Off-grid hybrid renewable energy systems are known as an attractive and sustainable solution for supplying clean electricity to autonomous consumers. Typically, this applies to the communities that are located in remote or islanded areas where it is not cost-effective to extend the grid facilities to these regions. In addition, the use of diesel generators for electricity supply in these remote locations are proven to be uneconomical due to the difficult terrain which translates into high fuel transportation costs. The use of renewable energy sources, coupling with the diesel generator allows for the diesel fuel to be offset. However, to date, a common design standard for the off-grid system has yet to be found and some challenges still exist while attempting to design a reliable system. These include the sizing of hybrid systems, coordination between the operation of dissimilar power generators and the fluctuating load demands, optimal utilisation of the renewable energy resources and identifying the underlying principles which reduce the reliability of the off-grid systems. In order to address these challenges, this research has first endeavoured into developing a sizing algorithm which particularly seeks the optimal size of the batteries and the diesel generator usage. The batteries and diesel generator function in filling the gap between the power generated from the renewable energy resources and the load demand. Thus, the load requirement is also an important factor in determining the cost-effectiveness of the overall system in the long run. A sensitivity analysis is carried out to provide a better understanding of the relationship between the assessed renewable energy resources, the load demand, the storage capacity and the diesel generator fuel usage. The thesis also presents the modelling, simulation and experimental work on the proposed hybrid wind-diesel-battery system. These are being implemented with a full-scale system and they are based on the off-the-shelf components. A novel algorithm to optimise the operation of a diesel generator is also proposed. The steady-state and dynamic analysis of the proposed system are presented, from both simulation and an experimental perspective. Three single-phase grid-forming inverters and a fixed speed wind turbine are used as a platform for case studies. The grid-forming inverters adopt droop control method which allows parallel operation of several grid-forming sources. Droop control-based inverters are known as independent and autonomous due to the elimination of intercommunication links among distributed converters. Moreover, the adopted fixed speed wind turbine employs a squirrel cage induction generator which is well known for its robustness, high reliability, simple operation and low maintenance. The results show a good correlation between the modelling, the experimental measurements, and the field tested results. The final stage of this research explores the effect of tower shadow on off-grid systems. Common tower designs for small wind turbine applications, which are the tubular and the lattice configurations, are considered in this work. They generate dissimilar tower shadow profiles due to the difference in structure. In this research, they are analytically modelled for a wind turbine which is being constructed as a downwind configuration. It is proven that tower shadow indeed brings negative consequence to the system, particularly its influence on battery lifetime within an off-grid system. This detrimental effect occurs when power generation closely matches the load demand. In this situation, small frequent charging and discharging cycles or the so called microcycles, take place. The battery lifetime reduction due to these microcycles has been quantified and it is proven that they are not negligible and should be taken into consideration while designing an off-grid hybrid system.

FLIM is branch of microscopy mainly used in biology which is quickly improving thanks to a rapid enhancement of instrumentation and techniques enabled by new sensors. In FLIM, the most precise method of measuring fluorescent decays is called TCSPC. High voltage PMT detection devices together with costly and bulky optical setups which scan the sample are usually required in TCSPC instrumentation. SPADs have enabled a big improvement in TCSPC measurement setup, providing a CMOS compatible device which can be designed in wide arrays format. However, sensors providing in-pixel TCSPC do not scale in size and in large array like the time-gated SPAD pixel sensors do. Time-gated pixels offer a less precise lifetime estimation, discarding any photon information outside a given time window, but this loss in photon-efficiency is offset by gains in pixel size. This work is aimed at the development of a wide field TCSPC sensor with a pixel size and fill factor able to reduce the cost of such devices and to obtain a high resolution time-resolved fluorescence image in the shortest time possible. The study focuses on SPAD and pixel design required to maximise the fill factor in sub 10 μm pixel pitch. Multiple pixel designs are proposed in order to reduce pixel area and so enable affordable wide array TCSPC systems. The first proposed pixel performs the CMM lifetime estimation in order to reduce the frame rate needed to stream the data out of the SPAD array. This pixel is designed in a 10 μm pitch and attains with the most aggressive design a fill factor of 10:17 %. A second design proposes an analogue TCSPC which consists in a S/H TAC circuitry. This simpler pixel can achieve a higher fill factor of 19:63% as well as smaller pitch of 8 μm thanks to the adoption of SPAD n-well and electronics area sharing. This last design is implemented in a 320 x 256 SPAD array in which is included part of a novel ADC aimed at reduction of the processing time required to build a TCSPC histogram. A more conventional analogue readout is used to evaluate the pixel performance as well as a more fine TCSPC histogram. The device was used to measure the fluorescence lifetime of green micro-spheres while the 2b flash ADC is used to demonstrate rapid resolution and separation of two different fluorescence decays.

