Au cours de ces dernières années, les technologies de télécommunication ont fait d'énormes progrès, notamment dans les communications mobiles et les réseaux de capteurs sans fil (WSN). Pour répondre à l’augmentation de la capacité de transmission et à l’amélioration de la qualité des canaux de communications mobiles, l’élargissement de la bande de fonctionnement est nécessaire par l'utilisation d'antennes reconfigurables en fréquence. En outre, dans les applications WSN, afin de réduire les collisions, d’augmenter la distance de communication et d'optimiser la consommation, l’utilisation d’antennes reconfigurables en directivité est une bonne solution. Dans ce cadre, nos travaux de recherche ont portés sur la conception de différentes structures antennaires reconfigurables. Dans un premier temps nous avons réalisés une antenne reconfigurable à base de nouveaux éléments actifs, les digitally tunable capacitors (DTC). Ces composants sont de très bons candidats en vue d’une intégration d'antennes pour des applications communications mobiles et WSN. Ensuite nous nous sommes attachés à concevoir des structures multibande, MIMO et reconfigurables en fréquence, permettant d’augmenter la bande de fréquence de fonctionnement du système de communication, d'optimiser l'efficacité et la qualité spectrale et d'améliorer la qualité de canal. Enfin, une autre voie a été explorée, l’utilisation d’antennes reconfigurables en directivité pour des applications de WSN. Les résultats de simulation et de mesure sont également présentés dans ce chapitre. Grâce à l'utilisation de ce type de structures, la performance des WSN a été optimisée. / In recent years, telecommunication technologies have enormous progress, especially cellular communications and wireless sensor networks. To meet the demand of increasing transmission capacity, improving quality of cellular communication channels, expanding the operating band of the equipment is necessary. As passive antenna has reached the limit on increasing the operating band with the small size, the use of frequency reconfigurable antenna is a feasible solution. Besides, in the applications of WSN, to reduce collisions, increase communication distance and optimize consumption, directional reconfigurable antenna is a good proposal. In this thesis we present several reconfigurable antenna structures. Firstly, a new component is introduced; digitally tunable capacitor (DTC). Thanks to its advantages, such parts are good candidate to be integrated in the antenna for cellular communication and wireless sensor network applications. After, several antennas are introduced include multiband antenna, MIMO and frequency reconfigurable antenna, which can be used to extend the operating frequency band of the communication system, optimize spectral efficiency and quality improve channel quality. The structures of these antennas are introduced together with the results of simulation and measurement for the purpose of solving the challenges given in the future cellular communications systems. And then, the proposed approach to the design of reconfigurable directional antennas is presented. Several reconfigurable directional antennas, which are used in applications of WSN, are introduced. Thanks to the use of directional antennas reconfigurable, performance of WSN system will be optimized.

Gambia is the smallest country on the African mainland, surrounded by Senegal on all it's borders except the coastal one. Gambia faces a pressing issue with water supply shortages, along with more than one third of the world’s population. The aim of this study is to propose a system that will solve water supply shortage through a local water supply system. The method mainly consisted of a literature review, aimed to provide an overview of the subject as well as to highlight existing gaps within today’s research about rainwater harvesting systems. Furthermore, a case study was used to determine the best way to design the rainwater harvesting system. The results of the study are showcased through a tank and pipe system, where water is collected on the roof of the residential homes and stored in a polyethylene tank on the ground. The results from the survey, asking questions related to the inhabitants’ water usage habits, were analyzed and represented through a table. In Brikama rainwater can be used for laundry, cooking and watering plants. The positive effects it brings include, but are not limited to, reduction of soil erosion, restoring the ground water cycle, as well as making people become more self-sufficient. In this study, a system for Brikama can be optimized by using Solvatten technology in combination with conventional rainwater harvesting methods. The tank volume suggested by Mun and Han (2011) is a feasible premiss, however it can not be directly applied to Gambian rainwater conditions as there are differing presumptions between the reference country Korea, and Gambia. Additionally, the validity of the study is affected as the reference studies suggest using computer simulations, as well as computer models as a basis for the operational and input data. / Gambia är det minsta landet på det afrikanska fastlandet, omgivet av Senegal på alla dess gränser utom den kustnära. Gambia står inför ett akut problem med vattenbrist, tillsammans med mer än en tredjedel av världens befolkning. Syftet med denna studie är att föreslå ett system som löser problematiken med vattenförsörjning genom ett lokalt vattenförsörjningssystem. Metoden bestod huvudsakligen av en litteraturöversikt, som syftade till att ge en överblick över ämnet samt att lyfta fram befintliga luckor inom dagens forskning om system för uppsamling av regnvatten. Dessutom användes en fallstudie för att bestämma det bästa sättet att designa systemet för uppsamling av regnvatten. Resultatet av studien visas genom ett tank- och rörsystem, där vatten samlas upp på taket av bostadshusen och lagras i en polyetentank på marken. Resultatet från undersökningen, med frågor relaterade till invånarnas vattenanvändningsvanor, analyserades och representerades genom en tabell. I Brikama kan regnvatten användas för tvätt, matlagning och vattning av växter. De positiva effekter det medför inkluderar, men är inte begränsade till, minskning av jorderosion, återställande av grundvattnets kretslopp, samt att få människor att bli mer självförsörjande. I denna studie kan ett system för Brikama optimeras genom att använda Solvatten-teknik i kombination med konventionella metoder för uppsamling av regnvatten. Tankvolymen som föreslagits av Mun och Han (2011) är en genomförbar premiss, men den kan inte tillämpas direkt på gambiska regnvattenförhållanden eftersom det finns olika antaganden mellan referenslandet Korea och Gambia. Dessutom påverkas studiens validitet eftersom referensstudierna föreslår att man använder datorsimuleringar, samt datormodeller som underlag för drift- och indata.

