Στις μέρες μας το ενεργειακό πρόβλημα αποτελεί ένα από τα σπουδαιότερα προβλήματα του πλανήτη, το οποίο μαζί με την ραγδαία κλιματική αλλαγή οδηγούν στην ανάγκη για παραγωγή ηλεκτρικής ενέργειας με όσο πιο οικονομικό αλλά και φιλικό προς το περιβάλλον τρόπο. Συνεπώς οι Ανανεώσιμες Πηγές Ενέργειας και κυρίως η αιολική ενέργεια αποκτούν σπουδαίο ρόλο στο στόχο αυτό και αλλάζουν άρδην τόσο τον Ευρωπαϊκό όσο και τον Παγκόσμιο ενεργειακό χάρτη. Στην παρούσα διπλωματική εργασία μελετάμε μια διάταξη ανεμογεννήτριας, η οποία αποτελείται σε πρώτη φάση από μια επαγωγική μηχανή βραχυκυκλωμένου κλωβού (SCIG), από έναν μετατροπέα συχνότητας (back-to-back converter) και από ένα σε σειρά συνδεδεμένο τριφασικό R-L φίλτρο στην ac πλευρά μέχρι το ζυγό διασύνδεσης με το δίκτυο, ενώ στη συνέχεια προσθέτουμε, μετά το R-L φίλτρο, μια συστοιχία πυκνωτών συνδεδεμένων σε αστέρα, ένα τριφασικό R-L φορτίο στο ίδιο σημείο με τη συστοιχία πυκνωτών καθώς και τη γραμμή μεταφοράς για σύνδεση με το δίκτυο. Σκοπός λοιπόν αυτής της εργασίας είναι να μελετήσουμε το πλήρες σύστημα της ανεμογεννήτριας στο d-q στρεφόμενο σύστημα κάθετων αξόνων μέσω του μετασχηματισμού Park. Στη συνέχεια προχωρούμε στον υπολογισμό των εξισώσεων στο χώρο κατάστασης και τελικά προτείνουμε ένα σύστημα ελέγχου το οποίο βασίζεται στους PI ελεγκτές. Τέλος, προσομοιώνουμε το πλήρες σύστημα με το Simulink του MATLAB και στη συνέχεια παρουσιάζουμε τις αποκρίσεις των προσομοιώσεων και εξάγουμε συμπεράσματα. / Nowadays the energy problem is one of the most important global problems, which together with the rapid climate change lead to the need for power generation as more economical and environmentally friendly way. Therefore, the Renewable Energy Sources and especially wind power have a great role in this objective and radically change both the European and the global energy map. In this paper we study a wind turbine device, which consists at first of a squirrel cage induction generators (SCIG), a frequency converter (back-to-back converter) and an three-phase R-L filter on the grid side and then me add, after the filter, a capacitor bank connected in star, a three-phase R-L load at the same point with the capacitor banks and the transmission line for grid connection. Aim of this thesis is to study the complete wind turbine system in the d-q rotating vertical axes system through the Park transformation. Then we proceed to the calculation of the equations in state space and eventually propose a control system based on PI controllers. Finally, we simulate the complete system with the MATLAB/Simulink and then we present simulations of the responses and draw conclusions.

Many scholars exclude New York painter Philip Guston (1913-80) from the artistic tradition of Abstract Expressionism due to his absence from New York City during the group's early formative years. This thesis asserts, however, that Guston's role in Abstract Expressionism can be firmly established through his unique interpretation of the formative influence of surrealist automatism. Though never engaging with the surrealists directly, Guston explored automatist ideas upon meeting New York School experimental music composers John Cage and Morton Feldman. This trio's engagement with the Zen Buddhist concepts of unimpededness and interpenetration influenced Guston to create compositions through chance operations, a process Cage would call "indeterminacy." My aim is to enrich an understanding of Guston's idiosyncratic relationship to Abstract Expressionism and, ultimately, to offer a more expansive definition of Abstract Expressionism in general, allowing for a broader understanding of the formation of American modernism.

