Multiengine first stages are the new trend in recent rockets. Reusability and an oxygen/methane based engine complete this picture. ArianeGroup wants to develop its own rocket following these principles. This thesis presents the study of the feeding system for a seven Prometheus engine rocket. Several ways of connecting propellant tanks to engines were proposed and analyzed. Two configurations were selected and studied with more detail. One consists of a main feeding line which is then split in seven secondary lines. The other one adds one rank of pipes to reduce the number of feeding valves. Their performances were assessed according to classic space industry drivers. Furthermore, the impact of the two solutions on the efficiency of the tank was evaluated. CAD drawings and simulation models were made and could be a base for future work if one of the systems is chosen. The study shows that a falcon 9 like feeding system is performant in terms of mass and pressure losses but another cost-effective configuration is possible and gives good results. / Första stegen med flera motorer är den nya trenden i de senaste raketerna. Återanvändbart och en syre och metan-baserad motor kompletterar denna bild. ArianeGroup vill utveckla sin egen raket enligt dessa principer. Denna avhandling presenterar studien av drivmedelsrör för en sju Prometheus-motorraket. Flera sätt att ansluta drivmedelstankar till motorer föreslogs och analyserades. Två konfigurationer valdes ut och studerades mer detaljerat. En består av en huvudlinje som sedan delas upp i sju sekundära linjer som på SpaceX Falcon 9. Den andra lösningen lägger till en rang av rör för att minska antalet ventiler. Deras prestanda utvärderades först enligt klassiska kriterier för rymdindustrin. Dessutom utvärderades de två lösningarnas påverkan på tankens effektivitet. CAD-ritningar och simuleringsmodeller gjordes och kan vara en bas för framtida arbeten om ett av systemen väljs. Studien visar att ett Falcon 9-liknande konfiguration har bättre prestanda när det gäller massa och tryckförluster men en annan kostnadseffektiv konfiguration är möjlig och ger goda resultat.

Previous research showed that combining three different optical character recognition (OCR) engines (ExperVision® OCR, Scansoft OCR, and Abbyy® OCR) results using voting algorithms will get higher accuracy rate than each of the engines individually. While a voting algorithm has been realized, several aspects to automate and improve the accuracy rate needed further research. This thesis will focus on morphological image preprocessing and morphological text restoration that goes to OCR engines. This method is similar to the one used in restoration partial finger prints. Series of morphological dilating and eroding filters of various mask shapes and sizes were applied to text of different font sizes and types with various noises added. These images were then processed by the OCR engines, and based on these results successful combinations of text, noise, and filters were chosen. The thesis will also deal with the problem of text alignment. Each OCR engine has its own way of dealing with noise and corrupted characters; as a result, the output texts of OCR engines have different lengths and number of words. This in turn, makes it impossible to use spaces a delimiter as a method to separate the words for processing by the voting part of the system. Text aligning determines, using various techniques, what is an extra word, what is supposed to be two or more words instead of one, which words are missing in one document compared to the other, etc. Alignment algorithm is made up of a series of shifts in the two texts to determine which parts are similar and which are not. Since errors made by OCR engines are due to visual misrecognition, in addition to simple character comparison (equal or not), a technique was developed that allows comparison of characters based on how they look.