The focus of the research is on the development of the concept of floating flexible thin film arrays for renewable electricity generation, in marine and lacustrine application areas. This research was motivated by reliability issues from wave energy converters which are prone to large loads due to the environment which they are exposed in; a flexible system would not need to withstand these loads but simply yield to them. The solid state power take off is an advantage of photovoltaic (PV) technology which removes failure risks associated with mechanical machinery, and also potential environmental hazards such as hydraulic oil spillage. The novelty of this technology requires some development before it could even be considered feasible for large scale installation. Techno-economics are a big issue in electricity developments and need to be scoped in order to ensure that they would be cost-competitive in the market and with other technologies. Other more technical issues relate to the change in expected electrical yield due to the modulation of the PV array according to the waves and the electrical performance of the PVs when in wet conditions. Results from numerical modelling of the modulating arrays show that there is not expected variation in electrical yield at central latitudes (slightly positive), although at higher latitudes there could be considerable depreciation. With regards to the electrical performance a notable improvement was measured due to the cooling effect, slight decrease in performance was also estimated due to water absorption (of ~ 1.4%) within the panels. Overall results from both economic and technical analysis show the feasibility of the concept and that it is a possibility for future commercialisation.

A motivação para este trabalho originou-se da atual tendência do Gás Natural Liquefeito (GNL) se tornar uma importante opção para a diversificação da matriz energética brasileira. Atualmente, os terminais de gás natural liquefeito (GNL) são na maioria estruturas onshore, a construção destes terminais é custosa e muitos investimentos são necessários para atender as legislações ambientais e de segurança. Além disso, um acidente em uma destas instalações poderá produzir um grande impacto em áreas adjacentes. Sob esta perspectiva, surge uma nova proposta: uma unidade flutuante de armazenagem e regaseificação de gás natural liquefeito (FSRU - Floating Storage and Regasification Unit), o qual é uma unidade offshore e que pode trabalhar a quilômetros de distância da costa. O objetivo desta pesquisa é desenvolver uma metodologia de análise de Confiabilidade com o uso de Redes Bayesianas (RB) e aplicá-la na análise do sistema de Regaseificação do FSRU. O uso de RB, entre outras vantagens, permite a representação de incertezas no modelo e de dependências condicionais o que não é possível com as técnicas tradicionais, como por exemplo, as árvores de falhas e de eventos. Como resultado do trabalho, além da apresentação da metodologia a ser desenvolvida, serão identificados os pontos críticos do sistema contribuindo para o desenvolvimento de um plano de manutenção que assegure uma boa operabilidade do sistema com níveis razoáveis de dependabilidade. / The motivation for this research is the propensity of the Liquefied Natural Gas (LNG) becomes an important source of energy. Nowadays, LNG Import Terminals are mostly onshore; the construction of these terminals is costly and many adaptations are necessary to abide by environmental and safety laws. Moreover, an accident in one of these plants might produce considerable impact in neighboring areas. Under this perspective, a new option arises: a vessel known as FSRU (Floating Storage and Regasification Unit), which is an offshore unit, that can work miles away from de coast. The goal is to develop a Bayesian Network Reliability Modeling, which will show a preview of FSRUs Regasification System behavior. Using BN is possible to represent uncertain knowledge and local conditional dependencies. The results intend to clarify the critical equipment of the system and might improve the development of an effective maintenance plan, which can provide good operability with reasonable dependability levels.

