Descreve-se neste trabalho um estudo experimental da Emissão Eletrociclotrônica (EEC) no tokamak TCABR. Um radiômetro de EEC foi instalado, calibrado e utilizado para o estudo do plasma em descargas térmicas. O radiômetro é do tipo heteródino de varredura operando na faixa de 50-85 GHz, no modo extraordinário e na segunda harmônica. Determinou-se a temperatura de ruído do radiômetro e também sua estabilidade em amplitude e freqüência. Foi medida a largura de banda em freqüência do radiômetro (resolução espacial horizontal). A antena utilizada é do tipo gaussiana sendo que o raio da cintura do feixe gaussiano e a posição do foco foram experimentalmente determinados (W0 ~ 1 cm e d ~ 37 cm, respectivamente). A posição da cintura da antena foi posicionada próxima do centro geométrico do vaso. Foi feita a calibração absoluta do equipamento considerando-se os efeitos das janelas de diagnóstico (reflexão e absorção). O sistema pode operar em modo varredura, para a obtenção de perfis radiais de Te ou modo freqüência única onde se tem alta resolução temporal. As medidas da radiação EC foram feitas, na sua maioria, em descargas com densidade eletrônica média entre 1.10+19 m-3 e 1,5.1019 m-3 de forma a se ter acessibilidade da radiação EC e também minimizar-se a presença de elétrons fugitivos. Para ne > 1,5.1019 m-3 (com B0 = 1,14 T) verifica-se o corte parcial da radiação EC. Nesta condição, o corte na EEC foi utilizado na determinação do perfil radial da densidade eletrônica e aplicado em três diferentes situações: descargas com injeção adicional de gás, com a aplicação do eletrodo de polarização e em descargas com injeção de ondas de radiofreqüência na região das ondas de Alfvén para o TCABR. Usando um perfil parabólico típico para a densidade eletrônica, observou-se que, para descargas com injeção adicional de gás ou em descargas com a aplicação de ondas de radiofreqüência tem-se 0,85 < alfa < 1, e para descargas com aplicação do eletrodo de polarização obteve-se alfa ~ 0,6. Foram feitas observações simultâneas da temperatura eletrônica, a partir do sinal da EEC, e das oscilações de Mirnov (freqüência ~ 11,7 kHz) em descargas térmicas com q(r=0) > 1. Os resultados indicam a presença de um modo de ruptura dominante em rs ~ 9,5 cm com a largura da ilha magnética de W ~ 2,0-2,5 cm. Estes resultados experimentais obtidos estão em acordo com os resultados indicados por teorias de transporte na região das ilhas magnéticas. Observou-se também que a localização da ilha magnética coincide com uma região onde o perfil radial da temperatura de plasma é aproximadamente plano. Num outro cenário, com q(r=0) < 1, observaram-se oscilações dente de serra com período de ~ 0,44 ms, tempo de queda de ~ 0,12 ms, e raio de inversão em r ~ 4 cm. Neste tipo de descargas observou-se que, no perfil radial da amplitude das oscilações da Te, |DeltaTe|, devido à propagação dos pulsos dente de serra, apresentavam posições de mínimos e que estes coincidiam com as posições onde ocorrem patamares no perfil radial da temperatura eletrônica. Partindo destes resultados, juntamente com o perfil de q(r), dão-nos os modos racionais (m/n), posições (r) e larguras(W) para as ilhas magnéticas, presentes nestas descargas, a saber: m/n = 4/3 (r ~ 9 cm, W4/3 ~ 0,9 cm), m/n = 3/2 (r ~ 11,8 cm, W3/2 ~ 0,9 cm) e m/n = 2/1 (r ~ 13,7 cm, W2/1 ~ 1,4 cm). Este novo método, aqui proposto, permite a determinação direta da posição e da largura das ilhas magnéticas, em descargas onde a instabilidade dente de serra encontra-se presente.