à une cartographie exhaustive de la répartition des épaves et des dépotoirs portuaires nord-méditerranéens afin de caractériser les aires de diffusion des céramiques rencontrées. Ces dernières, une fois analysées d’après une méthodologie adaptée aux problématiques de la recherche et confrontée aux sources écrites, nous fournissent de précieuses informations sur les relations et les usages en Méditerranée occidentale, selon les séquences chronologiques considérées et permettent de porter un autre regard sur des instants du quotidien des gens de mer. / Our doctoral research deals with maritime material culture and especially in onboard furniture, used in a personal and collective way, whose modalities of acquisitions are usually marginal. Our analysis support is composed of ceramics produced between the XVth and the XVIIIth century coming from harbour dumpsite and shipwreck generally located on the north mediterranean French coast. Think as one major archaeological artéfact, ceramic may help to understand maritime exchanges, dishes and one part of the onboard instrumentum. The diachronic approach of this research leads to a repartition map of harbour dumpsite and shipwreck in north Mediterranean French coast. Our study shed light on the areas of ceramics distribution. We analyzed ceramics according to an adapted issue methodology and confronted with written sources. The results gives us valuable information on relations and uses in western Mediterranean, according to the sample chronology considered and allow us to better understand the everyday life seafarers.