This thesis presents the detailed mathematical model developments, operational analysis, and speed field oriented control (FOC) implementation of a Disc-type Surface-mounted Permanent Magnet Synchronous Motor (DSPMSM). According to magnetic circuit concepts, system model was established systematically and simulated by three-dimensional finite element analysis (FEA) in order to verify the analytical model. The operational results and nominal settings were obtained by means of dynamic simulation of DSPMSM. Based on the system model, simulation results, and design specifications, the proposed machine and a DSP-based drive system were implemented. Finally, with application of the designed FOC scheme to regulate the electromagnetic torque production, the objective of rotor speed control was achieved successfully.

En els ecosistemes mediterranis, la recuperació postincendi de les comunitats de plantes i animals és molt variable, depenent tant de factors biòtics com abiòtics. La dinàmica de les poblacions d'animals i plantes ve clarament condicionada per les interaccions que s'estableixen amb altres organismes i són importants en la dinàmica de la recuperació després del foc. Però, són pocs els estudis que analitzen conjuntament la recuperació postpertorbació de les comunitats de plantes i animals. Les interaccions entre les formigues i les plantes són extraordinàriament diverses, i es realitzen en ambdues direccions: les formigues poden actuar sobre les plantes com depredadores o dispersives de llavors, mentre que les plantes poden oferir a les formigues recursos, llocs de nidificació o recobriment. L'objectiu d'aquesta tesi és analitzar l'efecte del foc sobre les comunitats de plantes i formigues mediterrànies i valorar les interaccions entre ambdós grups en l'escenari postincendi. Es demostra com la recuperació postincendi de les comunitats de plantes i formigues de les principals comunitats forestals de Catalunya depèn de la recuperació postincendi de les principals espècies arbòries i/o arbustives, mostrant així un paral·lelisme en la recuperació després del foc d'ambdós grups. També es mostra que la recuperació de les comunitats de plantes i de formigues segueixen un gradient caracteritzat pel dèficit hídric a l'estiu, essent la recuperació superior en àrees més seques que humides. En el cas de la vegetació, una proporció superior de germinadores permet una recuperació més ràpida de la comunitat de plantes pocs anys després del foc; això es deu a les característiques pròpies de les germinadores i a l'escala de temps considerada. La proporció de les diferents estratègies de resposta al foc varia a través del gradient climàtic, augmentant la proporció de germinadores amb la sequera. Per la seva part, les comunitats de formigues de zones més seques es recuperen millor perquè en aquestes zones trobem més espècies característiques d'ambients oberts, els quals són hàbitats similars a aquells generats pel foc. D'altra banda, també es demostra com la vegetació condiciona l'estructura i composició de les comunitats de formigues en els primers anys després del foc a escala més local, de manera que una reducció dels recursos alimentaris i de l'ombra associats a la vegetació per separat produeixen una reducció del número d'espècies de formigues. Les diferents combinacions d'aquests dos factors produeixen un canvi en la composició de la comunitat de formigues. Pocs anys després de la pertorbació, els efectes del foc encara són molt presents, i les comunitats de formigues no segueixen els patrons d'estructuració de comunitats madures. Per altra banda, es demostra com les formigues granívores augmenten les distàncies de dispersió de les espècies de plantes amb curtes distàncies de dispersió abiòtica, i canvien el patró espacial de distribució de les seves llavors. Mitjançant un model demogràfic, es mostra la importància d'aquestes formigues com depredadores, i també, encara que en menor grau, com dispersives.En aquesta tesi es constata clarament l'existència d'interaccions entre les comunitats de plantes i de formigues mediterrànies en un escenari postincendi. Podem afirmar que la recuperació postincendi de les comunitats de plantes condiciona la recuperació de les comunitats de formigues a través de les espècies clau, però en la recuperació de les comunitats de formigues també és important la inèrcia anterior al foc. D'altra banda, i a escala més petita, demostrem que les formigues poden condicionar la dinàmica d'algunes espècies de plantes. Encara que aquest efecte sembla petit, podria ser que amb els anys durant el procés de successió postincendi es vagi acumulant i tingui importants repercussions en la recuperació