¶ / In this work, an experimental study of the Electron Cyclotron Emission (ECE) in the TCABR Tokamak, is described. An ECE sweeping heterodyne radiometer, operating in the 50-85 GHz frequency range, was installed, calibrated and used to detect ECE radiation in the second harmonic extraordinary mode from thermal plasma discharges. The noise temperature, amplitude and frequency stability of the radiometer were determined. The frequency bandwidth (horizontal space resolution) was measured. A Gaussian Antenna is used and the gaussian beam waist radius (W0 ~ 1 cm) and the focus position (d ~ 37 cm) were experimentally determined. The focus of the antenna was positioned close to the center of the vacuum vessel. The absolute calibration of the equipment was done and the effect of the diagnostic window was considered (reflections and absorptions). The system can operate in sweeping mode, in order to obtain the radial electron temperature profiles, and also in the single frequency mode to obtain temporal electron temperature profiles with high time resolution. Due to the TCABR accessibility conditions and also to avoid runaway electrons, most of the ECE measurements were obtained in discharges with line electron density between 1.0x10+19 m-3 and 1.5x1019 m-3. For ne > 1.5x1019 m-3 (with B0 = 1.14 T) the cutoff in the ECE radiation was observed. The ECE cutoff was used to determine the radial profile of the electron density and applied to three different situations: discharges with additional gas puffing, with the application of a biasing electrode and in discharges with radio-frequency wave injection. Using a parabolic profile it was observed that, 0.85 < alfa < 1.0 for discharges with additional gas injection or with RF injection, and alfa ~ 0.6 for the electrode biasing experiments. The electron temperature profiles and Mirnov oscillations (f ~ 11.7 kHz) were simultaneously measured in discharges with q (r=0) > 1. The position and the width of the magnetic island were therefore calculated. The results indicate the presence of a dominant tearing mode in rs ~ 9.5 cm and the magnetic island width W ~ 2.0-2.5 cm. These experimental results are in agreement with the theoretical results foreseen by models of heat transport in the presence of magnetic islands. It was also observed that, the position of the magnetic island coincided with the region where the temperature radial profile is approximately flat. In another plasma scenario, with q(r=0) < 1, sawteeth oscillations with a period ~ 0.44 ms, crash time ~ 0.12 ms, inversion radius r ~ 4 cm, were measured. Peculiarities in the Te radial profile associated with the amplitude of Te oscillations, |DeltaTe|, due to the sawtooth instability, were observed. It was verified that the minimum values of the |DeltaTe| profile coincided with the region where the temperature radial profile was approximately flat. These results together with the q(r) profile yielded the following mode numbers (m/n), positions (r) and widths (W) of the magnetic islands: m/n = 4/3 (r ~ 9 cm, W4/3 ~ 0.9 cm), m/n = 3/2 (r ~ 11.8 cm, W3/2 ~ 0.9 cm) and m/n = 2/1 (r ~ 13.7 cm, W2/1; ~ 1.4 cm). A novel method to determine the position and width of the magnetic islands, in discharges with the presence of sawtooth instability, is presented here.