The emerging field of spintronics relies on the manipulation of electron spin in order to use it in spin-based electronics. Such a paradigm change has to tackle several challenges including finding materials with sufficiently long spin lifetimes and materials which are efficient in generating pure spin currents. This thesis predicts that two types of material families could be a solution to the aforementioned challenges: complex oxides and bismuth based materials. We derived a general approach for constructing an effective spin-orbit Hamiltonian which is applicable to all nonmagnetic materials. This formalism is useful for calculating spin-dependent properties near an arbitrary point in momentum space. We also verified this formalism through comparisons with other approaches for III-V semiconductors, and its general applicability is illustrated by deriving the spin-orbit interaction and predicting spin lifetimes for strained SrTiO3 and a two-dimensional electron gas in SrTiO3 (such as at the LaAIO3/SrTiO3 interface). Our results suggest robust spin coherence and spin transport properties in SrTiO3 related materials even at room temperature. In the second part of the study we calculated intrinsic spin Hall conductivities for bismuth-antimony Bi1-xSbx semimetals with strong spin-orbit couplings, from the Kubo formula and using Berry curvatures evaluated throughout the Brillouin zone from a tight-binding Hamiltonian. Nearly crossing bands with strong spin-orbit interaction generate giant spin Hall conductivities in these materials, ranging from 474 ((ћ/e)Ω-1cm-1) for bismuth to 96((ћ/e)Ω-1cm-1) for antimony; the value for bismuth is more than twice that of platinum. The large spin Hall conductivities persist for alloy compositions corresponding to a three-dimensional topological insulator state, such as Bi0.83Sb0.17. The spin Hall conductivity could be changed by a factor of 5 for doped Bi, or for Bi0.83Sb0.17, by changing the chemical potential by 0.5 eV, suggesting the potential for doping or voltage tuned spin Hall current. We have also calculated intrinsic spin Hall conductivities of Bi2Se3 and Bi2Te3 topological insulators from an effective tight-binding Hamiltonian including two nearest-neighbor interactions. We showed that both materials exhibit giant spin Hall conductivities calculated from the Kubo formula in linear response theory and the clean static limit. We conclude that bismuth-antimony alloys and bismuth chalcogenides are primary candidates for efficiently generating spin currents through the spin Hall effect.