Die vorliegende Studie entstand, um die langfristige Renditeentwicklung polnischer Aktien nach Börseneinführungen und Kapitalerhöhungen in den Jahren 1994-2008 zu untersuchen. Ein besonderes Augenmerk richtet sich dabei auf die Erkennung und Analyse der performancerelevanten Unternehmenseigenschaften sowie auf die Erklärung der festgestellten Marktanomalien mit Hilfe ausgewählter Modellansätze. Die empirischen Analysen wurden aus dem Blickwinkel eines Kleininvestors durchgeführt, wodurch die meisten Ergebnisse, neben dem wissenschaftlichen Wert, eine hohe Praxisrelevanz besitzen. Die Untersuchung von insgesamt 263 Börseneinführungen ergab, dass die Emissionsrenditen der meisten Aktien zwar signifikant positiv waren, längerfristig bauten sie sich aber ab. Am Ende des 36-sten Notierungsmonats wiesen sie insgesamt eine starke Underperformance auf. Dabei entwickelten sich die langfristigen marktbereinigten IPO-Renditen in den 90-er Jahren wesentlich schlechter, als nach der Jahrhundertwende. Die Analyse des Kursverhaltens nach 157 Kapitalerhöhungen durch Aktien- und Bezugsrechtsemissionen zeigte, dass innerhalb der dreijährigen Halteperiode die Performance der betrachteten Stichprobe von der Rendite des Gesamtmarktes nur geringfügig abweichte. Dabei entwickelten sich die Kurse von Aktien der kleineren Firmen wesentlich schlechter, als die Aktienkurse der hochkapitalisierten Unternehmen. / This study investigates the long-term stock return after initial public offerings and seasoned equity offerings occurred between 1994 and 2008. A particular attention is being paid to the identification and analysis of performance-relevant issuing firm characteristics and the explanation of the identified market anomalies by means of the preselected explanatory models. Since the empirical study was carried out from the small investor’s perspective, the majority of the obtained results provide not only a considerable scientific value, but also a strong relevance to the actual practice. The study examined 263 IPOs of common stocks and found an overwhelmingly positive initial return. However, this return vanished gradually on the long run, resulting in a high overall underperformance in 36 months after the first listing. In this respect, it is remarkable that the long-term returns of the IPO-stocks issued in the 1990s proved considerably lower than of those placed after 2000. The examination of the long-term stock price behaviour after 157 SEOs reveals only a tiny difference between the performance of the sample and the overall market return. Noteworthy is however the fact that equity issues conducted by smaller firms led usually to significantly poorer stock performance, than when equity was offered by large capitalized companies.