The Ku band microwave remote sensor, SeaWinds, was developed at the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL). Two identical SeaWinds instruments were launched into space. The first was flown onboard NASA QuikSCAT satellite which has been orbiting the Earth since June 1999, and the second instrument flew onboard the Japanese Advanced Earth Observing Satellite II (ADEOS-II) from December 2002 till October 2003 when an irrecoverable solar panel failure caused a premature end to the ADEOS-II satellite mission. SeaWinds operates at a frequency of 13.4 GHz, and was originally designed to measure the speed and direction of the ocean surface wind vector by relating the normalized radar backscatter measurements to the near surface wind vector through a geophysical model function (GMF). In addition to the backscatter measurement capability, SeaWinds simultaneously measures the polarized radiometric emission from the surface and atmosphere, utilizing a ground signal processing algorithm known as the QuikSCAT / SeaWinds Radiometer (QRad / SRad). This dissertation presents the development and validation of a mathematical inversion algorithm that combines the simultaneous active radar backscatter and the passive microwave brightness temperatures observed by the SeaWinds sensor to retrieve the oceanic rainfall. The retrieval algorithm is statistically based, and has been developed using collocated measurements from SeaWinds, the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) rain rates, and Numerical Weather Prediction (NWP) wind fields from the National Centers for Environmental Prediction (NCEP). The oceanic rain is retrieved on a spacecraft wind vector cell (WVC) measurement grid that has a spatial resolution of 25 km. To evaluate the accuracy of the retrievals, examples of the passive-only, as well as the combined active / passive rain estimates from SeaWinds are presented, and comparisons are made with the standard TRMM rain data products. Results demonstrate that SeaWinds rain measurements are in good agreement with the independent microwave rain observations obtained from TMI. Further, by applying a threshold on the retrieved rain rates, SeaWinds rain estimates can be utilized as a rain flag. In order to evaluate the performance of the SeaWinds flag, comparisons are made with the Impact based Multidimensional Histogram (IMUDH) rain flag developed by JPL. Results emphasize the powerful rain detection capabilities of the SeaWinds retrieval algorithm. Due to its broad swath coverage, SeaWinds affords additional independent sampling of the oceanic rainfall, which may contribute to the future NASA's Precipitation Measurement Mission (PMM) objectives of improving the global sampling of oceanic rain within 3 hour windows. Also, since SeaWinds is the only sensor onboard QuikSCAT, the SeaWinds rain estimates can be used to improve the flagging of rain-contaminated oceanic wind vector retrievals. The passive-only rainfall retrieval algorithm (QRad / SRad) has been implemented by JPL as part of the level 2B (L2B) science data product, and can be obtained from the Physical Oceanography Distributed Data Archive (PO.DAAC).

Indiana University-Purdue University Indianapolis (IUPUI) Indiana University School of Dentistry Master Degree Thesis. / Detection of caries at an early stage is unequivocally essential for early preventive intervention. Longitudinal assessment of caries lesions, especially under the opaque preventive sealant, would be of utmost importance to the dental community. OBJECTIVES: The aim of this two-part in-vitro study is to evaluate the performance of multiple detection methods: The International Caries Detection and Assessment System (ICDAS); two quantitative light-induced fluorescence systems QLF; Inspektor™ Pro and QLF-D Biluminator™2 (Inspektor Research Systems