The transport sector is seen as particularly problematic when concerns about climate change and dependency on fossil energy are discussed. Because of this, bioenergy is strongly promoted for use in the transport sector, both on a European level and nationally in Sweden. Even though bioenergy is considered one of the key solutions, it is generally agreed that both supply- and demand-side measures will be needed to achieve a change to a more sustainable transport system. One of the reasons for this is the limited availability of biomass, especially agricultural feedstocks competing with food or feed production. Woody biomass, however more abundant, is also exposed to tough competition from other sectors. In this thesis, the role of biogas as a vehicle fuel in a future sustainable transport system is discussed together with the prerequisites needed to realise such a transport system. Biogas is a biofuel that could be produced in several different ways: by anaerobic digestion, which is a first-generation production route, by gasification, which is a second-generation process, and by catalytic reduction of carbon dioxide, a third-generation technology. The main focus in this thesis is on biogas produced by anaerobic digestion and the results show that there is a significant potential for an increase compared to today’s production. Biogas from anaerobic digestion, however, will only be able to cover a minor part of the demand in the Swedish transport sector. Considering biogas of the second and third generations, the potential for production is more uncertain in a mid-term future, mainly due to competition for feedstock, the possibility to produce other fuels by these processes, and the present immaturity of the technology. The limited potential for replacing fossil vehicle fuels, either by biogas or other renewable fuels, clearly shows the need for demand-side measures in the transport system as well. This thesis shows the importance of technical and non-technical means to decrease the demand for transport and to make the transport as efficient as possible. The results show that both energy-efficient vehicles and behavioural and infrastructural changes will be required. Policies and economic incentives set by governments and decision-making bodies have a prominent role to play, in order to bring about a shift to a more sustainable transport system, however, measures taken on individual level will also have a great impact to contribute to a more sustainable transport system. / <p>QC 20121116</p>

The declining cost of photovoltaic (PV) modules has enabled the vision of ubiquitous photovoltaic (PV) power to become feasible. Emerging PV technologies are facilitating the creation of intentionally non-flat PV modules, which create new applications for this sustainable energy generation currently not possible with the traditional rigid, flat silicon-glass modules. However, since the photovoltaic cells are no longer coplanar, there are significant new requirements for the power electronics necessary to convert the native form of electricity into a usable form and ensure maximum energy harvest. Non-uniform insolation from cell-to-cell gives rise to non-uniform current density in the PV material, which limits the ability to create series-connected cells without bypass diode or other ways to shunt current, which is well known in the maximum power tracking literature. This thesis presents a modeling approach to determine and quantify the variations in generation of energy due to intentionally non-flat PV geometries. This will enable the power electronics circuitry to be optimized to harvest maximum energy from PV pixel elements – clusters of PV cells with similar operating characteristics. This thesis systematically compares different geometries with identical two-dimensional projection "footprints" for energy harvest throughout the day. The results show that for the same footprint, a semi-cylindrical surface harvests more energy over a typical day than a flat plate. The modeling approach is then extended to demonstrate that by using non flat geometries for PV panel, the availability of a remotely located stand-alone power system can be increased when compared to a flat panel of same footprint. These results have broad application to a variety of energy scavenging scenarios in which either total energy harvested needs to be maximized or unusual geometries for the PV active surfaces are required, including building-integrated PV. This thesis develops the analysis of the potential energy harvest gain for advanced non-planar PV collectors as a necessary first step towards the design of the power electronics circuits and control algorithms to take advantage of the new opportunities of conformal and non-flat PV collectors.