A motivação para este trabalho originou-se da atual tendência do Gás Natural Liquefeito (GNL) se tornar uma importante opção para a diversificação da matriz energética brasileira. Atualmente, os terminais de gás natural liquefeito (GNL) são na maioria estruturas onshore, a construção destes terminais é custosa e muitos investimentos são necessários para atender as legislações ambientais e de segurança. Além disso, um acidente em uma destas instalações poderá produzir um grande impacto em áreas adjacentes. Sob esta perspectiva, surge uma nova proposta: uma unidade flutuante de armazenagem e regaseificação de gás natural liquefeito (FSRU - Floating Storage and Regasification Unit), o qual é uma unidade offshore e que pode trabalhar a quilômetros de distância da costa. O objetivo desta pesquisa é desenvolver uma metodologia de análise de Confiabilidade com o uso de Redes Bayesianas (RB) e aplicá-la na análise do sistema de Regaseificação do FSRU. O uso de RB, entre outras vantagens, permite a representação de incertezas no modelo e de dependências condicionais o que não é possível com as técnicas tradicionais, como por exemplo, as árvores de falhas e de eventos. Como resultado do trabalho, além da apresentação da metodologia a ser desenvolvida, serão identificados os pontos críticos do sistema contribuindo para o desenvolvimento de um plano de manutenção que assegure uma boa operabilidade do sistema com níveis razoáveis de dependabilidade. / The motivation for this research is the propensity of the Liquefied Natural Gas (LNG) becomes an important source of energy. Nowadays, LNG Import Terminals are mostly onshore; the construction of these terminals is costly and many adaptations are necessary to abide by environmental and safety laws. Moreover, an accident in one of these plants might produce considerable impact in neighboring areas. Under this perspective, a new option arises: a vessel known as FSRU (Floating Storage and Regasification Unit), which is an offshore unit, that can work miles away from de coast. The goal is to develop a Bayesian Network Reliability Modeling, which will show a preview of FSRUs Regasification System behavior. Using BN is possible to represent uncertain knowledge and local conditional dependencies. The results intend to clarify the critical equipment of the system and might improve the development of an effective maintenance plan, which can provide good operability with reasonable dependability levels.

This thesis deals with a proposal of versatile autonomous circuit equivalents of floating and grounded passive elements by means of modern active tectonic blocks, such as current and voltage conveyors of all three generations. Current conveyors range as essential tectonic blocks in a current mode. Concerning signal processing, it encompasses a mixed tectonic block. In most cases, these elements may be substituted for presently insufficient operating amplifiers. The voltage conveyor was defined on the basis of duality of current and voltage modes. This element could be selected as a suitable active component for circuits operating in a voltage mode. Implementing the connection, a general autonomous circuit is taken into account. By selecting given admittances, a FDNR (floating frequency dependent negative resistance) element, floating capacitance, floating inductance and ground to floating admittance converter may be implemented. The practical part describes connections which fulfill given requirements. The suggested elements are simulated in comparison with ideal elements and subsequently, they are applied to a frequency filter. The second order filter with a proposed induction coil was practically assembled and experimentally measured in a laboratory. The measured results were compared to simulations received by the use of ideal and real models of current and voltage conveyors.