B.V.; Amsterdam, The Netherlands); and photothermal radiometry and modulated luminescence (PTR/LUM) of The Canary System® (Quantum Dental Technologies; Toronto, Canada). All these are to be evaluated on their detection of caries on posterior human permanent teeth for 1) of primary occlusal lesions, and 2) under the sealant of primary occlusal lesions. METHODS: One hundred and twenty (N = 120) human posterior permanent teeth, selected in compliance with IU-IRB “Institutional Review Board” standards, with non-cavitated occlusal lesions ICDAS (scores 0 to 4) were divided into two equal groups. The second group (N = 60) received an opaque resin dental sealant (Delton® Light-Curing Pit and Fissure Sealant Opaque, Dentsply, York, PA). All lesions were assessed with each detection method twice in a random order except for ICDAS, which was not used following the placement of the sealant. Histological validation was used to compare methods in regard to sensitivity, specificity, % correct, and the area under receiver- operating characteristic curve (AUC). Intra-examiner repeatability and inter-examiner agreement were measured using intraclass correlation coefficient (ICC). RESULTS: 1) Of primary occlusal lesions, sensitivity, specificity, and AUC values were respectively: 0.82, 0.86 and 0.87 (ICDAS); 0.89, 0.60 and 0.90 (Inspektor Pro); 0.96, 0.57 and 0.94 (QLF-D Biluminator 2); and 0.85, 0.43 and 0.79 (The Canary System). Intra-examiner repeatability and inter-examiner agreement were respectively: 0.81 to 0.87: 0.72 (ICDAS); 0.49 to 0.97: 0.73 (Inspektor Pro); 0.96 to 0.99: 0.96 (QLF-D Biluminator 2); and 0.33 to 0.63: 0.48 (The Canary System). 2) Of primary occlusal lesions under the opaque dental sealants, sensitivity, specificity, and AUC values were respectively: 0.99, 0.03 and 0.67 (Inspektor Pro); 1.00, 0.00 and 0.70 (QLF-D Biluminator 2); and 0.54, 0.50 and 0.58 (The Canary System). Intra-examiner repeatability and inter-examiner agreement were respectively: 0.24 to 0.37: 0.29 (Inspektor Pro); 0.80 to 0.84: 0.74 (QLF-D Biluminator 2); and 0.22 to 0.47: 0.01 (The Canary System). CONCLUSION: Limited to these in-vitro conditions, 1) ICDAS remains the method of choice for detection of early caries lesion due to its adequately high accuracy and repeatability. QLF systems demonstrate potential in longitudinal monitoring due to an almost perfect repeatability of QLF-D Biluminator 2. The Canary System performance and repeatability were not acceptable as a valid method of early caries detection. 2) None of the methods demonstrated acceptable ability in detecting of occlusal caries under the opaque sealant. However, QLF-D Biluminator 2, with limitation to these in-vitro conditions and Delton opaque sealant, demonstrated a fair accuracy AUC (0.70) in detecting of caries under sealants at an experimental threshold of 12.5% ΔF.

Neste trabalho são apresentados os resultados do estudo e desenvolvimento dos parâmetros de projeto de um radiômetro solar multiespectral (RSME), baseado em Filtros de Interferência Variável (FIV) de banda-passante que incorpora uma camada ressoante de Fabry-Perot, inclinada em forma de cunha, sintonizável dentro da área opticamente ativa do FIV, aplicável ao sensoriamento ambiental e de aerossóis. Foi apresentada a teoria proposta para a simulação, projeto e deposição pelo método interativo (simulações associada às avaliações de deposições). O FIV foi parametrizado para o RSME, mas pode atender outras aplicações em sensores multicanais e multiespectrais. A construção dos FIV exigiu estudos e adaptações das técnicas clássicas de deposição de filmes finos e de microeletrônica, foi utilizada a PVD/E-Beam. É apresentado um estudo e o emprego de simulações matemáticas e softwares, aplicáveis a FI convencionais correlatas aos FIVs. Estes softwares foram aplicados e avaliados em relação