Les cages moléculaires covalentes ou de coordination sont des molécules particulièrement intéressantes lorsqu’elles présentent une cavité active en reconnaissance moléculaire ou en réactivité chimique. Le projet consiste en la synthèse et l’étude d’un nouveau type de cage moléculaire, constituée de deux porphyrines reliées par des liaisons covalentes mais flexibles et de huit ligands 3-pyridyles (L) permettant de contrôler la taille de la cavité par un stimulus externe. L’étape-clé de la synthèse de cette cage est la formation d’un dimère de porphyrine par effet template, de sorte à favoriser la fermeture de la cage. Des cations métalliques coordinés par les groupements L ou un ligand ditopique comme le DABCO coordiné entre les métallo-porphyrines ont été utilisés pour pré-assembler le dimère. Ce dernier ayant été obtenu, les chaînes polyéther ont été reliées deux par deux par métathèse des oléfines. Une structure cristallographique de la cage covalente complexant le DABCO a pu être obtenue. La cage synthétisée a, par la suite, été démétallée et le DABCO retiré, la conformation adoptée par cette dernière molécule varie par rapport à son précurseur. / Covalent or coordination molecular cages are particularly interesting molecules when they incorporate an active cavity in molecular recognition or in chemical reactivity. The project consists in the synthesis and the study of a new type of molecular cage, built from two porphyrins linked together by covalent but flexible bonds and eight 3-pyridyl ligands (L) allowing a control of the size of the cavity by an external signal. The key-step in the cage synthesis is the formation of a template dimer in order to favour the covalent cage closing. Several metallic cations coordinated by the L moieties or a ditopic ligand such as DABCO coordinated between two metalloporphyrins have been used for the preorganization of a dimer. Once the latter compound formed, the polyether chains have been linked two-by-two by alkene metathesis. A crystallographic structure of the covalent cage complexing the DABCO has been obtained. Furthermore, the synthesized cage was demetallated and the DABCO removed, the conformation adopted by this molecule doesn’t change a lot from its precursor.

Orientador: Ricardo Machado Leite de Barros / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação Fisica / Made available in DSpace on 2018-08-09T17:18:56Z (GMT). No. of bitstreams: 1 Sarro_KarineJacon_D.pdf: 1134388 bytes, checksum: b567c37751844e9b74d352b031f141d7 (MD5) Previous issue date: 2007 / Resumo: O presente trabalho teve como objetivo propor e validar um novo método para análise cinemática tridimensional da movimentação da caixa torácica durante a respiração e mostrar uma aplicação do mesmo. A análise cinemática foi utilizada para descrever a movimentação tridimensional das costelas durante a respiração. As coordenadas 3D de marcadores posicionados sobre as costelas e vértebras foram utilizadas para calcular as distâncias transversais e ântero-posteriores da caixa torácica e a orientação das costelas em função do tempo. O método identificou um sinal coerente com o ciclo respiratório para todas as distâncias calculadas e também para os ângulos das costelas ao redor de um eixo quasi-transversal representando os movimentos de elevação e abaixamento das costelas. Também foi capaz de medir a maior variação das distâncias ântero-posteriores e transversais da caixa torácica durante respirações em capacidade vital quando comparadas a respirações em volume corrente. Foram realizados testes para avaliar variáveis relacionadas aos erros de medição do sistema de análise cinemática utilizado. Imagens de ressonância magnética do tronco foram utilizadas para calcular a movimentação relativa entre os marcadores de superfície e as costelas (deslizamento de pele). Os resultados revelaram um erro sistemático abaixo de 1 mm e um desvio padrão experimental de 2,5 mm, o que gerou erros máximos de 2º na medição da variação angular das costelas. A movimentação relativa média entre os marcadores, assumida como a distância entre o marcador e a costela em capacidade pulmonar total menos a distância entre o marcador e a costela em capacidade residual funcional, foi igual a 3,9 mm, valor menor que os relatados na literatura para os membros inferiores ou coluna vertebral. Esses resultados validam o método, mostrando a viabilidade em se usar a análise cinemática para avaliar movimentações das costelas acima de 2º. Uma vez validado, o método foi aplicado a um grupo de sujeitos saudáveis e distinguiu alguns sujeitos com movimentação paradoxal das costelas. Aplicado a um grupo de nadadores, foi capaz de evidenciar alterações nos movimentos respiratórios desse grupo, identificando maior variação angular das costelas e maior correlação entre as curvas dos ângulos das costelas (p<0,05) quando comparado ao grupo controle. Os nadadores também apresentaram maior correlação entre a variação angular das costelas e os volumes parciais do tronco, reforçando o potencial da metodologia em identificar alterações nos padrões respiratórios. Concluindo, este estudo validou o uso da análise cinemática 3-D para avaliar a movimentação das costelas e a coordenação entre elas durante a respiração bem como evidenciou seu potencial na identificação de diferentes comportamentos da movimentação das costelas, mostrando que a prática de natação induziu um padrão otimizado de movimentação da caixa torácica / Abstract: The present work aimed to propose and validate a novel method to the 3D kinematical analysis of the rib cage motion during breathing and to show an example of application. The kinematical analysis was used to describe the 3D motion of the ribs during breathing. The 3D coordinates of surface markers positioned on the ribs, sternum and vertebrae were used to calculate the transversal and anterior-posterior distances of the rib cage and the orientation of the ribs in function of time. The method identified a signal coherent with the breathing cycle for all the distances measured and for the angles of the ribs around the quasi-transversal axis representing the upward and downward movements of the ribs. The method was also able to identify the higher variation of the transversal and anterior-posterior distances of the rib cage during breathing at vital capacity when compared with breathing at tidal volume. Some tests were performed to evaluate variables related to the measurement errors of the system. Magnetic resonance images of the trunk were used to calculate the relative motion between the surface markers and the ribs (soft tissue artifact). The results revealed less than 1 mm of systematic error and a experimental standard deviation of 2.5 mm, which generate maximal errors of 2º on the angular variation of the ribs. The soft tissue artifact was assumed as the distance between the marker and the rib at total lung capacity minus the distance between the marker and the rib at functional residual capacity, and the absolute mean value found was 3.9 mm. This value is smaller than that one found in the kinematics of other segments. The method was applied in a group of swimmers and a control group of non-athletes and was able to distinguish subjects with a paradoxal movement and showed that swimmers presented greater angular variation for all ribs, and greater correlation between the curves of the rib angles (p<0.05). The swimmers also presented higher correlation between the angular variation of the ribs and the variation of the separate volumes of the trunk. In conclusion, this study has validated the use of 3-D kinematic analysis to evaluate the movement of the ribs and their coordination during breathing as well as has shown its potential to identify differences in the behavior of the ribs motion, showing that swimming training induced an optimized pattern of motion of the rib cage / Doutorado / Biodinamica do Movimento Humano / Doutor em Educação Física

