Doctor of Philosophy (PhD) / This thesis presents the development of new techniques for measuring the mean redshifted 21 cm line of neutral hydrogen during reionization. This is called the 21 cm cosmological reionization monopole. Successful observations could identify the nature of the first stars and test theories of galaxy and large-scale structure formation. The goal was to specify, construct and calibrate a portable radio telescope to measure the 21 cm monopole in the frequency range 114 MHz to 228 MHz, which corresponds to the redshift range 11.5 > z > 5.2. The chosen approach combined a frequency independent antenna with a digital correlation spectrometer to form a correlation radiometer. The system was calibrated against injected noise and against a modelled galactic foreground. Components were specified for calibration of the sky spectrum to 1 mK/MHz relative accuracy. Comparing simulated and measured spectra showed that bandpass calibration is limited to 11 K, that is 1% of the foreground emission, due to larger than expected frequency dependence of the antenna pattern. Overall calibration, including additive contributions from the system and the radio foreground, is limited to 60 K. This is 160 times larger than the maximum possible monopole amplitude at redshift eight. Future work will refine and extend the system known as the Cosmological Reionization Experiment Mark I (CoRE Mk I).

Les réseaux IEEE 802.11 sont, entre autres, très souvent utilisés pour se connecter à l'Internet car ils proposent une solution bon marché, facile à déployer et qui supporte la mobilité. Dans cette thèse nous considérons quatre différents aspects de la qualité de service (QoS) dans ces réseaux :<br />- Différentiation de service : Le protocole IEEE 802.11 actuel n'a aucun support de la QoS. Ainsi, tous les terminaux partagent équitablement le débit disponible. Nous proposons des mécanismes de différentiation de services au niveau MAC. Nous développons et simulons plusieurs mécanismes de différentiation pour IEEE 802.11.<br />- Environnements bruités : IEEE 802.11 utilise des fenêtres de contention pour résoudre l'accès multiple des terminaux au canal. Un terminal double la taille de sa fenêtre de contention à chaque perte de paquet.<br />Cette stratégie diminue les collisions au canal, mais augmente le surcoût des paquets, diminuant ainsi le débit. Cependant, les pertes peuvent également être dues à du bruit sur le canal. L'augmentation de la fenêtre de contention peut alors être très néfaste en termes de performance. Il convient d'augmenter la fenêtre de contention uniquement si la perte à été produite par une collision. Nous proposons une stratégie d'adaptation de la fenêtre de contention qui varie selon l'estimation de la cause de perte des paquets. <br />- Environnements congestionnés : Après chaque bonne transmission de paquet, IEEE 802.11 remet la taille de la fenêtre de contention à zéro. Cependant, dans un environnement congestionné la charge sur le canal varie lentement, et un terminal risque d'avoir le même taux de collisions et de retransmissions. Nous proposons un mécanisme basé sur une réduction de la taille de la fenêtre de contention plus lente, pouvant mieux éviter les collisions et les retransmissions. Ceci présente un gain considérable en terme de débits et de consommation d'énergie.<br />- Réseaux ad-hoc: Dans un réseau ad-hoc les paquets sont routés suivant des chemins multi-saut. Ainsi le routage est coopératif entre les différents nœuds, et le débit utile moyen disponible à chaque nœud dépend du nombre total des nœuds, des interférences et des collisions. Nous proposons un mécanisme de contrôle de débits aux sources, basé sur l'estimation des débits et des délais, pouvant optimiser les débits utiles ainsi que la consommation d'énergie.

La formation des étoiles massives reste, à ce jour, encore mal connue à cause de l'extrême quantité d'énergie que ces étoiles dégagent, limitant en conséquence leurs masses théoriques et contredisant les observations de ce type d'étoile. Les observatoires du futur (en particulier l'observatoire spatial Herschel) vont tenter de répondre à cette problématique grâce notamment aux émissions moléculaires de l'eau. L'analyse précise et correcte de ces données, dans l'avenir, nécessite donc dès aujourd'hui un travail associant des observations et des modélisations des objets concernés. C'est dans ce but que cette thèse a consisté en l'élaboration d'une méthode de modélisation dite « globale » d'objets proto-stellaires massifs (proto-amas ou cœurs denses massifs). Celle-ci a permis une description physique et une étude chimique des multiples cœurs denses massifs étudiées, et a ouvert de nombreuses voies vers des aspects évolutifs. Elle a également donné des indices pour affiner le programme d'observation en temps garanti WISH des raies moléculaires de l'eau et confirmé le rôle clef de cette molécule pour la compréhension de la formation des étoiles massives.