In den letzten Jahren hat die Verbreitung von stationsungebundenem Carsharing (Free- Floating-Carsharing) weltweit stark zugenommen. Aufgrund dessen wurden verschiedene Studien, welche die verkehrliche Wirkung von Free-Floating-Carsharing beschreiben, erstellt. Bisher unzureichend unter-sucht wurden jedoch die Nutzer von Free-Floating-Carsharing- Systemen. Im Rahmen der Mitarbeit der TU Dresden am Evaluationsbericht Carsharing in der Landeshauptstadt München standen für sämtliche Münchener Carsharinganbieter Daten zu Buchungen und Kunden zur Verfügung. Ziel dieser Arbeit war es nun, für die zwei Anbieter von Free-Floating-Carsharing eine Typisierung der Nutzer vorzunehmen. Für die Einteilung der Nutzer in Gruppen wurden zunächst Input-Variablen ausgewählt und erzeugt. Neben den zeitlichen Häufigkeiten der Nutzung für Monate, Wochentage und Zeitscheiben wurden zudem Gini-Faktoren berechnet, welche die Regelmäßigkeit der Nutzung abbilden. Außerdem wurden verschiedene Variablen aus den Buchungsdaten erzeugt. Dazu zählen Untersuchungen wie viele Fahrten amWohnort der Nutzer beginnen und/oder enden, ob Fahrten am gleichen Ort beginnen und enden und bei wie vielen Fahrten der Parktarif der Anbieter zum Einsatz kommt. Des Weiteren wurde untersucht, wie viele Fahrten den Flughafen als Start oder Ziel haben, wie der Einfluss des Wetters auf die Anzahl der Buchungen ist und wie hoch die mittlere Fahrtzeit pro Buchung je Nutzer ist. Alle Variablen dienten nun als Input für die Typisierung der Nutzer. Für die Typisierung wurde das Verfahren der Clusteranalyse ausgewählt. Dabei sind jedoch 30 Variablen eine zu große Anzahl, weswegen zuerst eine Verdichtung der Input-Variablen durchgeführt wurde. Dabei kam eine sogenannte Hauptkomponentenanalyse zum Einsatz. Diese bietet die Möglichkeit, verschieden stark korrelierende Variablen zusammenzufassen und dabei den Informationsgehalt dieser zu erhalten. Aus den 30 einfließenden Variablen ergaben sich mit Hilfe der Hauptkomponentenanalyse vier Faktoren, welche anschließend für die Clusteranalyse genutzt wurden. Jeder Nutzer lässt sich durch die vier Faktoren in einem vierdimensionalen Koordinatensystem ein-tragen. Anschließend kann in diesem Raum eine Clusterung durchgeführt werden. Für diese Arbeit wurde sich für das k-Means-Verfahren entschieden. Mit diesem wurden fünf Cluster bestimmt, welche die 13 000 Nutzer abbilden. Jeder Cluster lässt sich durch die Mittelwerte der eingeflossenen sowie durch soziodemografische Variablen wie Alter und Geschlecht und die Wohnorte der Nutzer hinsichtlich seiner Aussage interpretieren. Die fünf Cluster können in zwei Cluster mit einer niedrigen (Nr. 1 und 2), einen mit einer mittleren (Nr. 3) und zwei mit einer hohen Nutzungsintensität einteilen werden (Nr. 4 und 5). Cluster 1 vereint Nutzer, die selten aber spontane Fahrten unternehmen. Dabei sind überdurchschnittliche viele Fahrten am Wochenende und abends zu verzeichnen. In Cluster 2 finden sich Nutzer, die vorwiegend Fahrten mit langen Fahrtzeiten unternehmen. Dabei werden innerhalb einer Buchung mehrere Wege zurückgelegt, was sich an der hohen Nutzung des Parktarifs zeigt und daran, dass der größte Teil der Fahrten am Ausgangsort wieder enden. Diese Gruppe besitzt unter allen Gruppen einen überdurchschnittlich hohen Anteil an Frauen. Cluster 3 beschreibt den normalen Nutzer hinsichtlich der Nutzungsintensität und der zeitlichen Nutzung. Er ist mit 41,4% der Kunden der größte aller Cluster. Cluster 4 und 5 vereinen Kunden mit einer hohen Nutzungsintensität. Obwohl nur ca. 5% der Kunden in diesen beiden Gruppen zu finden sind, werden jedoch ein Drittel aller Fahrten von diesen Nutzern zurückgelegt. Cluster 4 beschreibt Nutzer mit einem typischen Pendlerverhalten. Dabei werden Fahrten vorwiegend Werktags und während der Hauptverkehrszeiten unternommen. Eine abnehmende Nutzung von Januar zu Juni lässt vermuten, dass andere Verkehrsmittel wie das Fahrrad genutzt werden. In Cluster 5 finden sich Kunden, die häufig Carsharing in der Nacht nutzen. Dies lässt vermuten, dass Aktivitäten des Nachtlebens besucht werden. Dieser Cluster hat im Vergleich zum Durchschnitt den geringsten Anteil an Frauen. Da die Ergebnisse ausschließlich auf den Anbieterdaten basieren, ist es nicht möglich, konkrete Aus-sagen über Effekte und Wirkungen von Free-Floating-Carsharing zu treffen und zu bewerten. Dafür wäre weitere Daten zum Beispiel aus Umfragen notwendig. Die klar abgrenzbaren und gut interpre-tierbaren Nutzergruppen zeigen jedoch, dass die gewählte Methodik sich zur Typisierung von Carsha-ringnutzern eignet. Eine Wiederholung des Verfahrens mit anderen Daten, zum Beispiel aus einem späteren Untersuchungszeitraum oder einer anderen Stadt, ist zu empfehlen.