postincendi d'algunes espècies de plantes, i conseqüentment de les seves comunitats. / In Mediterranean ecosystems, post-fire recovery of plant and animal communities is very variable, depending both on biotic and abiotic factors. Animals and plants population dynamics is conditioned by the interaction with other organisms, which is important for the post-fire recovery dynamics. However, there are few studies that analyse the post-disturbance recovery of animal and plant communities alike. Specifically, plant-ant interactions are extraordinarily diverse, and their implications are two-fold: ants can act on plants like seed predators or dispersers, while plants can offer resources, nesting sites and cover to ants. The aim of my PhD Thesis is to study the impact of fire on Mediterranean plant and ant communities, and to evaluate ant-plant interactions in the post-fire scenario. We show that post-fire recovery of plant and ant communities, in main forest communities of Catalonia, depends on the post-fire recovery of the main tree and/or shrub species. That indicates a strong parallelism between plants and ants regarding their post-fire recovery. Post-fire recovery depends also on the climatic gradient (defined as summer water deficit), the recovery being higher in drier areas. Concerning plants, a higher proportion of obligate seeders allows a quicker recovery of plant communities several years after fire; this is due both to the characteristics of the seeders and to the time scale considered in the study. The proportion of the different functional groups (characterized by their post-fire strategy) varies along the climatic gradient, whereby the proportion of seeders increases with dryness. Concerning ants, communities living on drier areas recover better, because of the higher abundance of species commonly found in open habitats (i.e. habitats similar to those generated by fire). On the other hand, we also demonstrate that the vegetation locally determines the structure and composition of ant communities during the first years after fire. Thus, a reduction either in food resources or in level of shade associated with vegetation causes a decrease in species number. The different combinations of these two factors give rise to changes in the ant community composition. Few years after disturbance, fire effects are still very present, as ant communities do not yet follow the structure pattern of mature communities. On the other hand, we also show that granivorous ants increase the dispersal distance of plant species with short abiotic dispersal distances, and they also change the spatial pattern of their seed distribution. By means of a demographic model we illustrate the importance of ants both as seed predators and, although less importantly, as seed dispersers.In my PhD Thesis, we demonstrate the existence of interactions between Mediterranean ants and plants in a post-fire scenario. We conclude that the post-fire recovery of plant communities in turn determines the post-fire recovery of ant communities through key plant species. Post-fire recovery of ant communities relies also on the inertia before fire. On the other hand, at smaller scale, we demonstrate that ants can modify the dynamics of some plant species. Although this effect is seemingly small, its cumulative effect in the years following the fire may have important consequences for the recovery of some plant species and their communities.

Master of Science / Department of Electrical and Computer Engineering / James E. DeVault / Working with the subject of sensorless motor control requires an understanding of several topical areas; this report presents an understanding that was gained during this research work. The fundamentals of electric motors (particularly brushless motors) are developed from first principles and the basic models are discussed. The theory of sinusoidal synchronous motors is reviewed (phasor analysis of the single phase equivalent circuit). The concept of a complex space vector is introduced and developed using a working knowledge of the sinusoidal synchronous motor. This leads to the presentation of the space vector model of the permanent magnet synchronous motor, in both the stationary and rotor reference frames. An overview of the operation of three-phase voltage source inverters is given, followed by an explanation of space vector modulation and its relationship to regular sinusoidal pulse width modulation. Torque control of the permanent magnet synchronous machine is reviewed in several reference frames and then rotor-flux-field-oriented-control is explained. Finally, some schemes for sensorless operation are discussed.