Depuis ces deux dernières décennies, une nouvelle technologie sans fil appelée Réseau de Capteur Sans Fil (RCSF) résultant d"une fusion entre les systèmes embarqués et les communications sans fil a vu le jour. Un RCSF ("WSN : Wireless Sensor Network" en Anglais) est un réseau Ad hoc composé d"un grand nombre de nœuds qui sont des micro-capteurs qui peuvent être déployés de façon aléatoire ou déterministe dans une zone d"intérêt donnée. Ces nœuds capteurs sont capables de récolter plusieurs paramètres physiques sur l"environnement qui les entoure, appelé généralement zone de captage (ou zone de surveillance). Ensuite, ils doivent si nécessaire traiter les données capturées et les transmettre à un (ou plusieurs) nœud de collecte appelé station de base, centre de traitement ("sink" en Anglais). Beaucoup de domaines d"applications tels que le contrôle et suivi environnemental, le contrôle de production dans l"industrie, la surveillance de zone, le monitoring de l"habitat, l"agriculture intelligente, etc. sont basés sur les RCSF. Toutefois, les RCSF ne sont pas parfaits. En effet, compte tenu de leur petite taille, leur faible coût et leurs déploiement dans des zones souvent hostiles ou difficiles d"accès, les nœuds capteurs présentent un certain nombre de faiblesses parmi lesquelles une durée de vie du réseau limitée, une bande passante faible, des capacités de capture et de communication réduites, etc. Afin de surmonter ces contraintes des RCSF, plusieurs problématiques de recherche sont nées ces dernières années, et les principales portent sur l"optimisation de la consommation énergétique en vue d"améliorer la durée de vie du réseau. D"autres recherches importantes menées dans le domaine de ces réseaux portent sur les stratégies de placement des nœuds, sur la couverture de zones et sur la connectivité du réseau. Cependant, la plupart des solutions proposées ces dernières années ne prennent pas en compte toutes ces problématiques dans leurs modèles de résolution ; alors que dans beaucoup d"applications des RCSF telles que la surveillance de zone critique, le monitoring de l"habitat, l"agriculture intelligente, il est nécessaire de garantir en même temps une couverture complète de la zone de surveillance, une bonne connectivité du réseau, tout en optimisant au mieux la durée de vie de celui-ci. Le but de cette thèse est donc de proposer de nouveaux mécanismes efficaces pour l"optimisation de la durée de vie dans les RCSF, tout en garantissant, à tout moment de cette durée de vie, une couverture totale de la zone de surveillance, ainsi qu"une bonne connectivité du réseau. Pour atteindre nos objectifs, nous avons étudié et fait des propositions dans deux axes qui sont le placement des nœuds et les mécanismes d"ordonnancement au niveau de la couche MAC. Pour ces derniers, nous avons mis en place un algorithme appelé DSMAC (Distributed Scheduling Medium Acces Control) qui est basé sur notre méthode de placement des nœuds. Par ailleurs, DSMAC permet de couvrir 100% de la zone de surveillance, assure une bonne connectivité du RCSF et permet également aux nœuds capteurs d"économiser jusqu"à 30% de leur énergie comparativement à d"autres protocoles MAC tels que TunableMAC. / Since the past two decades, a new technology called Wireless Sensor Network (WSN) which result in a fusion of embedded systems and wireless communications has emerged. A WSN is Ad hoc network composed of many sensors nodes communicating via wireless links and which can be deployed randomly or deterministically over a given interest region. Theses sensors can also collect data from the environment, do local processing and transmit the data to a sink node or Base Station (BS) via multipath routing. Thereby, a wide range of potential applications have been envisioned using WSN such as environmental conditions monitoring, wildlife habitat monitoring, industrial diagnostic, agricultural, improve health care, etc. Nevertheless,WSN are not perfect. Indeed, given their small size, their low cost and their deployment generally in hostile or difficult access areas, sensor nodes have some weaknesses such as: a limited energy, so a network lifetime limited, limited bandwidth, limited computations and communications capabilities, etc. To overcome these limitations, several research issues from were created in recent years, and the main issues focus on the optimization of energy consumption in order to improve the network lifetime. Other important researches focus on issues of coverage areas, placement strategies of sensor nodes and network connectivity. However, most solutions proposed in recent years to resolve these issues do not take into account all these issues that we cited above in resolutions models; while in many WSN applications such as monitoring critical region, wildlife habitat monitoring, agricultural application, a full coverage of the monitoring region and network connectivity are mandatory as well an energy-awareness network lifetime. The objective of this thesis is thus to propose new scheduling mechanisms for optimizing the network lifetime in WSN, while ensuring at any time of the network lifetime a full coverage of the monitored region and network connectivity. To achieve our goals, we have study and done proposal in two axes which are placement strategy of sensor nodes and scheduling mechanism in the MAC layer. For these, we have implemented a Distributed Scheduling Medium Access Control algorithm (DSMAC) based on our placement method. Furthermore, DSMAC enables to cover 100% of the monitored region, to ensure optimal network connectivity and also allows sensors node to save up to 30% of their energy compared to other MAC protocols such as TunableMAC.