Ce travail s’inscrit dans le domaine des cages moléculaires, édifices dont la géométrie définit unecavité tridimensionnelle capable de contenir d’autres entités.L’objectif de cette thèse est la synthèse de cages moléculaires covalentes possédant despropriétés d’encapsulation et une taille modulables. Les cages synthétisées avec succèsincorporent des porphyrines de zinc ou bases libres, ainsi que huit ligands triazoles périphériques.Des molécules ont pu être encapsulées par coordination aux porphyrines ou par interactions π, cequi démontre la capacité de la cage à s’adapter à l’invité grâce à sa flexibilité. La coordinationd’ions argent(I) permet de passer d’une conformation aplatie à une conformation ouverte. Lecaractère commutable de la cage a été démontré par décoordination de ces ions. Enfin, lacoordination d’ions argent(I) aux ligands de la cage augmente la stabilité de deux ligandsditopiques, le DABCO et la pipérazine, au sein de la cavité. Elle permet aussi l’accès de la cavité àdes molécules non encapsulées en l’absence d’argent(I). Ces résultats démontrent le contrôleallostérique de l’encapsulation de molécules par un stimulus chimique. / This work belongs to the field of molecular cages, hollow structures enclosing a three-dimensionalcavity able to encapsulate other molecules.The goal of this thesis include the synthesis of molecular covalent cages with a controllablecavity size able to perform switchable guest encapsulation. A DABCO-templated click reactionafforded three flexible covalent cages, endowed with two zinc(II) or free-base porphyrins and eightperipheral triazole ligands. Various guest molecules could be encapsulated by coordination toporphyrins or π-π interactions, in an induced-fit mechanism, probing the ability of the cage to adaptto the guest thanks to its flexibility. Coordination of silver(I) ions to the peripheral triazoles allow toswitch from a flattened to an open and locked conformation. Removal of the ions proved thecommutability of the cage. Finally, coordination of silver(I) ions to triazole ligands increase thestability of two ditopic ligands, DABCO and piperazine, inside the cavity. It also allowed the accessto the cavity of molecules that were not otherwise encapsulated. These results shows the allostericcontrol of guest encapsulation by a chemical stimulus.

No description available.