ao projeto dos FIV. Avaliamos a técnica empregada que produz a inclinação na espessura dos FIVs em uma monocamada de 600 nm com um Perfilômetro do LME. Os FIVs caracterizados opticamente com espectrofotômetros, apresentam uma área opticamente ativa de varredura de 120,5 nm no espectro eletromagnético, entre os canais 475,5 nm a 596 nm, pertencentes a 17,3 mm de extensão do FIV. O FIV é um dispositivo óptico projetado com espessura em cunha provocando a resposta espectral linear para a transmitância, com uma taxa de 6,97 nm/mm na sua extensão. Foi proposto que os FIVs caracterizados em conjunto com PD de um PDA, difusor e lente, formem um conjunto detector conectado a um módulo de pré-processamento e coleta de dados (módulo eletrônico) formando assim o RSME parametrizado. O RSME proposto foi avaliado utilizando o FIV02 que opera numa faixa opticamente ativa entre (600 nm a 715 nm), um PDA modelo TSL1401 com 128 PD e um microcontrolador Arduino UNO para o gerenciamento da detecção. Os resultados apontam que o instrumento faz medições equivalentes a outro espectrofotômetro de referência quando medindo um feixe monocromático em 655,4 nm, mas com resolução mais estreita de 0,13 nm por canal. Foi apontada também a necessidade de instrumentação dedicada para outras caracterizações ópticas dos FIV, do conjunto detector do RSME e para a sua calibração. / This paper presents the results of the study and development of the design parameters of a Multi-Spectral Solar Radiometer (MSSR), based on Variable Interference Filter (VIF) pass-bad which incorporates a resonant layer Fabry-Perot inclined in form wedge, tunable within the optically active area of VIF, applicable to enviro nmental sensing and aerosols. The theory proposed was presented for the simulation, design and deposition by interactive method (associated with reviews of depositions simulations). The VIF was parameterized for the MSSR, but can serve other applications in multi-channel and multispectral sensors. The construction of VIF required studies and adaptations of the classic techniques of thin film deposition and microelectronic, was used the PVD / E-Beam. A study and the use of mathematical and simulation software, related to VIFs applicable to conventional IF appears. This software were applied and assessed in relation to the design of VIF. We evaluate the technique that produces the slope in the thickness of VIFs in a monolayer of 600 nm with a LMEs Surface Profiler. The VIFs characterized optically with spectrophotometers, can present an optically active area scanning 120,5 nm of the electromagnetic spectrum between channels 475,5 nm to 596 nm, belonging to 17,3 mm extension of VIF. FIV is an optical device designed with wedge-shaped thickness resulting in the linear transmittance for the spectral response with a 6,97 nm/mm in extension rate. It was proposed that VIFs characterized together with PD of a PDA, diffuser and lens form a detector module connected to a set of pre-processing and data collection (electronic module) thus forming the parameterized MSSR. The proposed MSSR was assessed using the VIF02 which operates a range of optically active (600 nm to 715 nm), a PDA model TSL1401 with PD 128 and Arduino UNO microcontroller to manage the detection. The results indicate that the instrument is equivalent to other reference spectrophotometer measurements, when measuring a monochromatic beam at 655,4 nm, but with narrower 0,13 nm resolution by channel. It was also pointed out the necessity of dedicated instrumentation for optical characterizations of other VIF MSSR detector assembly and the calibration.