Large-scale wireless sensor networks consist of thousands of tiny and low cost nodes with very limited energy, computing power and communication capabilities. They have a myriad of possible applications. They can be used in hazardous and hostile environments to sense for deadly gases and high temperatures, in personal area networks to monitor vital signs, in military and civilian environments for intrusion detection and tracking, emergency operations, etc. In large scale wireless sensor networks the protocols need to be scalable and energy-efficient. Further, new strategies are needed to address the well-known energy depletion problem that nodes close to the sink node face. In this thesis the Scalable Energy-efficient Location-Aided Routing (SELAR) protocol for wireless sensor networks is proposed to solve the above mentioned problems. In SELAR, nodes use location and energy information of the neighboring nodes to perform the routing function. Further, the sink node is moved during the network operation to increase the network lifetime. By means of simulations, the SELAR protocol is evaluated and compared with two very well-known protocols - LEACH (Low-Energy Adaptive-Clustering Hierarchy) and MTE (Minimum Transmission Energy). The results indicate that in realistic senarios,SELAR delivers up to 12 times more and up to 1.4 times more data packets to the base station than LEACH and MTE respectively. It was also seen from the results that for realistic scenarios, SELAR with moving base station has up to 5 times and up to 27 times more lifetime duration compared to MTE and LEACH respectively.

Ultrafine particles (UFPs) are present in the ambient atmosphere and are generated from atmospheric gases, pollution sources, and combustion. Candles emit carbonaceous soot particles similar to UFPs present in the ambient atmosphere. With the exception of lead, airborne concentrations of candle emissions have not been shown capable of causing cancer or cardiopulmonary disease during normal use. The purpose of this research is to determine the occupational risk associated with candle emissions. Candle studies employ chambers to measure candle emission exposures and assess public health risk. Chambers used in previous studies did not match normal room conditions. They were affected by turbulence and high temperature, which affected particle distribution and constituent concentrations, while making it difficult to extrapolate the results. The chamber designed for this study sought to avoid the problems noted above. This study also employed a room constructed to closely simulate a normal work environment. Candle suppliers and users were surveyed to determine occupational candle use and settings. Scented, unscented, and church candles were measured in both ventilated and unventilated environments. A condensation nuclei counter was used to measure UFPs from candle emissions. Relative to previous chamber designs, results indicated a reduction in candle soot generation, no significant airborne concentrations of metals, and airborne concentrations of polycyclic aromatic hydrocarbons (PAHs), below occupational limits. Scented candles generated more soot than unscented candles. UFP studies have demonstrated only weak associations between ambient UFP exposures and cardiopulmonary disease. However, ambient UFP exposures were used as a benchmark for candle soot exposures. The lifetime average daily dose (LADD) was calculated from the candle soot measurement data and ambient UFP data. Candle soot generated inside the test room ranged from 5.73 x 109 to 1.86 x 1011 number of candle soot particles inhaled daily compared to the 3.25 x1011 to 2.45 x 1012 soot particles inhaled in the ambient environment. The calculated candle soot dose was nearly an order of magnitude less than the calculated ambient dose. The conclusion is that candle emissions do not pose a health risk under normal occupational use.