Los incendios son el tipo de perturbación natural más frecuente en los ecosistemas mediterráneos (Naveh, 1975; Gill et al., 1981; Trabaud, 1981). En un tiempo relativamente corto, y como consecuencia de diferentes factores sociales y climáticos, el efecto de los grandes incendios (mayores de 1000 ha) se ha visto incrementado en los últimos años (Prieto, 1995; Piñol et al., 1998). Así, en el periodo comprendido entre 1987 y 1994 se produjeron en Cataluña (NE Península Iberica) un total de 5279 incendios. El 99.7% de ellos fue menor de 1000 ha y quemó un 30% de la superficie total quemada, mientras que el resto de la superficie se quemó en tan solo 16 incendios de más de 1000 ha (0.3% del total) (Terradas y Piñol, 1996). Los incendios de gran tamaño suelen ser tambien incendios de alta intensidad (Huston, 1994), ya que suelen ir unidos a una cubierta forestal continua y extensa (Huston, 1994; Turner et al., 1994; Piñol et al., 1998), y a determinadas condiciones meteorológicas caracterizadas por largos periodos de sequía y fuertes vientos (Terradas y Piñol, 1996; Turner et al., 1997). Los grandes incendios pueden tener un doble efecto sobre el paisaje. Por un lado, pueden tener un papel homogeneizador, ya que el fuego normalmente arrasa la vegetación independientemente de la densidad, la edad, y la composición específica (Christensen et al., 1989; Bessie y Johnson, 1995), sincronizando en grandes áreas la sucesión de la vegetación (Connell y Slatyer, 1980), y eliminando la heterogeneidad generada por estadios más avanzados de la misma (Huston, 1994). Por otro, los grandes fuegos también pueden tener un efecto heterogenizador que depende de la escala a la que se observan (Turner et al., 1994, 1998): a nivel de paisaje (que correspondería a una escala de 10-104 km2, según McKenzie et al., 1996) se origina un mosaico de áreas quemadas y no quemadas, mientras que a nivel de zona quemada (que correspondería a la escala de bosque/comunidad, es decir, 1-10 km2, según McKenzie et al., 1996), la heterogeneidad espacial es el resultado del mosaico generado por las diferentes severidades con que se quema la vegetación (Turner et al., 1994). Turner et al. (1994) demuestran, en su estudio sobre los efectos del fuego en la heterogeneidad del paisaje del parque nacional de Yellowstone, que el patrón que se crea de áreas quemadas y no quemadas a lo largo del paisaje depende del tamaño del incendio, y que los principales factores que lo controlan son la velocidad y la dirección del viento (Eberhart y Woodward, 1987; Fryer y Johnson, 1988). A una escala espacial más pequeña, las variables ambientales responsables del mosaico de severidades de quema dentro de las zonas quemadas son las variaciones en la cantidad de combustible y de humedad, y la topografía (Christensen et al., 1989; Turner et al., 1994; Glitzenstein et al., 1995), mientras que, a una escala aún más pequeña, de individuo, las variaciones en la intensidad de quema frecuentemente originan una alto grado de heterogeneidad espacial en la supervivencia de las plantas (Christensen et al., 1989; Schullery, 1989). La intensidad del fuego posee un efecto predictible sobre el número y el tipo de plantas que mueren o son dañadas. Este riesgo de mortalidad está relacionada con el tamaño de las plantas (disminuye cuanto mayor es el individuo; Huston, 1994; Johnson, 1992), y con los mecanismos de resistencia al fuego, la inflamabilidad y las estrategias regenerativas de las especies (McKenzie et al., 1996).Entender las causas de la creación de heterogeneidad espacial postincendio, la distribución de áreas quemadas y no quemadas, el patrón de las diferentes severidades de quema y el patrón de supervivencia de las plantas, es básico para comprender la dinámica de la regeneración postincendio de las especies de las áreas quemadas (Turner, 1998). En el presente estudio se examinan, a diferentes escalas, las consecuencias de un gran incendio ocurrido en el nordeste de España en 1994. En concreto, el objetivo principal del estudio es (1) relacionar la heterogeneidad espacial generada por el comportamiento del fuego con las variaciones topográficas y la composición de la vegetación antes del incendio, y (2) ver los efectos directos, los patrones de supervivencia, que produce sobre las principales especies arbóreas (Pinus halepensis Mill.y Quercus ilex L.). / Forest fires are the most frequent type of natural disturbance in Mediterranean-type ecosystems (Naveh 1975; Gill et al. 1981; Trabaud 1991). As a consequence of different climatic and social factors, the effect of large wildfires (i.e., fires larger than ca. 1000 ha) has increased in the last years (Greenpeace, 1995; Piñol et al., 1998). Thus, 99.7% of the 5279 wildfires that burned in Catalonia (NE Iberian Peninsula) between 1987 and 1994, were smaller than 1000 ha, but only affected 30% of the total surface. The remainder 16 wildfires (0.3% of the total) were large wildfires which burned 70% of the total surface (Terradas et al., 1996).wildfires are fires of high intensity (Huston, 1994), because they are associated with a continuous and extensive forest cover (Huston, 1994; Turner et al., 1994; Piñol et al., 1998), and environmental conditions characterized by large drought periods and strong winds (Terradas and Piñol, 1996; Turner et al., 1997). These large wildfires may have a double effect on the landscape. On