Neste trabalho são apresentados os resultados do estudo e desenvolvimento dos parâmetros de projeto de um radiômetro solar multiespectral (RSME), baseado em Filtros de Interferência Variável (FIV) de banda-passante que incorpora uma camada ressoante de Fabry-Perot, inclinada em forma de cunha, sintonizável dentro da área opticamente ativa do FIV, aplicável ao sensoriamento ambiental e de aerossóis. Foi apresentada a teoria proposta para a simulação, projeto e deposição pelo método interativo (simulações associada às avaliações de deposições). O FIV foi parametrizado para o RSME, mas pode atender outras aplicações em sensores multicanais e multiespectrais. A construção dos FIV exigiu estudos e adaptações das técnicas clássicas de deposição de filmes finos e de microeletrônica, foi utilizada a PVD/E-Beam. É apresentado um estudo e o emprego de simulações matemáticas e softwares, aplicáveis a FI convencionais correlatas aos FIVs. Estes softwares foram aplicados e avaliados em relação ao projeto dos FIV. Avaliamos a técnica empregada que produz a inclinação na espessura dos FIVs em uma monocamada de 600 nm com um Perfilômetro do LME. Os FIVs caracterizados opticamente com espectrofotômetros, apresentam uma área opticamente ativa de varredura de 120,5 nm no espectro eletromagnético, entre os canais 475,5 nm a 596 nm, pertencentes a 17,3 mm de extensão do FIV. O FIV é um dispositivo óptico projetado com espessura em cunha provocando a resposta espectral linear para a transmitância, com uma taxa de 6,97 nm/mm na sua extensão. Foi proposto que os FIVs caracterizados em conjunto com PD de um PDA, difusor e lente, formem um conjunto detector conectado a um módulo de pré-processamento e coleta de dados (módulo eletrônico) formando assim o RSME parametrizado. O RSME proposto foi avaliado utilizando o FIV02 que opera numa faixa opticamente ativa entre (600 nm a 715 nm), um PDA modelo TSL1401 com 128 PD e um microcontrolador Arduino UNO para o gerenciamento da detecção. Os resultados apontam que o instrumento faz medições equivalentes a outro espectrofotômetro de referência quando medindo um feixe monocromático em 655,4 nm, mas com resolução mais estreita de 0,13 nm por canal. Foi apontada também a necessidade de instrumentação dedicada para outras caracterizações ópticas dos FIV, do conjunto detector do RSME e para a sua calibração. / This paper presents the results of the study and development of the design parameters of a Multi-Spectral Solar Radiometer (MSSR), based on Variable Interference Filter (VIF) pass-bad which incorporates a resonant layer Fabry-Perot inclined in form wedge, tunable within the optically active area of VIF, applicable to enviro nmental sensing and aerosols. The theory proposed was presented for the simulation, design and deposition by interactive method (associated with reviews of depositions simulations). The VIF was parameterized for the MSSR, but can serve other applications in multi-channel and multispectral sensors. The construction of VIF required studies and adaptations of the classic techniques of thin film deposition and microelectronic, was used the PVD / E-Beam. A study and the use of mathematical and simulation software, related to VIFs applicable to conventional IF appears. This software were applied and assessed in relation to the design of VIF. We evaluate the technique that produces the slope in the thickness of VIFs in a monolayer of 600 nm with a LMEs Surface Profiler. The VIFs characterized optically with spectrophotometers, can present an optically active area scanning 120,5 nm of the electromagnetic spectrum between channels 475,5 nm to 596 nm, belonging to 17,3 mm extension of VIF. FIV is an optical device designed with wedge-shaped thickness resulting in the linear transmittance for the spectral response with a 6,97 nm/mm in extension rate. It was proposed that VIFs characterized together with PD of a PDA, diffuser and lens form a detector module connected to a set of pre-processing and data collection (electronic module) thus forming the parameterized MSSR. The proposed MSSR was assessed using the VIF02 which operates a range of optically active (600 nm to 715 nm), a PDA model TSL1401 with PD 128 and Arduino UNO microcontroller to manage the detection. The results indicate that the instrument is equivalent to other reference spectrophotometer measurements, when measuring a monochromatic beam at 655,4 nm, but with narrower 0,13 nm resolution by channel. It was also pointed out the necessity of dedicated instrumentation for optical characterizations of other VIF MSSR detector assembly and the calibration.