This study aimed to extend the knowledge on player and surface loading by contributing new data in relation to a greater range of movements, relevant in-game scenarios and on carefully controlled third generation artificial turf surfaces. This was done by selecting soccer relevant movements and in-game scenarios for a player movement study with the help of a player focus group and questionnaire. Furthermore, four surfaces were created with surface hardness and rotational traction values at the upper and lower limits of the standards set by FIFA. The study showed that both the surface hardness and rotational traction properties can affect the human movement dynamics, though these effects were mainly present during the stop and turn manoeuvre. During the stop and turn manoeuvre the soft and high traction surfaces conditions led to increased frontal plane moments as well as increased average ground reaction forces during mid-stance. In combination with decreased ground contact times it appeared that the players were able to decelerate / accelerate faster and generate a larger force on the soft and high traction surfaces. During peak push off it appeared that the players were able to generate a larger force on the hard surfaces, which also led to a significant increase in plantar flexion moment. While some parameters showed an effect for surface hardness and / or rotational traction across all four surface conditions, for others such as the knee valgus, hip extension and hip internal rotation moment showed only a significant effect between two of the four surfaces. At the same time the other surfaces showed either no effect or the opposite effect. This suggests that the effects of the surface hardness can be influenced by the rotational traction properties, and vice versa. Regarding the jumping / heading manoeuvre the effects of the surface conditions were limited. This may have been related to the high demands of the movement, or to limitations of the mechanical measurement methods. In addition to the effects of surface properties on human movement dynamics the study also showed that the mechanical measurement methods may not be representative of the human loading. The impact force conditions of the advanced artificial athlete were substantially different to that of the stop and turn and jumping / heading manoeuvre. Whereas for the rotational traction test the study showed that the rotation of the foot during the ST was substantially less than the minimum 45° required by the FIFA guidelines. Regarding the inclusion of in-game scenarios the study showed that both the simulated opponent used for the stop and turn manoeuvre, and heading a ball during a maximal vertical stop jump manoeuvre can affect the human movement dynamics. During the stop and turn with a simulated opponent the frontal plane moments in the lower limbs were significantly increased. However, this increase in joint loading could not be related to any changes in movement strategy. During the landing after heading a ball during a maximal vertical stop jump the players used a different landing strategy by landing in a more upright position and increasing the ankle plantar flexion ankle just before lading. This allowed for a larger change in the ankle plantar / dorsi flexion angle to absorb the impact of the landing. In addition to this, the heading manoeuvre also led to a significant increase in the frontal plane joint moments of the lower limbs. For future studies it is recommended that a combination of surface properties is used to gain insight into how these affect each other regarding the effects they have on human movement dynamics. In addition, they should provide detailed information on the surface design as well as the properties. Regarding the quantification of the properties it is recommended that in addition to industry standards the surfaces are also quantified using conditions closer to those expected within the study. It is also recommended that future studies incorporate in-game scenarios in order to gain more insight into the effects of interventions that simulate actual match situations.