A new transmission is being designed for a next generation of large, offshore wind turbines, based on floating cup pumps and motors. The machines have a fixed displacement of around five liter per revolution. The objective of this study is to design, manufacture and test the pistons and cups of these machines. To this end, a new test bench has been designed and build, to measure the leakage and friction of the pistons up to a pressure level of 350 bar. Several sets of pistons and cups have been tested against a reference set which was proven to have very little friction at rated and peak operating conditions. The leakage between the pistons and cups was measured at different piston positions at stationary conditions. The friction between the piston and the cup has been measured continuously. From the tests it can be concluded that the friction force is below 0,01% of the piston force. The leakage losses are less than 0,5% of the total effective flow output.

Field Programmable Gate Arrays (FPGAs) are increasingly being used for high-throughput floating-point computation. It is forecasted that by 2009, FPGAs will provide an order of magnitude greater sustained floating-point throughput than conventional processors. FPGA implementations of floating-point operators have historically been designed to use binary floating-point representations, as do general purpose processors. Binary representations were chosen as the standard over three decades ago because they provide maximal numerical accuracy per bit of floating-point data. However, the unique nature of FPGA-based computation makes numerical accuracy per unit of FPGA resources a more important measure of the usefulness of a given floating-point representation. From this viewpoint, higher radix floating-point representations are well suited to FPGA-based computations, especially high precision calculations which require the support of denormalized numbers. This work shows that higher radix representations lead to more efficient use of FPGA resources. For example, a hexadecimal floating-point adder provides a 30% lower Area-Time product than its binary counterpart, and a hexadecimal floating-point multiplier has a 13% lower Area-Time product than its binary counterpart. This savings occurs while still delivering equal worst-case and better average-case numerical accuracy. This work presents a family of higher radix floating-point representations that are designed specifically to interoperate with standard IEEE floating-point, allowing the creation of floating-point datapaths which operate on standard binary floating-point data, yet use higher radix representations internally. Such datapaths provide higher performance by any measure: they are more accurate numerically, consume less FPGA resources and have shorter latencies. When taking into consideration the unique nature of FPGA-based computing systems, this work shows that binary floating-point representations are not optimal for most FPGA-based arithmetic computations. Higher radix representations can therefore be a useful tool for building efficient custom floating-point datapaths on FPGAs.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In a floating medium filter, polymeric beads with a density less than that of water form a floating bed which removes suspended material. Polyolefinic beads (polypropylene and polyethylene) are commonly used as filter media in this application. The geometric properties of the beads, and to a lesser extent the surface properties, strongly influence the performance of the filter. In the case of water treatment, the primary performance requirement is the production of a filtrate with turbidity ≤ 1.0 NTU. The influence of geometric properties on the performance of existing upflow filtration systems has not been extensively researched. The aim of this thesis was therefore to investigate the effects of floating medium granule size and shape on the performance of the floating medium filter (FMF). Towards this goal a pilot plant consisting of a dosing and flocculation unit and a clear PVC column with an inner diameter of 0.3 m and height of 2.8 m was designed and constructed, allowing the effect of media type, bed depth and filtration conditions to be investigated. Artificial feed water for use during the experimental work was made up by dissolving 250 mg/L of bentonite in tap water (≈ 60 NTU). Four median grain sizes (d50 = 2.28, 3.03, 3.30, and 4.07 mm) of polypropylene plastic granules were used. Two media shapes (cubic and disc) were evaluated. The effect of filtration rising velocity, medium depth, and coagulant chemical dosage were investigated using a complete 23 full factorial experimental design. Filter performance was evaluated in terms of filtrate turbidity and headloss development. The direction of filtration was upward in all the experiments. It was found that optimal conditions for turbidity removal were low filtration rate (36.8 L/m2· min), longer media depth (0.6 m) and