Στην παρούσα Διπλωματική Εργασία μελετάται και αναλύεται η Ηλεκτρομαγνητική συμπεριφορά βασικών κυκλωμάτων και στοιχείων, τα οποία απαντώνται πάνω σε Πλακέτες Τυπωμένων Κυκλωμάτων. Η σχεδίαση και ανάλυση των μοντέλων γίνεται χρησιμοποιώντας τα Ηλεκτρομαγνητικά λογισμικά πακέτα της Agilent, ΕΜPro και ADS, ενώ για τον υπολογισμό χρήσιμων παραμέτρων χρησιμοποιείται η ελεύθερη εφαρμογή της Agilent, Appcad και η εφαρμογή Linecalc, η οποία είναι ενσωματωμένη στο ADS. Αρχικά, γίνεται μια σύντομη αναφορά στις σύγχρονες τάσεις που επικρατούν στην περιοχή των Τυπωμένων Κυκλωμάτων και περιγράφεται η χρησιμότητα των τοπολογιών που αναλύονται. Επιπροσθέτως, αναφέρεται η αναγκαιότητα και οι περιπτώσεις κατά τις οποίες είναι απαραίτητη η διεξαγωγή ηλεκτρομαγνητικής ανάλυσης των κυκλωμάτων, αλλά και τα προτερήματα που αυτή προσφέρει. Παρουσιάζεται η χρησιμότητα και αναλύεται η δομή μιας μαιανδρικής μικροταινιακής γραμμής εισαγωγής καθυστερήσεως και συγκρίνονται οι εκπομπές της ως προς τις εκπομπές μιας ευθείας μικροταινιακής γραμμής. Έπειτα, μελετάται η κατανομή του ρεύματος στο επίπεδο αναφοράς μιας απλούστερης γεωμετρίας μαιανδρικής μικροταινιακής γραμμής και παρουσιάζονται φαινόμενα περισσότερο αισθητά σε υψηλές συχνότητες. Έπειτα, μελετώνται οι εκπομπές από μια γεωμετρία μικροταινιακής γραμμής, η οποία διασχίζει σχισμή στο επίπεδο αναφοράς. Επίσης, μελετάται η συμπεριφορά μικροταινιακής γραμμής ευρισκόμενης στο χείλος μιας πλακέτας. Επιπλέον, μελετάται ένα πρόβλημα σχεδιάσεως αποτελεσματικής ηλεκτρομαγνητικής θωρακίσεως και υπολογίζεται η αποδοτικότης της θωρακίσεως. Σε επόμενο κεφάλαιο, μελετάται η επίδραση ασυνεχειών ευρισκόμενων σε μια δομή μικροταινιακής γραμμής και σχεδιάζεται ένα μεταϋλικό, ενώ παράλληλα προσδιορίζονται χαρακτηριστικές παράμετροι της δομής. Ακολούθως, σχεδιάζονται τρία είδη δομών που περιλαμβάνουν οπές via. Αυτές είναι: μία απλή via , μια δομή διαφορικών via και μια εφαρμογή απομονώσεως δυο συζευγμένων ταινιογραμμών χρήσει ενός φράχτη από οπές via. Τέλος, προσομοιώνεται η λειτουργία μιας πραγματικής πλακέτας και υπολογίζονται οι ηλεκτρομαγνητικές της εκπομπές στο μακρινό πεδίο. Παράλληλα, παρουσιάζονται ορισμένα στατιστικά του χρόνου εκτελέσεως και των απαιτούμενων πόρων για την προσομοίωση, γίνονται σχόλια και επισημάνσεις που αφορούν στα χαρακτηριστικά των χρησιμοποιούμενων αλγορίθμων για τη διεξαγωγή μετεπεξεργασίας των δεδομένων και δίνονται χρήσιμες συμβουλές όσον αφορά σε χαρακτηριστικά του λογισμικού Προσομοιώσεως και σε δυνατότητες επιταχύνσεως της Προσομοιώσεως που προσφέρονται από το ίδιο το λογισμικό. / -

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Within a complex electronic system, sub-system communication forms the backbone of the functionality of any satellite. It allows multiple processors to run simultaneously and data to be shared amongst them. Without it, a single processor would have to control the entire satellite. Not only would such a design then be overly complicated, but the processor would also not have sufficient capacity to service all the components efficiently. Furthermore the detrimental effects that radiation have on integrated circuits are well documented and can be anything from a single bit flip to a complete integrated circuit failure. If not repaired, a failure on a sub-system communication bus could lead to the loss of the entire satellite. Die goal is to create more radiation resistant Controller-Area-Network (CAN) node. Since a full triple modular redundant design