Je présente et j'analyse dans ma thèse des observations de l'émission dans l'infrarouge proche de transitions rovibrationelles de H2 dans des régions de formation stellaire. Le sujet principal de ce travail concerne de nouvelles observations du nuage moléculaire d'Orion (OMC1) et en particulier de la région BN-KL. Les données sont constituées d'images des raies individuelles de H2 obtenues à haute résolution spatiale avec le Telescope Canada-France-Hawaii et avec l'ESO VLT. Grâce à la haute résolution spatiale du VLT il est possible d'analyser en détail (jusq'à 60 UA ~0.''13) des objets individuels dans cette région. De plus, j'ai analysé l'émission de H2 et [FeII] dans des écoulements (« outflows ») présents dans deux nuages sombres (les globules de Bok BHR71 et BHR137) ainsi que dans un « blob » à haute excitation dans le grand nuage de Magellan (N159-5). Ici les données sont constituées de spectres en fente longue obtenus à l'ESO-VLT. Pour réaliser ce travail j'ai tout d'abord calculé une grille complète de modèles de chocs composée de ~25 000 simulations (correspondant à 400 Go, environ). Ces modèles qui sont les plus récents comportent un grand nombre de paramètres libres qui peuvent être ajustés. Une grande partie demon travail a été d'analyser les résultats de cette grille avant de les mettre en ligne. En effet les résultats ne sont pas tous crédibles, et il m'a donc fallu de développer des méthodes pour les vérifier. Mais avec une bonne compréhension du modèle et un solide sens de la physique des chocs, il est maintenant assez facile d'interpréter les données sur H2 et [FeII]. Les modèles me permettent ensuite de prédire les conditions physiques à grande échelle dans OMC1, par exemple la densité, la vitesse des chocs, l'intensité du champ magnétique, etc. En général la densité du milieu avant le choc est ~105-107 cm-3 et la vitesse de choc est dans la gamme 10-40 km.s-1. Un autre résultat très intéressant de mon travail est le développement d'une nouvelle méthode pour analyser les chocs en arc (« bow shocks ») observés à une haute résolution spatiale. Pour un choc en arc isolé je prédis une vitesse de choc de ~50 km.s-1 et une densité avant le choc de 5×105 cm-3. La vitesse 3D a été mesurée très récemment à 55 km.s-1. Cela donne une confirmation indépendante de nos résultats.

Spectroscopic observations of cold and dense interstellar clouds show the presence of "dirty ice" mantles on dust grains, mainly composed by water molecules. These ices are enriched by the presence of other simple species that are either formed by surface reactions or accreted from the gas phase. While there is quite a general consensus that interstellar water ice is mainly amorphous, its morphology (porous or compact) still remains poorly known. Morphology is important due to its influence both on the catalytic efficiency of grain surfaces and on the release to the grain of the fraction of the formation energy of species, as shown by laboratory simulations of molecular hydrogen formation. Ice porosity may be identified through the weak infrared absorption features (~ 2.7 μm) showing the presence of dangling bonds on the pore surface. To our knowledge, there has been to date no detection of such absorptions in the infrared spectra of interstellar ices, perhaps suggesting that they may have a compact nature. It has been already investigated that interstellar porous ice may be compacted by the transient heating of stellar radiation and cosmic ray bombardment. In this thesis I report an experimental work, performed using FORMOLISM (the experimental apparatus at the University of Cergy-Pontoise - France), that shows relevant changes in the ice morphology following atomic hydrogen exposure. In particular, it is shown that a thin highly porous ice film is gradually changed into a more compact structure. This is probably due to the transient heating caused by the energy released to the ice during H2 formation. Such a process may also produce in the interstellar space compact amorphous ice mantles concurrently with the other envisaged processes. Moreover, I have experimentally analyzed the morphology of the just formed water ice. Analysing one of the possible mechanism of water formation (the pathway H + O2) under conditions mimicking those found in a molecular cloud, we have found that the water just synthesized has a non-porous structure. Indeed, the layers of water formed in this way show the kinetic characteristics typical of a compact (non-porous) ice, as for instance the D2 TPD peak position.