<p>Varje dag använder sig miljontals svenskar av någon form av medlems- eller kundklubbskort när de handlar i butik, kontaktar en kundtjäst eller loggar in på ett företags hemsida. Motiven till detta kan förstås vara olika - det kan vara smidigt, lönsamt eller nödvändigt för att överhuvudtaget få den hjälp och service man önskar. För företagen är denna registrering å andra sidan ett effektivt sätt att samla information om sina kunder som ett led i deras lojalitetsskapande arbete mot kund. Tidigare, internationella studier av CRM visar dock på att företagen inte utnyttjar den information de har om kunder för att verkligen styra verksamheten.</p><p>Syftet med denna uppsats är att studera om detta är ett aktuellt problem även bland svenska företag genom en enkätundersökning riktad till CRM- och kundklubbsansvariga vid svenska företag. Denna undersökning har utarbetats utifrån Cuthbertsons tre kriterier för att avgöra om en organisation är kundorienterade eller ej.</p><p>Resultat visar att de flesta företag som deltog i studien inte använder informationen man samlar in från kunderna i någon större utsträckning. Däremot visar resulataten att företag med äldre kundklubbar samt med höga medlemsantal generellt är bättre på att sprida och använda den kunskap som kundklubben samlar in. Skälen till att kundinformation inte används i större utsträckning beror enligt vår analys på frånvaron av fungerande intern infrastrauktur för att sprida inhämtad kunddata, kundklubben har för få medlemmar och låg ålder vilket påverkar dess interna status samt att kundklubben främst betraktas som ett register för riktad marknadsföring snarare än som ett redskap för att styra företagens verksamhet i stort.</p>

<p>This study aim at investigating whether income inequality ceteris paribus is a determinant of population health measured by infant mortality rate and average expected lifetime. Earlier research has found results pointing in different directions but the income inequality hypothesis suggests that income inequality alone is something bad for the population. The study uses data on income distribution from the Luxembourg Income Study (LIS) and the World Income Inequality Database (WIID). Data on economic development and health indicators comes from the OECD database. An econometric model which applies country fixed effects is specified and the results indicates no effect from income inequality on infant mortality rate but some indications of a negative effect on average expected lifetime.</p>

The paper sheds some light on the education returns in Germany in the post war period. After describing higher education in Germany the current stand of higher education financing within the single states is presented. In six states tuition fees will be introduced in 2007/08 and discussions are going on in even some more. In the second part of the paper an empirical analysis is done using longitudinal data from the German social pension system. The analysis over the whole lifecycle renders results which proof that the higher education advantages are quite remarkable and might be a justification for more intensified financing by tuition fees. But all this has to be embedded into an encompassing strategy of tax and social policy, especially to prevent a strengthened process of social selection, which would be counterproductive for an increased and highly qualified human capital in Germany.

Der vorgestellte Beitrag gibt einen Überblick über die gegenwärtige Hochschulfinanzierung in Deutschland; kürzlich haben einige Bundesländer Studiengebühren eingeführt, die zu einer teilweisen Finanzierung der Studienkosten beitragen sollen. Im II. Kapitel werden außerdem kurz die finanziellen Strukturen der tertiären Ausbildung in den OECD-Ländern beschrieben. Dabei geht es vor allem um die Kostenaufteilung zwischen öffentlichem und privatem Sektor. Im III. Kapitel werden dann die Verteilungswirkungen des gegenwärtigen Finanzierungssystems kritisch hinterfragt. Dabei wird auch auf den Lebenseinkommensvorteil einer Hochschulausbildung im Detail eingegangen, bevor dann mögliche Auswirkungen einer Gebührenfinanzierung diskutiert werden. Es wird deutlich hervor gehoben, dass die Einführung von Studiengebühren in eine umfassende hochschul- und bildungspolitische Strategie eingebettet sein muss, damit eine negative Selektionswirkung auf die Jugendlichen aus Haushalten mit prekären Einkommen vermieden wird. / The paper sheds some light on the financial structures of higher education in Germany. Recently in several member states of Germany tuition fees have been introduced. Chapter II describes the current situation in Germany, the financial structures in the OECD countries and sheds some light on the higher education costs as well as parts to be borne by the public and private sector. Chapter III discussed the distributional impacts of the current German system and adds some information on the education returns in Germany in the post war period. The analysis over the whole lifecycle renders results which proof that the higher education advantages are quite remarkable and might be a justification for more intensified financing by tuition fees. But all this has to be embedded into an encompassing strategy of tax and social policy, especially to prevent a strengthened process of social selection, which would be counterproductive for an increased and highly qualified human capital in Germany.