will have a large footprint and high power consumption, a combination of techniques will be applied and tested. The goal is to achieve improved footprint utilisation over triple modular redundancy, while still maintaining good resistance to Single Event Upsets (SEU). By applying simulation, it was sufficiently proven that the implementation of the individual techniques used functioned according to expectations. These techniques included error detection and correction using Hamming Codes, single event transient filter and triple modular redundancy. Having applied these mitigation techniques, the footprint of the CAN controller increased by only 116%. Simulation showed that the Error Detection and Correction and Triple Modular Redundancy worked effectively with the CAN controller, and that the CAN controller could function as originally intended. Using radiation testing, the design proved to be more resistant to SEUs than the unmitigated CAN controller. It was thus shown that through using a combination of mitigation techniques, it is possible to develop an optimal design with a high level of resistance against Single Event Upsets, utilizing a smaller footprint than implementing Triple Modular Redundancy. / AFRIKAANSE OPSOMMING: Sub-stelsel kommunikasie vorm die basis van die funksionaliteit in ’n komplekse elektroniese stelsel soos ’n satelliet. Dit skep die vermoë om veelvoudige verwerkers gelyktydig te laat funksioneer en inligting tussen hulle te deel. Sonder sub-stelsel kommunikasie, sal ’n enkele verwerker die hele sateliet moet beheer. Dit sal nie net die hele ontwerp oorkompliseer nie, maar die verwerker sal ook nie genoeg kapisteit hê om al die komponente effektief te diens nie. Die newe-effekte van bestraling op geïntegreerde stroombane is goed gedokumenteer en kan wissel van ’n enkele omgekeerde bis, tot die vernietiging van die geïntegreerde stroombaan. Indien die fout in die kommunikasiestelsel nie herstel word nie, kan dit lei tot die verlies van die hele sateliet. Die doel is om ’n meer bestraling bestande Controller-Area-Network (CAN) nodus te skep. Aangesien ’n volle drie-dubbele-modulêre-oortollige ontwerp ’n baie groot area beslaan en hoë krag verbruik het, gaan ’n kombinasie van versagting tegnieke toegepas en ge-evalueer word. Die doel is om beter area benutting as die drie-dubble-modulêre-oortollige ontwerp te kry, terwyl ’n goeie weerstand teen foute behoue bly. Deur middel van simulasies is voldoende bewyse gelewer dat die implimentasie van die individuele versagting tegnieke soos verwag funktioneer. Hierdie tegnieke sluit in, fout opsporing en regstelling deur middel van Hamming kodes, enkele geval oorgangs verskynsel filter asook drie-dubbele-modulêre-oortollige ontwerp. Nadat versagting meganismes toegepas is, het die area verbruik van die CAN beheerder toegeneem met slegs 116%. Simulasies het bewys dat Fout Opsporing en Regstelling en Drie-Dubbele-Modulêre-Oortollige ontwerp tegnieke binne die CAN beheerder korrek funktioneer, terwyl die CAN beheerder self funktioneer soos dit oorspronklik gefunksioneer het. Deur middel van bestralingstoetse, is dit bewys dat die ontwerp meer bestand is teen foute geïnduseer deur bestraling as die onbeskermde CAN beheerder. Dit is dus bewys dat deur gebruik te maak van verskeie versagting tegnieke dit moontlik is om ’n optimale ontwerp te implimenteer, met ’n hoë weerstand teen foute, maar met ’n laer area verbruik as die van ’n Drie-dubbele-Modulêre-Oortollige ontwerp.