FAULT LINE examines the fragile humanity connected to the themes of sexuality, violence, addiction, family dynamics, and death. The book is not broken into sections; rather, as poems build upon one another to explore a narrative arc, FAULT LINE tracks a single speaker’s experience from girlhood to the verge of independent womanhood. The speaker employs formal structures such as the prose poem, sestina, and particularly the list poem to examine the fluidity of inner experience and also the culture at large while challenging the narrow definitions of femininity and masculinity. FAULT LINE works to not only address the question of blame but also the literal breaks in lines of poetry. By looking at a single speaker’s struggle, the book, like life, is both humorous and horrifying.

The work presented in this thesis involves the development of a new analytical method for predicting the transient behaviour of squirrel cage induction motors subjected to pulsating mechanical loads such as a reciprocating compressor. The objective of this project is to develop analysis that will better inform the subsequent design method for determining the rating of industrial induction motors driving an oscillatory load. The analytical approach used to determine the transient response of the motor is based upon the harmonic coupling inductance method which is capable of accommodating any stator winding arrangement used in industrial motor designs. The analytical work described in this thesis includes the response of an induction motor subjected to a general oscillating load in terms of the damping and synchronous torque components. These torque components can be used to determine the additional system inertia required to limit the motor speed and current oscillations to predetermined levels. The work further identifies the motor-load natural resonant frequency and demonstrates the potential issues when driving a general oscillatory load at or close to this frequency. The analytical model was cross-checked using software modelling in Matlab for an industrial squirrel cage induction motor driving a selection of compressor loads. The simulation results were finally correlated with a detailed experimental validation in the laboratory using a squirrel cage induction motor connected to a permanent magnet synchronous motor controlled electronically to simulate general oscillatory load.

Recent failures of large induction machines due to rotor bar breaks have become a major industrial concern in South Africa. These failures have occurred while applying current condition monitoring methods. This would imply that current theories are either inadequate or badly implemented. This thesis investigates two currently used condition monitoring strategies which focus on monitoring the stator current and axial vibration to detect bar breaks as well as a third method which involves putting destructive shaft voltages to good use and using this signal to diagnose rotor defects. This document begins by familiarizing the reader with two conventional approaches which involve monitoring the stator current and the axial vibration to detect rotor bar breaks. Thereafter the origins of shaft voltage are discussed and its use as a condition monitoring tool is first theoretically derived and then validated by finite element simulations. A thorough discussion of the measurement equipment required is presented and ultimately the performance of these three methods is tested by means of a laboratory measurement as well as two on-site measurements. The results from these measurements suggest that when making proper use of both conventional condition monitoring methods, these methods have a 50% success rate in the detection of rotor bar breaks. The alternative method investigated, which involves monitoring the shaft voltage, has a 75% success rate in the detection of rotor bar breaks. This highlights the use of shaft voltage as a condition monitoring tool. / Dr. S. R. Holm Prof. W. A. Cronje

Novel cage-functionalized azacrown ethers, i.e. 51, 52, 53, 55, 57, 61 and 62, which have various crown cavity and different number of nitrogen atoms incorporated, have been prepared. X-ray structures of 53, 55 and 57 have been obtained for the study of the crown topological structure. The complexation properties of crown 51, 52, 57, 61 and 62 have been evaluated via alkali metal picrate extraction, silver picrate extraction and ESI-MS study. The novel cage-fuctionalized azacrown ethers generally exhibit high avidity and selectivity towards Ag+ versus alkali metal ions and some transition metals i.e. Cu2+, Mn2+, Zn2+, Ni2+ and Pb2+. Crown 61 displays significant avidity and selectivity toward K+ in alkali metal picrate extraction experiments vis-à-vis the remaining alkali metal picrates. Three types of ditopic ion-exchange receptors for sodium hydroxide extraction study have been designed. All of the crown ether molecules have proper cavity for selective sodium complexation and have weakly acidic ionizable alcohols for sodium-proton exchange under strongly basic conditions. Crown 80 and 81 were synthesized; key intermediates for the synthesis of crown 82, 83 and 84 have been prepared. The preparation of 99 afforded an unexpected crown 103. The preparation of 109 had been attempted, but could not be successfully isolated. Four novel cage-functionalized calix[4]arene crown-5, i.e. 113-116, have been synthesized. The structures of 113 and 116 have been established by X-ray crystal structural analysis and NMR spectral analysis. The complexation properties of the four ionic receptors have been studied via alkali metal picrate extraction experiments. Crown 115 and 116 display more than modest avidity toward alkali metal ions and are most selective toward K+ vis-à-vis 113 and 114.