Thesis (MA (English))--University of Stellenbosch, 2009. / ENGLISH ABTRACT: In recent years, original and exciting developments have been taking place in Nigerian literature. This new body of literature, collectively referred to as the ―third generation‖, has lately received international acclaim. In this emergent literature, the negotiation of a new, contemporary identity has become a central focus. At the same time, recent Nigerian literary texts are articulating responses to various developments in the Nigerian nation: Nigeria‘s current political and socio-economic situation, diverse forms of cultural hybridisation, as well as an increasing trans-national consciousness, to mention only a few. Three 21st-century novels – Chimamanda Nogzi Adichie‘s Purple Hibiscus (2004), Sefi Atta‘s Everything Good Will Come (2004) and Chris Abani‘s GraceLand (2005) – reveal how new avenues of identity-negotiation and formation are being explored in various contemporary Nigerian situations. This study tracks the ways in which the Bildungsroman, the novel of self-development, serves as a vehicle through which this new identity is articulated. Concurrently, this study also grapples with the ways in which the articulation and negotiation of this new identity reshapes the conventions of the classical Bildungsroman genre, thereby establishing a unique and contemporary Nigerian Bildungsroman for the 21st century. The identity that is being negotiated by the third generation is multi-layered and inclusive, as opposed to the exclusive and unitary identities which are observable in Nigerian novels of the previous two generations. Such inclusivity, as well as the hybrid environments in which this identity is being negotiated, results in a form of ―identity layering‖. Thus, the individual comes into being at the point of intersection, overlap and collision of various modes of self-making. Such ―layering‖ allows the individual, albeit not without challenge, to perform a self-styled identity, which does not necessarily conform to the dictates of society. At the same time, the identity is negotiated by means of an engagement, in the form of intertextual dialoguing, with Nigeria‘s preceding literary generations. The most prominent arenas in which this new identity is negotiated include silenced domestic spaces, religo-cultural traditions, constructs of gender and nation, as well as in multicultural and hybrid communities. The investigation conducted in this thesis will, consequently, also focus on such areas of Nigerian life, as they are portrayed in the focal texts. Various theories of literary analysis (some of which specifically focus on Nigeria), Bildungsroman theory, theories of allegory, (imaginative) nation formation, feminism, gender and performativity, as well as theories of cultural identity and cultural exchanges, will form the critical and theoretical framework within which this investigation will be executed. Chapter One explores how Purple Hibiscus‘s protagonist, Kambili Achike, negotiates her gender identity and voice in order to constitute herself as an independent, self-authoring individual. Chapter Two, which focuses on Everything Good Will Come, investigates the dialectic relationship between Enitan Taiwo‘s national and personal identity, which inevitably leads to her quest to reconceive her gender identity, since national identity, as she finds out, is always an engendered construct. In its analysis of GraceLand, Chapter Three turns to the difficulties that Elvis Oke faces when he attempts to negotiate an alternative masculine identity within a rigid patriarchal system and between the cracks of a fraudulent African modernity. / AFRIKAANSE OPSOMMING: In die afgelope paar jaar was daar opwindende, oorspronklike ontwikkelinge in Nigeriese literatuur. Hierdie nuwe literatuurkorpus, wat gesamentlik bekend staan as die ―derde generasie, het onlangs internasionale erkenning ontvang. In hierdie opkomende literatuur, kry die soeke na 'n nuwe, kontemporêre identiteit ‘n sentrale fokus. Terselfdertyd reageer onlangse Nigeriese literêre werke met verskeie ontwikkelinge in die Negeriese nasie: Nigerië se huidige politieke en sosio-ekonomiese situasie, diverse vorme van kultuurverbastering asook 'n toenemende trans-nasionale bewustheid, om maar ‘n paar te noem. Drie 21ste eeuse romans – Chimamanda Nogzi Adichie se Purple Hibiscus (2004), Sefi Atta se Everything Good Will Come (2004) en Chris Abani se GraceLand (2005) – onthul hoe nuwe kanale van identiteidsonderhandeling en –vorming in verskeie kontemporêre Nigeriese situasies ondersoek word. Hierdie studie ondersoek die maniere waarop die Bildungsroman, die roman van selfontwikkeling, as ‗n medium dien waardeur hierdie nuwe identiteit geartikuleer word. Terselfdertyd sal hierdie studie ook worstel met die maniere waarin die artikulasie en soeke na hierdie nuwe identiteit die konvensies van die klassieke Bildungsroman genre hervorm, en daardeur 'n unieke en kontemporêre Nigeriese Bildungsroman vir die 21ste eeu vestig. Die identiteit wat ontwikkel deur die derde generasie is veelvlakkig en inklusief en staan teenoor die eksklusiewe, eenvormige identiteite wat in Nigeriese romans van die vorige twee generasies opgemerk word. Hierdie