Made available in DSpace on 2014-10-09T12:41:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:03Z (GMT). No. of bitstreams: 1 04674.pdf: 2960498 bytes, checksum: 31da12ce5904c3db2729e9982663d7fe (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T23:43:11Z No. of bitstreams: 1 AbimaelAmaroXavierBarbosa_DISSERT.pdf: 16696766 bytes, checksum: e91d93bcbf5b7637837b4451d91329f2 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-18T21:16:15Z (GMT) No. of bitstreams: 1 AbimaelAmaroXavierBarbosa_DISSERT.pdf: 16696766 bytes, checksum: e91d93bcbf5b7637837b4451d91329f2 (MD5) / Made available in DSpace on 2016-05-18T21:16:15Z (GMT). No. of bitstreams: 1 AbimaelAmaroXavierBarbosa_DISSERT.pdf: 16696766 bytes, checksum: e91d93bcbf5b7637837b4451d91329f2 (MD5) Previous issue date: 2015-07-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Criado no in?cio da d?cada de setenta, o Sistema de Posicionamento Global (GPS) chega aosmeados da segunda d?cada do s?culo 21 com sua populariza??o atrav?s de softwares que podemser facilmente utilizados em aparelhos celulares e em pain?is de autom?veis. Al?m disso, anavega??o a?rea brasileira utiliza tal sistema de sat?lites como um de seus meios de orienta??o.Tais fatos tornam os problemas relacionados ao uso de servi?os de localiza??o por GPS emassuntos de interesse social. Dentre esses problemas est?o as cintila??es, que s?o s?bitasmudan?as na amplitude e/ou fase da onda eletromagn?tica que ocorrem quando esta atravessaregi?es de irregularidades na densidade eletr?nica da ionosfera, camada atmosf?rica situada entre50 Km e 2000 Km de altitude. Entre as causas da forma??o de tais irregularidades, conhecidascomo bolhas de plasma, h? o acentuado crescimento do campo el?trico zonal durante as ?ltimashoras da tarde devido ao efeito d?namo na camada F e ? diminui??o da condutividade el?trica nacamada E, criando, assim, o pico de pr?-revers?o com intenso aumento da deriva vertical doplasma ionosf?rico antes da sua invers?o, quando a ionosfera desce, ap?s o p?r do Sol,produzindo uma instabilidade, segundo o modelo de Rayleigh-Taylor. No Brasil, a ocorr?nciadesse processo ? mais intensa entre os meses de Setembro e Abril, de modo que as cintila??ess?o mais frequentes nesse per?odo. Estudos tem relacionado o comportamento desse fen?menoeletromagn?tico na regi?o brasileira com tempestades geomagn?ticas por meio de modelos decampos el?tricos perturbados nas proximidades do equador magn?tico. Este trabalho, ent?o,visando identificar a rela??o entre cintila??es de GPS em Natal-RN (Brasil) e perturba??esgeomagn?ticas de quaisquer intensidades e varia??es, fez analises do comportamento ionosf?ricoe das varia??es do ?ndice Dst (Disturbance storm time) concernente a ?pocas distintas do ciclosolar do per?odo entre os anos de 2000 e 2014. Parte dos dados desta pesquisa se originou noobservat?rio da UFRN, a partir de uma placa GEC Plessey ligada a uma antena ANP -C 1143modificada pelo grupo Cornell University?s Space Plasma Physics de modo a operar o ScintMon,um programa de monitoramento de GPS. Neste estudo, portanto, foram constatados v?rios casosde cintila??es inibidas ap?s a fase principal de tempestades magn?ticas, fato que, juntamente comoutros, corroboraram com a categoriza??o de Aarons (1991) e com os modelos de d?namopertubado (de acordo com Bonelli, 2008) e de penetra??o over-shielding, defendido por Kelley etal. (1979) e Abdu (2011) [4]. Al?m dessas constata??es, foram notados diferentes aspectosmorfol?gicos em tais perturba??es no sinal de GPS de acordo com atividades magn?ticasprecedentes. Tamb?m foi constatada uma rela??o moderada entre a taxa de varia??o do Dst (dehor?rio espec?fico) e o S4 m?dio do sinal noturno, por meio de uma fun??o polinomial. Talconstata??o, portanto, corroborando com Ilma et al. (2012) [17], ? uma importante evid?ncia deque as cintila??es de GPS n?o s?o diretamente controladas por indu??o magn?tica detempestades. Ao concluir este trabalho, essa rela??o tamb?m se mostrou como um meio deprevis?o parcial de cintila??es. / To identify the relationship between GPS scintillation in Natal-RN (Brazil) and geomagnetic disturbances of any intensities and variations, this work made analysis of the ionospheric behavior and magnetic indexes (Dst , AE and Bz of the interplanetary magnetic field) concerning to different periods of the solar cycle between 2000 and 2014. Part of the data of this research originated at the UFRN observatory, from a GEC Plessey board connected to an ANP -C 114 antenna, modified by Cornell University?s Space group Plasma Physics in order to operate the ScintMon, a GPS monitoring program. This study, therefore, found several cases of inhibited scintillations after the main phase of magnetic storms, a fact that, along with others, corroborated with categorization of Aarons (1991) and models of disturbed dynamo (according to Bonelli, 2008) and over-shielding penetration, defended by Kelley et al. (1979) and Abdu (2011) [4]. In addition to these findings, different morphologies were noted in such disruptions in the GPS signal in accordance with previous magnetic activities. It also found a moderate relationship (R2 = 0.52) between the Dst rate (concerning to specific time) and the average of S4 through a polynomial function. This finding therefore, corroborating Ilma et al. (2012) [17], is an important evidence that the scintillation GPS are not directly controlled by magnetic induction of storms. Completing this work, this relation did show itself as a way of partial predicting of scintillations.