optimum coagulant dose (23 mg/L). At these conditions the best medium was the one with d50 = 2.28 mm, for which a minimum turbidity of 0.4 NTU was achieved, and which was able to provide 624 L of filtrate of ˂ 1.0 NTU using a bed of 0.014 m3. For this medium headloss was 109 mm H2O at breakthrough, while the other three media showed a headloss of 42 mm H2O at breakthrough. Visual observation indicated that removal of solids took place primarily in the first 0.3 m of the floating bed in the case of the smallest medium, but that solids removal took place over the full depth of the bed for the other three media. It was found that bed depth had the strongest influence on performance for a given medium type. Experimental observation showed that coagulant dosage played an important role in floc size. A higher coagulant dosage (23 mg/L) resulted in a larger floc size which gave better performance. A lower velocity gradient was favourable for the formation of larger flocs. Some effect of media shape was noted, although it appeared that media size was dominant. It is concluded that FMF show promise for application in the water treatment. FMF, however, can be applied successfully as pre-filtration unit for treatment of high turbid water. Proper medium selection in conjunction with operating conditions can enhance performance of the filter. Smaller medium would give better turbidity removal but high headloss development and more frequent backwashing becomes necessary than with larger medium. / AFRIKAANSE OPSOMMING: In ʼn dryfmediumfilter vorm polimeriese korrels met ʼn laer digtheid as dié van water ʼn dryfbedding wat swewende materiaal verwyder. Poli-olefiniese korrels (polipropileen en poliëtileen) word algemeen in hierdie toepassing as filtermedia aangewend. Die geometriese kenmerke, en in ʼn mindere mate die oppervlakkenmerke, van die korrels het ʼn groot invloed op die funksionering van die filter. In geval van waterbehandeling is die hooffunksioneringsvereiste die produksie van ʼn filtraat met ʼn troebelheid van ≤ 1.0 NTU (“nephelometric turbidity units”). Die invloed van die geometriese kenmerke van filtermedia op die funksionering van bestaande stroomop-filtreerstelsels is nog nie omvattend nagevors nie. Die doel van hierdie tesis is dus om ondersoek in te stel na die uitwerking van die korrelgrootte en -vorm van ʼn dryfmedium op die funksionering van die dryfmediumfilter (DMF). Hiervoor is ʼn proefaanleg met ʼn doseer- en uitvlokkingseenheid sowel as ʼn deursigtige pilaar van polivinielchloried (PVC) met ʼn binnedeursnee van 0.3 m en ʼn hoogte van 2.8 m ontwerp en gebou, met behulp waarvan verskillende mediumtipes, beddingdieptes en filtreeromstandighede ondersoek kon word. ʼn Kunsmatige watertoevoer vir die proefneming is vervaardig deur 250 mg/L bentoniet in kraanwater op te los (≈ 60 NTU). Polipropileenplastiekkorrels met vier verskillende deursneë (d50 = 2.28; 3.03; 3.30 en 4.07 mm) is gebruik, en twee mediumvorms (kubus- en skyfvormig) is beoordeel. Die uitwerking van filtrasiestygsnelheid, mediumdiepte en die dosis koaguleermiddel is met behulp van ʼn volledige 23-faktoriaalontwerp ondersoek. Filterfunksionering is aan die hand van filtraattroebelheid en verlies aan drukhoogte beoordeel. Alle proefnemings is teen ʼn opwaartse filtrasierigting uitgevoer. Daar is bevind dat die beste omstandighede vir die verwydering van troebelheid ʼn lae filtrasiekoers (36.8 L/m2 per minuut), ʼn groter mediumdiepte (0.6 m) en ʼn optimale dosis koaguleermiddel (23 mg/L) is. In hierdie omstandighede was die beste medium die een met ʼn d50 van 2.28 mm, waarvoor ʼn minimum troebelheid van 0.4 NTU verkry is, en wat 624 L filtraat van 1.0 NTU met behulp van ʼn bedding van 0.014 m3 kon lewer. By deurbraak het hierdie medium egter ʼn drukhoogteverlies van 109 mm H2O getoon, teenoor die ander drie media se 42 mm H2O op dieselfde punt. Visuele waarneming dui daarop dat, met die kleinste medium, vaste stowwe hoofsaaklik oor die eerste 0.3 m van die dryfbedding verwyder is, teenoor die volle diepte van die bedding vir die ander drie media. Beddingdiepte blyk dus die grootste invloed te hê op funksionering wat enige bepaalde mediumtipe betref. Proefwaarneming toon dat die dosis koaguleermiddel ʼn belangrike rol in vlokgrootte speel. ʼn Hoër dosis koaguleermiddel (23 mg/L) het ʼn groter vlokgrootte en dus beter funksionering tot gevolg. ʼn Laer stygsnelheid blyk ook die beste te wees vir die vorming van groter vlokke. Hoewel mediumvorm oënskynlik ʼn mate van ʼn rol speel, is mediumgrootte eerder die dominante faktor. Volgens die studie blyk DMF belowend vir aanwending in waterbehandeling te wees, veral as voorfiltreereenheid vir die behandeling van baie troebel water. Behoorlike mediumkeuse saam met die regte bedryfsomstandighede kan die funksionering van die filter verder verbeter. Kleiner media sal troebelheid beter verwyder, maar het ʼn groot verlies aan drukhoogte tot gevolg, en sal dus meer gereelde terugspoeling as groter media verg.