the one hand, large fires are so extensive and so severe in some areas that they destroy forest vegetation independently of its density, age and composition (Christensen et al., 1989; Bessie and Johnson, 1995). The result is that the burned lanscape appears more homogeneous than it has been before the fire, because the heterogeneous vegetation patterns generated by the different succesion pathways are syncronized in large areas (Connell and Slatyer, 1980; Huston, 1994). On the other hand, large fires often result in a heterogeneous mosaic of burn severities as well of islands of unburned vegetation across the landscape (Turner et al., 1994, 1997). In their study on the effects of large fires on landscape heterogeneity in Yellowstone National Park, Turner et al. (1994) show that this pattern depends on fire size. The main factors responsible of this pattern are wind velocity and direction (Eberhart and Woodward, 1987; Fryer and Johnson, 1988). At a smaller spatial scale, several controlling environmental variables, such as air moisture, fuel type and topography, determine the mosaic of fire severities within the burned area (Christensen et al., 1989; Turner et al., 1994; Glitzenstein et al., 1995). At an even smaller scale, that of individual, fire intensity affects the number and characteristics of plants that are partially or totally burnt, and frequently originates a high degree of spatial heterogeneity in plant survival (Christensen et al., 1989; Schullery, 1989). This mortality risk decreases with plant size (Huston, 1994; Johnson, 1992), and depends on fire-resistance mechanisms, inflamability and regenerative strategies of species (McKenzie et al., 1996).Postfire spatial heterogeneity, which is determined by the distribution of burned and unburned areas and by the patterns of fire severity and plant survival, is basic to understand postfire regeneration in the burned areas (Turner, 1998). In this paper, we examine the characteristics and consequences on vegetation of a large wildfire that occurred in Catalonia (NE Spain) in 1994. The main objectives of this study are (1) to relate the spacial heterogeneity generated by fire behaviour with topography and prefire vegetation composition, and (2) to analyze the main survival patterns shown by the dominant tree species of the area, Aleppo pine (Pinus halepensis Mill.) and holm oak (Quercus ilex L.).

<p>This thesis describes how an algorithm is transferred from a digital signal processor to an embedded microprocessor in an FPGA using C to hardware program from Altera.</p><p>Saab Avitronics develops the secondary high lift control system for the Boeing 787 aircraft. The high lift system consists of electric motors controlling the trailing edge wing flaps and the leading edge wing slats. The high lift motors manage to control the Boeing 787 aircraft with full power even if half of each motor’s stators are damaged. The motor is a PMDC brushless motor which is controlled by an advanced algorithm. The algorithm needs to be calculated by a fast special digital signal processor.</p><p>In this thesis I have tested if the algorithm can be transferred to an FPGA and still manage the time and safety demands. This was done by transferring an already working algorithm from the digital signal processor to an FPGA. The idea was to put the algorithm in an embedded NIOS II microprocessor and speed up the bottlenecks with Altera’s C to hardware program.</p><p>The study shows that the C-code needs to be optimized for C to hardware to manage the up speeding part, as the tests showed that the calculation time for the algorithm actually became longer with C to hardware. This thesis also shows that it is highly probable to use an FPGA equipped with Altera’s NIOS II safety critical microprocessor instead of a digital signal processor to control the electrical high lift motors in the Boeing 787 aircraft.</p>

This thesis describes how an algorithm is transferred from a digital signal processor to an embedded microprocessor in an FPGA using C to hardware program from Altera. Saab Avitronics develops the secondary high lift control system for the Boeing 787 aircraft. The high lift system consists of electric motors controlling the trailing edge wing flaps and the leading edge wing slats. The high lift motors manage to control the Boeing 787 aircraft with full power even if half of each motor’s stators are damaged. The motor is a PMDC brushless motor which is controlled by an advanced algorithm. The algorithm needs to be calculated by a fast special digital signal processor. In this thesis I have tested if the algorithm can be transferred to an FPGA and still manage the time and safety demands. This was done by transferring an already working algorithm from the digital signal processor to an FPGA. The idea was to put the algorithm in an embedded NIOS II microprocessor and speed up the bottlenecks with Altera’s C to hardware program. The study shows that the C-code needs to be optimized for C to hardware to manage the up speeding part, as the tests showed that the calculation time for the algorithm actually became longer with C to hardware. This thesis also shows that it is highly probable to use an FPGA equipped with Altera’s NIOS II safety critical microprocessor instead of a digital signal processor to control the electrical high lift motors in the Boeing 787 aircraft.