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The process of welding with solid wire (GMAW) and cored wire (FCAW) processes that compete in quality, productivity and operational, need reliable information of its main features and applications for a given welding condition. Thus, the goal is to compare the capability of each process in the horizontal welding carbon steel ABNT 1020, varying the type of shielding gas on the same level of welding current and voltage to maintain a constant deposition rate per unit length. For this study we used the wire E71T-1 and ER 70S-6 under the shielding 100% CO2 gas and Ar +25% CO2 in two bands of four current and voltage ranges. We evaluated the stability of metal transfer mode and short-circuit capacity through income and presence of deposit discontinuity. In general, the process using a tubular wire had a higher deposition rate compared to solid wire, but with lower performance deposit. It was noted that, the same current range and with increasing voltage range, there was a change in transfer characteristics for both processes. With regard to straining of the weld beads, the solid wire bends showed better with lower voltage ranges. Cored wire for the values of runoff was similar, with a condition better than solid wire for higher values of welding voltage (region of predominance of metal transfer carried by the flow without short circuit). The shielding gas 100% CO2, for both processes, which was provided better performance and higher deposit with transfer voltage ranges with a predominance of short-circuit. / Os processos de soldagem com arame maciço (GMAW) e arame tubular (FCAW), processos que competem entre si em termos de qualidade, produtividade e operacionalidade, necessitam de informações seguras de suas principais características e aplicações para uma determinada condição de soldagem. Desta forma, o objetivo deste trabalho é comparar a potencialidade de cada processo na soldagem horizontal de aço carbono ABNT 1020, variando o tipo de gás de proteção sob um mesmo nível de corrente e tensão de soldagem, mantendo constante a taxa de deposição por unidade de comprimento. Para a realização deste estudo foram utilizados os arames E71T-1 e ER 70S-6 sob as proteções gasosas 100%CO2 e Ar+25%CO2 em duas faixas de corrente e quatro faixas de tensão. As características avaliadas foram a regularidade de transferência metálica no modo curto-circuito e a capacidade produtiva através do rendimento de depósito e presença descontinuidades. De maneira geral, o processo utilizando arame tubular apresentou maior taxa de deposição em relação ao arame maciço, porém com menor rendimento de depósito. Também se observou que, na mesma faixa de corrente e com a elevação da faixa de tensão, houve uma mudança nas características de transferências para os dois processos. Em relação ao escorrimento dos cordões de solda, o arame maciço apresentou melhores cordões com menores faixas de tensão. Para o arame tubular os valores dos escorrimentos foram próximos, tendo uma condição melhor que o arame maciço para maiores valores de tensão de soldagem (região de predominância de transferência metálica conduzida pelo fluxo sem curto-circuito). O gás de proteção 100%CO2, para ambos os processos, foi o que proporcionou melhor rendimento de depósito e maiores faixas de tensão com transferência com predominância de curto-circuito. / Mestre em Engenharia Mecânica

Made available in DSpace on 2014-10-09T12:41:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:03Z (GMT). No. of bitstreams: 1 04674.pdf: 2960498 bytes, checksum: 31da12ce5904c3db2729e9982663d7fe (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Abstract The present thesis describes a method for characterization of liquid crystals in confined spaces by means of NMR of probe atoms and molecules. 129Xe isotope enriched xenon gas and 13C isotope enriched methyl iodide and methane were used as probes. Behavior of solutes and liquid crystals confined to porous materials was investigated using 129Xe and 13C NMR spectroscopy. Uniaxial nematic liquid crystals Phase 4 and ZLI 1115 were used as a medium. Controlled pore glass with well defined and known properties was used as a porous material. The behavior of liquid crystals and solutes in various different size pores, temperatures and magnetic fields at different solute concentrations was explained. The average pore diameter of the material varied from mesopores to macropores. The studied temperature range covered solid, nematic and isotropic phases of bulk liquid crystals, and the highest magnetic field was 2.5 times stronger than the lowest one used (4.70 T). The chemical shifts, intensities, and line shapes of the resonance signals from the solutes were observed to contain lots of information about the effect of confinement on the state of the liquid crystals. Especially the line shape of the 13C resonances of methyl iodide was observed to be very sensitive to the liquid crystal orientation distribution in the pores. By varying experimental conditions the relative contribution of field and the surface forces of pore walls to the orientation of liquid crystal molecules inside the pores was seen to change quite drastically. In addition, it was also observed that when the sample is cooled very rapidly, xenon atoms do not squeeze out from the freezing medium but they are occluded inside the solid lattice, and their chemical shift is very sensitive to crystal structure. Furthermore, because solutes experienced on average isotropic environment inside the smallest pores, isotropic value of the shielding tensor could be determined at exactly the same condition and temperature as anisotropic counterpart between the pore particles. Thus, for the first time in the solution state, shielding anisotropies could be determined as a function of temperature.