inklusiwiteit, sowel as die hibriede omgewings waarin hierdie identeite ontwikkel word, lei tot die vorming van identiteitslae. Die individu kom dus tot stand by die kruising, oorvleueling en botsing van verskillende metodes van selfvorming. Hierdie vorming van lae laat die individu toe, alhoewel nie sonder uitdagings nie, om 'n selfgevormde identiteit te hê wat nie noodwndig aan die eise van die gemeenskap voldoen nie. Terselfdertyd word hierdie identiteit onderhandel deur ‗n skakeling met Nigerië se voorafgaande literêre generasies in die vorm van intertekstuele dialoog. Die mees prominente omgewings waar hierdie nuwe identiteit onderhandel word, sluit stilgemaakte huishoudelike spasies, religieus-kulturele tradisies, konstrukte van gender en nasie, sowel as multi-kulturele en hibriede gemeenskappe in. Die ondersoek wat in hierdie tesis uitgevoer sal word, sal daarom ook fokus op hierdie areas van Nigeriese lewe, soos deur die fokale tekste voorgestel. Verskeie teorieë van literêre analise (sommige wat spesifiek op Nigerië fokus), Bildungsromanteorie, teorieë van allegorie, (denkbeeldige) nasievorming, feminisme, gender en performatiwiteit, sowel as teorieë van kultuuridentiteit en -uitruiling, vorm die kritiese en teoretiese raamwerk waarbinne hierdie ondersoek uitgevoer sal word. Hoofstuk een ondersoek hoe Purple Hibiscus se protagonist, Kambili Achike, haar genderidentiteit onderhandel en uitdrukking gee om haarself as onafhanklike, self-skeppende individu te vorm. Hoofstuk twee, wat fokus op Everything Good Will Come, ondersoek die dialektiese verhouding tussen Enitan Taiwo se nasionale en persoonlike identiteit, wat onvermydelik lei tot die herbedenking van haar genderidentiteit, aangesien nasionale identiteit, soos sy uitvind, altyd 'n gekweekte konstruk is. In sy analise van GraceLand, draai Hoofstuk drie om die moeilikhede wat Elvis Oke in die gesig staar wanneer hy probeer om ‘n alternatiewe manlike identiteit te onderhandel in 'n rigiede patriargale sisteem tussen krake van 'n bedrieglike Afrika-moderniteit.

Nowadays, Third Generation (3G) mobile phones equipped with powerful hardware are becoming popular and dominating the market of cellular com-munication systems. Features such as music and video players, in-built Global Positioning System (GPS) receivers, navigation maps, Internet connectivity and high resolution cameras has converted mobile phones into so called Smartphones. With the increase in applications and services, limitations on energy consumption are also increasing. Therefore, it is more im-portant for manufacturers to nd e ective means of increasing battery life of mobile phones, as the mobile device itself is energy consuming and longer operational times are demanded by customers. Good energy mangement in mobile phones requires a good understanding of the energy usage in mobile phones. To this end, this thesis report presents the results of power and energy consumption measurements conducted on available Smartphones. The services under investigation includes basic Smartphone functionalities and few Internet services are studied and conclusions were drawn. This paper presents a cost e ective methodology for reliable measurements of energy on Smartphones. It also examines the e ect of operating systems on en-ergy consumption in mobile phones and reports less energy consumption for Android supported phones. The energy consumption of these Smartphones with respect to various applications has been studied and related to Quality of Experience of users&apos;. Based on the results conclusions were drawn. / This Thesis will serve as a guide to manufacturers and Users of smartphones while choosing smartphones and designing energy-efficient protocols. / +46 (0)723260656

The work deals with the developmental stages (Releases) of the third generation UMTS net-works. It explains a partial improvement from Release 99 to Release 5 and Release 6 to im-prove the quality parameters of a mobile data transmission. In the practical part, there are measured qualitative parameters of the third generation networks that are available in the Czech Republic: UMTS, HSDPA, CDMA 1xEV-DO Rev.0 and Rev.A and UMTS-TDD. The measurements give reasonably achievable data rates in both directions (downlink & uplunk), a response time, quality of VoIP calls, a dispersion, a data-loss and an ability to transmit video with different data flows. The other aspects especially an availability of coverage and end-user terminals have been assessed wihin the each network. The work is supplemeted with a laboratory, which is focused on a practical comparison of the basic parameters of data transmissions of 2G and 3G networks.