Electrical drive systems are used in various applications and getting more attractive in recent years. When the usage of electric motors increased in different applications then the control model of them has been also demanded. This work is aimed at deeper research to gain a better understanding of three different control models for electric motors, in case of this work a brushless direct current (BLDC) motor. Three different types of control models (6-step, sinusoidal and FOC control) have been investigated and designed using MATLAB/SIMULINK. Then the control models have been implemented in an Arduino Due based BLDC motor and its functionality has been configured. The results show that the FOC control model provided to work better in the simulation while the implementation of the hardware showed that sinusoidal control works a little better and smoother. Making the implementation of the control models to the hardware work better requires more works and this has been left for future work.

Práce se zabývá modelováním PMSM, jeho parametry a jejich získáváním. Dále je v práci popsán model měniče beroucí v potaz dead-time efekt. Tyto modely jsou implementovány společně s dalšími bloky v prostředí Matlab/Simulink a dohromady tvoří knihovnu pro vektorové řízení motorů FSL_MC_TOOL. Součástí práce je také měření a identifikace parametrů skutečného PMSM. Dále byly vytvořeny příklady simulací, v nichž je použit motor s těmito parametry a vyhodnocena přesnost simulace. Tímto jsou simulace ověřeny na reálném systému.

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most destructive plant diseases in recorded history. The disease was first discovered in Australia in 1874 but became renowned for the severe losses it caused to export banana plantations during the 1960s in Central America. The banana export industry was saved only by replacing Gros Michel bananas, the dessert banana grown for the export market, with highly resistant Cavendish banana cultivars. Despite this apparent solution, the fungus was found to attack Cavendish bananas in the sub-tropics, where plants were believed to be predisposed to the disease by the cool winter climate. Good management practices and conventional disease management strategies have not been sufficient to reduce losses and stop the disease from spreading, and today Fusarium wilt can be found in almost all banana-producing countries of the world. Since 1988, Foc has been responsible for significant losses of Cavendish bananas in tropical Asia. The only sustainable control measure, the use of resistant varieties, is not always popular as people prefer to eat locally adopted varieties that, unfortunately, are susceptible to Foc. Sustainable Fusarium wilt management in banana depends on the improvement of existing banana cultivars or the development of novel disease management strategies. Molecular biology and biotechnology provide opportunities to introduce foreign resistance genes into existing cultivars and to develop new, environmentally friendly products that can protect susceptible bananas from Foc. Better knowledge of the Fusarium wilt pathogen, its diversity, and its mechanisms of pathogenesis will contribute significantly to developing these novel approaches for control of the disease. Molecular information on the pathogenicity of Foc, however, is limited, whereas other formae speciales of F. oxysporum have been better studied. In this thesis, Agrobacterium tumefaciens-mediated transformation of (ATMT) was employed to investigate genes responsible for pathogenicity of Foc to banana. Chapter 1 provides an overview of pathogenicity in F. oxysporum. Pathogenic and non-pathogenic forms of the fungus are first introduced to the reader, and then the biology, epidemiology and etiology of pathogenic forms of F. oxysporum are discussed. The genetic make-up and ability of the Fusarium wilt fungus to cause disease in plants concludes the first part of the review. In recent years, there has been a noted increase in the number of techniques available to study hostpathogen interactions. The second part of the review concentrates on these techniques and their