Vattenbesparing och alternativa lösningar för att tillgodose vattenbehovet har blivit mer aktuellt de senaste åren med torka. Regnvatteninsamling för hushållsanvändning används redan på många platser runtom i världen men är begränsad i Sverige idag. Syftet är att dels undersöka en lämplig dimensionering av ett system för regnvatteninsamling för hushåll i Jälåsa och att identifiera olika drivkrafter och hinder. Metoden i denna studie har varit dels massbalans- och effektivitetsberäkningar för att se hur mycket regnvatten som kan samlas in och dels intervjuer med två teknikleverantörer och fem kommuner för att utvärdera den juridiska, sociala och ekonomiska potentialen. Resultatet visade att tankstorlek på mellan 1000 och 4000 liter är rimligt för hushållsanvändning till toalett eller toalett och tvättmaskin och ger en effektivitet (procent av vattenbehovet som täcks av regnvatten) på mellan 83,6 % och 96,0 %. Vilken storlek som är mest lämplig beror på faktorer såsom vad regnvattnet används till, takyta, antal personer i hushållet och om first-flushbortledning används. Beräkningar visar att ungefär 19-29 % av den totala dricksvattenförbrukningen skulle kunna sparas i Järlåsa, vilket motsvarar ungefär 4 400 till 6 700 kubikmeter dricksvatten per år. Resultatet visar även att torrperioder då tanken är tom blir kortare med en större tankstorlek och det finns tydliga skillnader i volym vatten i tanken mellan olika nederbördsrika år. Enligt kommuner ansågs potentialen för regnvatteninsamling vara störst för bevattning i dagsläget men att de även var positivt inställda till annan användning såsom toalettspolning och tvättmaskin. Identifierade hinder var oro kring kontamination av dricksvatten, brist på ekonomisk lönsamhet till följd av låga dricksvattenpriser i Sverige och behov av förtydligande av krav och vilka risker som finns med regnvatteninsamling. Idag är potentialen och motivationen som störst för de som har dålig tillgång på vatten och en ökad miljömässig medvetenhet skulle kunna öka implementeringen av regnvatteninsamling i Sverige. Slutsatsen är att det finns potential för regnvatteninsamling men att det fortfarande krävs viss utveckling och mer kunskap om regnvatteninsamling under svenska förhållanden. / Water saving and alternative solutions to supply drinking water have become more important due to several consecutive droughts in recent years in Sweden. Rainwater harvesting for households is already being used in many places around the world but still has limited application in Sweden. The purpose with this study is to investigate a suitable sizing of a rainwater harvesting system in Järlåsa and to identify drivers and obstacles for implementation. The methods used in this study were firstly calculations based on mass balance and efficiency estimates and secondly interviews with two technology providers and five municipalities. The results showed that a tank size between 1000 and 4000 liters would be suitable for the purpose of supplying water for flushing toilets and for washing machines and the efficiency (percentage of water demand being met by rainwater) would be between 83,6% and 96,0%. What size tank is recommended depends on factors such as what rainwater is used for, roof area, number of people in household and whether first-flush is diverted. Results show that around 19-29%, around 4 400 to 6 700 cubic meters per year, of the total potable water consumption could be saved in Järlåsa every year using rainwater harvesting. The results also show that the dry periods, when the tank was empty, become shorter with a larger tank size and that there are distinct differences in the volume rainwater in the tank between years with varying precipitation. According to municipalities the potential was highest for irrigation purposes today but there was also potential for use in household for flushing toilets and supplying washing machines. The identified obstacles were concern regarding contamination of the drinking water supply, lack of economic profitability as a consequence of low water prices and the need for clarification of requirements and risks with rainwater harvesting. Today the potential and motivation is highest for those with an insufficient water supply and an increase in the environmental awareness could possibly enhance implementation further. The conclusion is that there is potential for rainwater harvesting but that there still is a need for some development and more knowledge regarding rainwater harvesting under Swedish conditions.

Formal state-controlled education has been a central element for social development in South Africa since the formation of the Union of South Africa in 1910. The establishment and promotion of a culture of learning and teaching is regarded as a pre-condition for high educational standards. This thesis is a study of the role of the state in the establishment of a culture of learning and teaching in South Africa from 1910 to 2004. To understand the role that the state played in promoting, or inhibiting, a culture of learning and teaching, a historical review was taken of the state's role in formal schooling in the period of the Union (1910-1947), the era of apartheid (1948-1989), the transitional period (1990-1994) and in the era of the democratic South Africa. As an ideal, the state has a responsibility to ensure the establishment of a culture of learning and teaching. The historical review revealed, however, that the state used its policies to promote political rather than educational ideologies - and in the process, there was a complete breakdown in a culture of learning and teaching. The establishment and promotion of a culture of learning and teaching towards the maintenance of high academic standards in South African state schools was the motivating force behind this study. Therefore, this study concludes with guidelines and recommendations grounded in the historical review that will hopefully promote a culture of learning and teaching in South African schools in future. / Educational Studies / D.Ed. (History of Education)

Formal state-controlled education has been a central element for social development in South Africa since the formation of the Union of South Africa in 1910. The establishment and promotion of a culture of learning and teaching is regarded as a pre-condition for high educational standards. This thesis is a study of the role of the state in the establishment of a culture of learning and teaching in South Africa from 1910 to 2004. To understand the role that the state played in promoting, or inhibiting, a culture of learning and teaching, a historical review was taken of the state's role in formal schooling in the period of the Union (1910-1947), the era of apartheid (1948-1989), the transitional period (1990-1994) and in the era of the democratic South Africa. As an ideal, the state has a responsibility to ensure the establishment of a culture of learning and teaching. The historical review revealed, however, that the state used its policies to promote political rather than educational ideologies - and in the process, there was a complete breakdown in a culture of learning and teaching. The establishment and promotion of a culture of learning and teaching towards the maintenance of high academic standards in South African state schools was the motivating force behind this study. Therefore, this study concludes with guidelines and recommendations grounded in the historical review that will hopefully promote a culture of learning and teaching in South African schools in future. / Educational Studies / D.Ed. (History of Education)