Η εφαρμογή της μικροκυματικής ραδιομετρίας έχει επεκταθεί στο χώρο της ιατρικής, καθότι τα τελευταία χρόνια γίνονται έρευνες με σκοπό την εκμετάλλευση των ιδιοτήτων της μεθόδου στη διαγνωστική αλλά και στη θεραπευτική ιατρική. Στα πλαίσια μιας διδακτορικής διατριβής που εκπονήθηκε στο Εργαστήριο Μικροκυμάτων και Οπτικών Ινών (ΕΜΟΙ) της σχολής Ηλεκτρολόγων Μηχανικών και Μηχανικών Υπολογιστών του Εθνικού Μετσόβιου Πολυτεχνείου και ολοκληρώθηκε το 2003, κατασκευάστηκε ένα τρισδιάστατο σύστημα παθητικής μικροκυματικής ραδιομετρικής απεικόνισης (ΜiRaIS) για διαγνωστικές εφαρμογές εγκεφάλου. Στη συγκεκριμένη μέθοδο χρησιμοποιείται μια αγώγιμη ελλειψοειδής κοιλότητα, ώστε να επιτευχθεί μέγιστη συγκέντρωση και εστίαση ακτινοβολίας που εκπέμπει το φυσικό σώμα ενδιαφέροντος, σε συνδυασμό με ραδιομετρικούς δέκτες ολικής ισχύος και ομοιοκατευθυντικές κεραίες λήψης στο φάσμα συχνοτήτων 1-4GHz. Στην παρούσα διπλωματική εργασία γίνεται θεωρητική και πειραματική μελέτη ενός νέου μικροκυματικού ραδιομετρικού συστήματος. Η αρχή λειτουργίας του είναι όμοια με αυτήν του MiRaIS, δηλαδή πλήρως παθητική και μη επεμβατική. Η βασική διαφορά του είναι ότι χρησιμοποιεί μια τροποποιημένη ελλειψοειδή κοιλότητα η οποία βελτιώνει την εργονομία του συστήματος διατηρώντας παράλληλα της ιδιότητες εστίασης του πρωτότυπου ελλειψοειδούς. Στη θεωρητική μελέτη, με τη βοήθεια του λογισμικού High Frequency Structure Simulation (HFSS) που βασίζεται στη μέθοδο των πεπερασμένων στοιχείων, αναλύονται δυο μέθοδοι για τη βελτίωση των ιδιοτήτων εστίασης του συστήματος (πχ. βάθος διείσδυσης της ακτινοβολίας, χωρική διακριτική ικανότητα) με τη χρήση διηλεκτρικών υλικών και υλικών με αρνητικό δείκτη διάθλασης (Left Handed Materials-LHM). Στην πρώτη περίπτωση, τα υλικά αυτά χρησιμοποιούνται ως στρώματα προσαρμογής που τοποθετούνται γύρω από το μοντέλο κεφαλιού για την επίτευξη βηματικής αλλαγής του δείκτη διάθλασης στη διεπιφάνεια αέρα-μοντέλου ανθρώπινου κεφαλιού. Στη δεύτερη προσέγγιση του προβλήματος, χρησιμοποιείται μια σφαίρα από διηλεκτρικό σε συνδυασμό με ένα στρώμα προσαρμογής από LHM για την καλύτερη εστίαση του συστήματος. Προς την ίδια κατεύθυνση, στη δεύτερη αυτή περίπτωση χρησιμοποιείται επίσης ένας ελλειψοειδής ανακλαστήρας μειωμένου όγκου το εσωτερικό του οποίου είναι γεμάτο με διηλεκτρικό με χαμηλές απώλειες, με τα αποτελέσματα να δείχνουν σημαντική βελτίωση της χωρικής διακριτικής ικανότητας του συστήματος. Η πειραματική διάταξη τοποθετήθηκε σε ανηχοϊκό θάλαμο όπου και πραγματοποιήθηκαν όλες οι μετρήσεις. Στις πειραματικές διαδικασίες που ακολουθήθηκαν, χρησιμοποιήθηκαν ομοιώματα νερού (phantoms) σε διάφορα μεγέθη και θερμοκρασίες για την επιβεβαίωση της διατήρησης των ιδιοτήτων εστίασης του νέου ελλειψοειδούς ανακλαστήρα. Επίσης, διενεργήθηκαν μετρήσεις με στρώματα προσαρμογής φτιαγμένα από διηλεκτρικά υλικά, τα οποία τοποθετούνταν γύρω από το αντικείμενο ενδιαφέροντος, για την πληρέστερη κατανόηση της επίδρασης των υλικών αυτών στις ιδιότητες εστίασης του συστήματος και για την επιβεβαίωση των αντίστοιχων θεωρητικών αποτελεσμάτων. / In the framework of a PhD thesis which was completed in the Laboratory of Microwaves and Fiber Optics (MFOL), School of Electrical and Computer Engineering, National Technical University of Athens (NTUA) in 2003, a Three Dimensional Passive Microwave Radiometry