applications in studying pathogenicity of the Fusarium wilt pathogen. In Chapter 2, an ATMT and screening system for Foc was developed. Five A. tumefaciens strains were evaluated for their efficiency to transform Foc with a randomly integrating vector that confers hygromycin B resistance and expression of green fluorescent protein (GFP). A small insertion mutant library of Foc was created, and a subset of transformants was characterized by determining the number of T-DNA inserts present, the location and identity of predicted genes disrupted by T-DNA insertion, and whether transformants of Foc were altered in their virulence against susceptible banana plants. In Chapter 3, the role of a known pathogenicity gene, Frp1, of the tomato pathogen F. oxysporum f. sp. lycopersici (Fol) was investigated in Foc. The first objective was to isolate and characterize the Frp1 gene in Foc, and to compare it to the homologous gene in Fol. A vector containing a modified Fol Frp1 gene was then obtained and used for targeted disruption of the gene in Foc via ATMT. Mutants in which the Frp1 gene was disrupted were then analyzed for GFP expression, culture morphology, and alterations in pathogenicity to banana. / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

There are several benets of electrohydraulic power steering systems, as compared to hydraulicpower steering systems where the pump is driven directly by the engine of the vehicle. Someof these benets are increased eciency and improved steering performance. The purpose ofthis project is to create a simulation model of the electrohydraulic power steering system inSimulink, excluding the hydraulic circuit. The model should thus consist of the electric motor,the drive electronics, the control system, the hydraulic pump as well as the communication andinterface to the master simulation system in which the model will be used.As a start a mathematical model of the motor is derived. Then the motor controller includingtwo current controllers and a speed controller is developed. The switching signals for the threephase bridge that drives the motor are calculated using space vector modulation. The motordrives a hydraulic pump, which is modeled using data sheet eciency curves. Finally a thermalmodel of the drive is developed. To fulll real time requirements, a lumped parameter approachis chosen. The nal model is exported as a Functional Mock-up Unit, which is a black-boxencapsulation of the complete simulation model.The simulation model is compared to measurement data to conrm its validity. Thesecomparisons shows that the dynamic response of the motor and its controller are close to themeasured values and that the thermal model adequately corresponds to the thermal tests. Thehydraulic pump model varied from measurements more than the other sub-modules. It was,however, seen as acceptable. Overall the system response was satisfactory, but naturally a lotof future improvements and new features could be made to improve the model. / Det finns flera fördelar med elektrohydraulisk servostyrning, där hydraulpumpen drivs av en el-motor, jämfört med hydraulisk servostyrning, där pumpen drivs direkt av fordonets förbränningsmotor. Några av dessa fördelar är ökad effektivitet och förbättrad styrprestanda. Syftet med detta projekt är att skapa en Simulink-modell av ett elektrohydraulisk system för servostyrning, exklusive hydraulkretsen. Modellen ska alltså bestå av delmodeller för elmotorn, drivelektroniken, styrsystemet, hydraulpumpen samt kommunikation med den övergripande simuleringsplattformen.Inledningsvis beskrivs en matematisk modell av elmotorn och efter det utvecklas motorstyrningen, bestående av två strömregulatorer samt en hastighetsregulator. Spänningen från strömregulatorerna uppnås genom space vector-modulation, som beräknar de pulskvoter som krävs för att uppnå denna spänning. Elmotorn driver en pump. Denna pump modelleras med hjälp av data från pumpens datablad. Slutligen modelleras drivelektronikens termiska egenskaper med ett termiskt nätverk. Den slutliga modellen omsluts av en Functional Mock-up Unit somintegreras i den övergripande simuleringsplattformen.