Abstract In this thesis, the theory of static magnetic resonance spectral parameters of nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy is investigated in terms of the molecular Breit-Pauli Hamiltonian, which is obtained from the relativistic Dirac equation via the Foldy-Wouthuysen transformation. A leading-order perturbational relativistic theory of NMR nuclear shielding and spin-spin coupling tensors, and ESR electronic g-tensor, is presented. In addition, the possibility of external magnetic-field dependency of NMR parameters is discussed. Various first-principles methods of electronic structure theory and the role of one-electron basis sets and their performance in magnetic resonance properties in terms of their completeness profiles are discussed. The presented leading-order perturbational relativistic theories of NMR nuclear shielding tensors and ESR electronic g-tensors, as well as the theory of the magnetic-field dependent NMR shielding and quadrupole coupling are evaluated using first-principles wave function and density-functional theories.

Abstract The subjects of this thesis are the dynamics of liquid crystals in external electric and magnetic fields as well as the magnetic properties of small molecules, both studied by liquid crystal nuclear magnetic resonance (LC NMR) spectroscopy. Director dynamics of a liquid crystal 5CB in external magnetic and electric fields was studied by deuterium NMR and spectral simulations. A new theory was developed to explain the peculiar oscillations observed in the experimental spectra collected during fast director rotation. A spectral simulation program based on this new theory was developed and the outcome of the simulations was compared with the experimental results to verify the tenability of the theory. In the studies on the properties of small solute molecules, LC NMR was utilised to obtain information about anisotropic nuclear magnetic interaction tensors. The nuclear magnetic shielding tensor was studied in methyl halides, the spin-spin coupling tensor in methyl mercury halides and the quadrupolar coupling tensor in deuterated benzenes. The effects of small-amplitude molecular motions and solvent interactions on the obtained parameters were considered in each case. Finally, the experimental results were compared to the corresponding computational NMR parameters calculated in parallel with the experimental work.

Teeth trauma has become one of the most serious physical problems that people are suffering from in the past years. Early diagnosis and management are desperately needed to improve tooth survival, functionality and avoid the tooth loss. However, the diagnosis of cracked tooth could be challenging due to the small size of the crack. Therefore, a mechanics understanding of the tooth fracture is demanding from the perspective of developing a framework for failure prediction in clinical research and bio-mimetic restorative materials. This study focuses on characterising the anisotropic fracture behaviour and the crack shielding mechanisms in elephant dentin. This is often used as a structural analogue for human dentin due to the similarities in microstructure and chemical composition, in order to avoid the test-piece size restrictions, given the larger size of ivory than human teeth. Compact tension test-pieces were extracted from different locations on the ivory tusk so as to have different crack growth directions relative to the microstructure to inspect the fracture anisotropies. The fracture toughness as a function of the crack extension was assessed in terms of fracture resistance curves (R-curve). The accumulative crack-tip strain fields were also measured for the first time in dentin using digital image correlation technique (DIC) to investigate the capability of crack-tip elastic/plastic deformation before material failure. Investigation of crack morphologies, the interaction between crack and the microstructures, the fracture surfaces using both 2-D and 3-D techniques could provide with insights into extrinsic shielding mechanisms. Surface and volume crack opening displacement (COD) were measured for the first time optically and by X-ray computed tomography to investigate the effect of extrinsic crack-tip shielding. The displacement fields around the crack-tip obtained by DIC were fitted using Westergaard’s analytical solution to extract the effective stress intensity factor, by comparing this to the applied load, the efficiency of the crack-tip shielding could be evaluated. A novel cohesive element model (traction-separation law) was then established based on the COD results to simulate the physical process of crack-tip shielding. It is the first time the cohesive model has been adapted to studying the direct crack behaviour measured by in-situ experiment to predict the crack growth. This model was then validated using the crack-tip strain field and R-curve obtained from the experiment measurement.