Στη παρούσα εργασία παρουσιάζονται τα αποτελέσματα της καταγραφής των επιπλεόντων απορριμμάτων σε δύο θαλάσσιες περιοχές της Δυτικής Ελλάδος: (α) το δυτικό Κορινθιακό κόλπο και (β) το βόρειο τμήμα του Στενού Κέρκυρας Ηγουμενίτσας. Ο δυτικός Κορινθιακός κόλπος χαρακτηρίζεται από ισχυρή συμβολή χερσαίων πηγών ρύπανσης (ποταμοί) ενώ οι ναυσιπλοϊακές γραμμές συνιστούν μια αξιοσημείωτη θαλάσσια πηγή ρύπανσης. Η περιοχή του βόρειου στενού Κέρκυρας-Ηγουμενίτσας ελέγχεται κυρίως από θαλάσσιες πηγές ρύπανσης (ναυσιπλοΐα). Το πλαστικό διαπιστώνεται ότι είναι το κυρίαρχο υλικό και στις δύο περιοχές (83%-82%) ενώ οι γενικές συσκευασίες (23%-21%) και οι συσκευασίες ποτών/αναψυκτικών (32%-22%) οι κυρίαρχες χρήσεις τους. Αναπτύχθηκαν μέθοδοι για τον υπολογισμό και την παρουσίαση της επιφανειακής πυκνότητας των απορριμμάτων και οι μετρήσεις αυτές ερμηνεύτηκαν με βάση τις κυρίαρχες πηγές ρύπανσης. Μέθοδοι στατιστικής ανάλυσης εφαρμόστηκαν για την σύγκριση της σύστασης (υλικό) των επιπλεόντων απορριμμάτων. / In this study, the results of the recording of floating litter in two maritime regions of West Greece are presented: (a) in the west Corinthian gulf and (b) in the north part of the narrow region between Corfu and Igoumenitsa. The west Corinthian gulf is characterized by powerful contribution of overland polluted sources (rivers) while the navigational lines institute one notable maritime source of pollution. The region of the north narrow region between Corfu and Igoumenitsa is controlled mainly from maritime sources of pollution (navigation). It is concluded that the plastic is the predominant material in both regions (83%-82%) while the general packaging (23%-21%) and the beverage packaging (32%-22%) their main uses. Methods have beendeveloped for the calculation and the presentation of the surface density of the litter and these measurements have been interpreted according to the predominant sources of pollution. Methods of statistical analysis have been implemented for the comparison of the consistency (material) of the floating litter.

There is a statistically high probability that within this generation's lifetime, the mean sea level in the south eastern coast of the United States will rise from three to six feet above what it is today. The easiest response to this scenario and its complicated and devastating repercussions is to flee, or to put up a wall. This reaction is defending current lifestyles and cultures against the liabilities and complicated problems associated with sea level rise. This thesis asks: "How can we convert the liabilities of sea level rise into assets?" Using Tybee Island of Chatham County, Georgia as a case study, this thesis will answer this question by exploring 5 topics: 1. Understanding sea level rise 2. Understanding barrier islands of coastal Georgia and Tybee Island 3. The current Sea Level Rise Adaptation Plan for Tybee Island and Where it is Lacking 4. A new urban design strategy in planning for sea level rise on Tybee Island 5. Existing instances of aquatic and amphibious architectures and a new type of amphibious architecture for Tybee Island