<p>This thesis contributes to the research field information logistics. Information logistics aims at improving information flow and at reducing information overload by providing the right information, in the right context, at the right time, at the right place through the right channel.</p><p>Ontologies are expected to contribute to reduced information overload and solving information supply problems. An ontology is created to form some kind of shared understanding for the involved stakeholders in the domain at hand. By using this semantic structure you can further build applications that use the ontology and support the employee by providing only the most important information for this person.</p><p>During the last years, there has been an increasing number of successful cases in which industrial applications successfully use ontologies. Most of these cases however, stem from large enterprises or IT-intensive small or medium-sized enterprises (SME). The current ontology development methodologies are not tailored for SME and their specific demands and preferences, such as that SME prefer mature technologies, and show a clear preference for to a large extent standardised solutions. The author proposes a new ontology development methodology, taking the specific characteristics of SME into consideration. This methodology was tested in an application case, which resulted in a number of concrete improvement ideas, but also the conclusion that further specialisation of the methodology was needed, for example for a specific usage area or domain. In order to find out in which direction to specify the methodology a survey was performed among SME in the region of Jönköping.</p><p>The main conclusion from the survey is that ontologies can be expected to be useful for SME mainly in the area of product configuration and variability modelling. Another area of interest is document management for supporting project work. The area of information search and retrieval can also be seen as a possible application field, as many of the respondents of the survey spend much time finding and saving information.</p>

<p>The business climate of today, with increasing globalization, has resulted in structural changes in the commercial and industrial sectors. As a result, many large companies have moved their production abroad. Therefore the smaller companies have become increasingly important for growth and employment nationally. Small businesses are a significant contributor to the well-being of nations and small and medium-sized enterprises (SMEs) play an important role for Sweden, both in terms of economic contribution and employment.</p><p>Success has been discussed and investigated for a long period of time and the question is how it should be defined and measured. Many theories have been produced including different definitions and research methods. For this thesis, however, success is defined as the growth and financial performance of a firm measured in volume growth, relative change in net turnover, and value growth, relative change in equity. As a side condition, profit margins must be positive for a company to be classified as successful. This thesis hence aims to determine which factors influence the success of small and medium-sized enterprises in Sweden and how they influence the success of these enterprises.</p><p>Eleven manufacturing SMEs, seven successful and four unsuccessful, were investigated and analyzed separately and then compared with one another in an attempt to determine which specific factors contributed to their respective performance. The four unsuccessful companies were included in the investigation for comparison to be able to identify the specific factors for successful companies. The analyses resulted in the following areas: Organization, Vision and Strategy, Characteristics of the CEO, Core Competences, Recruiting, Product Development and Innovations and Market. Among these factors Vision and Strategy, Core Competences and Customer Interaction were identified as the factors that have the greatest impact on success. Additionally, two clear relations between factors could be determined, i.e. between Clear vision and strategy and Defined culture as well as a relation between Flexibility and Customer Interaction.</p><p>The conclusions are generalizable to all manufacturing SMEs in Sweden since the sample selection is representative for the target population. Furthermore, the success factors could be applied to companies abroad as well if the business climate and the conditions are similar. Whether the factors can be applied to firms that act within different SNI-codes (Swedish Standard Industrial Classification) besides manufacturing is yet to be proved.</p><p>For further research we suggest a deeper investigation, where the information is obtained from more than one sources within the company. Also, the external networks of the company could be of interest to interview. Other aspects to investigate further would be potential differences between small and medium-sized firms and whether or not the results are applicable for other industries.</p>

<p>Wireless communication is facing one of the fastest developments of the last years in the fields of technology and computer science in the world. There are several standards that deal with it. In this work, the IEEE standard 802.11a, which deals with wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, is going to be discussed in detail. </p><p>Taking this into consideration, PHY specifications and its environment are going to be studied. </p><p>The work that the ISY department at the Institute of Technology of the Linköping University has proposed is to design a PHY layer implementation for WLANs, in a CPU, using MATLAB/Simulink and in a DSP processor, using Embedded Target for C6000 DSP and Code Composer Studio and, once implemented both, to perform and analyse the performance of the system under those implementations.</p>