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The aim of this thesis is to develop a deeper understanding and the technology in the nascent field of solid-state organic-inorganic perovskite solar cells. In recent years, perovskite materials have emerged as a low-cost, thin-film technology with efficiencies exceeding 16% challenging the quasi-paradigm that high efficiency photovoltaics must come at high costs. This thesis investigates perovskite solar cells in more detail with a focus on incorporating plasmonic nanostructures and perovskite film formation. Chapter 1 motivates the present work further followed by Chapter 2 which offers a brief background for solar cell fabrication and characterisation, perovskites in general, perovskite solar cells in specific, and plasmonics. Chapter 3 presents the field of plasmonics including simulation methods for various core-shell nanostructures such as gold-silica and silver-titania nanoparticles. The following Chapters 4 and 5 analyze plasmonic core-shell metal-dielectric nanoparticles embedded in perovskite solar cells. It is shown that using gold@silica or silver@titania NPs results in enhanced photocurrent and thus increased efficiency. After photoluminescence studies, this effect was attributed to an unexpected phenomenon in solar cells in which a lowered exciton binding energy generates a higher fraction of free charge. Embedding thermally unstable silver NPs required a low-temperature fabrication method which would not melt the Ag NPs. This work offers a new general direction for temperature sensitive elements. In Chapters 6 and 7, perovskite film formation is studied. Chapter 6 shows the existence of a previously unknown crystalline precursor state and an improved surface coverage by introducing a ramped annealing procedure. Based on this, Chapter 7 investigates different perovskite annealing protocols. The main finding was that an additional 130°C flash annealing step changed the film crystallinity dramatically and yielded a higher orientation of the perovskite crystals. The according solar cells showed an increased photocurrent attributed to a decrease in charge carrier recombination at the grain boundaries. Chapter 8 presents on-going work showing noteworthy first results for silica scaffolds, and layered, 2D perovskite structures for application in solar cells.

O crescente aumento da demanda de tráfego nas redes celulares vem aumentando a necessidade de uma melhor utilização dos recursos do sistema, já que sua expansão é custosa. Nas estações rádio base (ERB), a disponibilidade de largura de faixa de freqüências é limitada e desta maneira, em uma rede de comunicação móvel celular, o controle de admissão de chamadas exerce grande influência no desempenho do sistema, pois determina a utilização de banda das ERBs e se uma determinada quantidade de recursos (banda) será alocado ou não para uma determinada chamada. O desempenho da rede pode ser atrelado a determinados parâmetros, como a probabilidade de bloqueio de novas chamadas, probabilidade de bloqueio de chamadas handoff e a utilização de banda da rede. Este trabalho propõe um controle de admissão de chamadas que, no atendimento de uma chamada, faz o empréstimo de banda de chamadas em andamento na célula no caso de banda insuficiente. O sistema adota um mecanismo heurístico que determina a banda disponível para novas chamadas conforme os valores de certos parâmetros do sistema. O empréstimo de banda é realizado em chamadas em andamento nas células até níveis mínimos estabelecidos para cada tipo de chamada, que se diferenciam pelas necessidades de banda de cada uma. O algoritmo foi aplicado às bandas e características de uma rede de terceira geração (3G), que possui chamadas de voz, videoconferência, interação multimídia, e-mail, downloads e transferência de arquivos e a uma rede GSM/GPRS (global system for mobile communications/ general packet radio service), que possui chamadas de voz e de dados. Os resultados mostram melhorias na probabilidade de bloqueio de novas chamadas, probabilidade de bloqueio de handoff e na utilização de banda do sistema. / The recent growth in traffic loads in cellular networks has seen the need for a better use of system resources as its expansion is expensive. In the base transceiver station (BTS), the bandwidth availability is limited. Thus, in cellular networks the call admission control greatly influences the system performance because it determines the bandwidth use of the BTSs and if an amount of resources will or will not be allocated to a call. The network performance can be evaluated by parameters such as blocking probability of new calls, dropping probability of handoff calls and bandwidth use. This work proposes a call admission control that carries out the bandwidth borrowing when a call arrives and there is not enough bandwidth. The system makes use of a heuristic mechanism that determines the available bandwidth for the new calls according to some parameter values of the system. The bandwidth borrowing is applied to the cell ongoing calls until the minimum levels for each type are met. The algorithm was applied to the bandwidths and characteristics of a third generation cellular network, which supports voice calls, videoconference, multimedia interaction, e-mails, downloads and file transfers. It was also applied to a GSM/GPRS (global system for mobile communications/ general packet radio service), which supports voice and data calls. The results show improvements in the blocking probability of new calls, dropping probability of handoff calls and in the bandwidth use of the system.