<p>Hilma af Klint är en av de mest uppmärksammade kvinnliga konstnärerna ur sin tid trots ellerkanske på grund av att hennes bilder inte uppmärksammades förrän 45 år efter hennes död. Detta faktum samt att en stor del av hennes livsverk var andliga, mediumstiskt framställda bilder gör dets vårt att placera bilderna i en konsthistorisk kontext. I denna C-uppsats undersöker jag framförallttre aspekter runt Hilma af Klints och hennes livsverk med tempelbilderna. Jag har med hjälp avqueerteorier undersökt hur utanförskap och avsaknad av sexualitet kan ha påverkat Hilma af Klintsbildskapande. Jag har intresserat mig för en roll som Hilma af Klints bilder tycks ha, som kartor och manualer för andra andliga sökare. Hon var en bildskapare som levde utanför de rådande normerna både vad gäller bildskapandet och personligen och gick sin egen väg vilket gör henne till eninspiratör för de som kommer efter henne. Hilma af Klint levde asketiskt helt hängiven sitt uppdrag. Allt tyder på att hon levde utan partner i avhållsamhet trots att hennes viktigaste budskap var ”dualen” som innebär att mannen och kvinnan är två halvor av samma själ som letar efter varandraför att återförenas. I bilderna framställs dualen som en man och en kvinna medan i Hilma af Klints anteckningar visar det sig att hon upplevde en kvinna som hennes dual under en tid medan det vid ett annat tillfälle var en man ur andevärlden. En annan aspekt som jag undersökt är hur bilderna uppfattas när de inte hamnar i den tempelmiljö som de skapades för och istället betraktas som autonoma. Tidigare forskning innehåller inga bildanalyser vilket jag tagit fasta på och anser vara enviktig del av att förstå bilder som autonoma, en viktig aspekt av modernistisk konst. I dessa bildanalyser finner jag att bilderna har mycket att ge om de tillåts stå fria från det sammanhang somde skapandes ur. Ytterligare en aspekt som jag undersökt är hur dessa bilder behandlas i konsthistorieskrivningen. Hilma af Klint upplevde sig som en förmedlare av bilder från andliga mästare, hennes egen roll som subjekt var sekundär. Trots detta är det personen Hilma af Klint som fått mest utrymme i historieskrivningen. Det finns en gängse bild av Hilma af Klint som en pionjär inom den abstrakta konsten vilket kan ses som problematiskt av flera skäl, inte minst det faktum att bilderna, enligt henne själv, var förmedlade till henne i syfte att upplysa mänskligheten. Jag har funnit att det tyvärr inte är helt enkelt att uppleva Hilma af Klints bilder i original. Tempelbildernavar tänkta att smycka ett tempel som aldrig kom att byggas. Ingen, inte ens Hilma af Klint själv har sett Tempelbilderna samlade i sin tänkta miljö. Däremot finns det planer på ett museum i Ytterjärna som enligt uppgift ska visa hela Hilma af Klints livsverk.</p>

<p>The business environment is changing rapidly, becoming very competitive and challenging for all firms, and particularly for small and medium enterprises (SMEs). As innovation and new product development represent valuable sources for SMEs’ future sustainability and development, making these processes more effective is essential. Previous literature, with the focus on large firms, underlined the importance of efficiently managing the early period of new product development (NPD), as this can reduce the product’s time to market and increase its performance. For this reason, contributing to a developed understanding of the challenges of medium-sized firms in managing this phase, the fuzzy front-end (FFE) of NPD, is the aim of this study.</p><p>The theoretical framework of this study combines prior theories that relate to the difficulties, shortcomings, challenges that SMEs meet during the whole NPD process, including FFE, and theories that resulted from research on FFE in large firms. The structure is based on four elements referring to managing the idea generation process, new product development team, evaluation of product concept feasibility, and the organization of FFE.</p><p>A qualitative strategy and a research design with two case studies on high-tech, medium-sized manufacturing firms were used in reaching the purpose of this study. This methodology choice reflects the explorative purpose of this research. The empirical data are mainly primary data, collected during three interviews with development managers and a product developer, completed as well with secondary data like general company information, collected from companies’ websites.</p><p>The analysis of empirical findings revealed some relevant conclusions, which can bring value to the research area, and also to the practice. Our findings show that lack of communication with customers during the whole FFE phase, collecting limited or inaccurate information to be processed during this phase, finding the right formalization degree of FFE activities, determining the complexity of the product concept, and assessing external technology and expertise, represent the main challenges faced by medium-sized firms in the FFE of NPD.</p><p>The study’s practical relevance consists in the advices and solutions suggested to managers for overcoming the challenges of the FFE phase and improving their results in the development projects. The theoretical implications reflect the importance of organizational size variable in association with the challenges of FFE.</p><p>The sample of only two cases and the quality of the empirical data collected from two high-tech Swedish manufacturing firms which have a large focus on innovation are the main limitations of this study, as these medium-sized firms have gained some experience to face the specific challenges of FFE of NPD and the data they provide may be influenced by this aspect.</p>