Imaging System (MiRaIS) was designed and constructed for brain diagnostic applications. The novelty of the proposed methodology consists in the use of a conductive ellipsoidal cavity to achieve maximum peak of radiation pattern in order to measure the intensity of the microwave energy, radiated by the medium of interest, by using two microwave total power radiometers and relevant non-contacting antennas within the range of 1-4GHz. In the present thesis, a new microwave radiometry system is theoretically and experimentally studied. It has the same operation principal with MiRaIS as it operates in an entirely non-invasive and passive manner. Its main difference is that it comprises a modified ellipsoidal cavity which improves the system’s ergonomy preserving the focusing properties of the original cavity. In the theoretical study, two methods for the improvement of the system’s focusing properties (e.g. penetration depth of the electromagnetic field, spatial sensitivity) using dielectric materials and left-handed materials (LHM) are tested with the use of a commercially available software tool, High Frequency Structure Simulation (HFSS). In the first case, those materials are used as matching layers placed around the human head model for the achievement of stepped change of the refraction index on the air-human head model interface. On the second approach, a sphere made of dielectric material is used in conjunction with a LHM matching layer in order to improve the system’s spatial sensitivity. Towards the same direction, a reduced volume ellipsoidal cavity filled with low loss dielectric material is used showing promising results. The experiments were performed inside an anechoic chamber providing maximum accuracy avoiding any external intergerence. In the experimental procedures that were performed, water phantoms of several sizes and temperatures were used in order to confirm that the new ellipsoidal beamformer maintains the focusing properties of the original one. Also, measurements were conducted using dielectric matching layers, placed around the medium of interest, in order to fully understand the effect of those materials in the system’s focusing properties as well as confirm the relative theoretical results.

Καθώς η εξέλιξη της βιοϊατρικής επιστήμης και τεχνολογίας είναι συνεχής και ραγδαία, η έρευνα επικεντρώνεται τόσο στη βελτίωση των κλινικών τεχνικών όσο και στην ανάπτυξη νέων με κυριότερο σκοπό την ακριβέστερη και ασφαλέστερη διάγνωση και θεραπεία. Στην παρούσα διπλωματική εργασία, μελετάται η χρήση δύο περιοχών του φάσματος, των μικροκυματικών και των ηχητικών συχνοτήτων για διαγνωστικές λειτουργικές εφαρμογές εγκεφάλου. Παρόλο που η χρήση των υπερήχων έχει αξιοποιηθεί στην κλινική εφαρμογή, οι αναφορές για τη χρήση των ηχητικών κυμάτων στις βιοιατρικές εφαρμογές είναι περιορισμένες στη διεθνή βιβλιογραφία. Στην παρούσα διπλωματική εργασία μελετάται η ανάπτυξη ενός συστήματος για διαγνωστικές εφαρμογές εγκεφάλου στις ηχητικές συχνότητες. Στα δύο πρώτα κεφάλαια περιγράφονται οι βασικές αρχές που διέπουν την επιστήμη του ήχου (ακουστική) αλλά και οι φυσικές αρχές αλληλεπίδρασης των ηχητικών κυμάτων με τους βιολογικούς ιστούς (δημιουργία και εξέλιξη των φυσικών φαινομένων ανάκλασης, διάθλασης, μετάδοσης και απορρόφησης της ηχητικής δέσμης). Πιο συγκεκριμένα μοντελοποιείται και μελετάται θεωρητικά το πρόβλημα της αλληλεπίδρασης των ηχητικών κυμάτων με τον ανθρώπινο εγκέφαλο. Στο τρίτο κεφάλαιο παρατίθεται η θεωρητική ανάλυση και οι βασικές αρχές της προτεινόμενης μεθόδου για μέτρηση της εγκεφαλικής δραστηριότητας στις ηχητικές συχνότητες καθώς και τα βασικά στοιχεία της πρακτικής της υλοποίησης που περιλαμβάνουν ανάλυση του πιεζοηλεκτρικού φαινομένου και των αντίστοιχων μετατροπέων καθώς και το αντίστοιχο σύστημα λήψης ηχητικών σημάτων. Τα μικροκύματα έχουν χρησιμοποιηθεί σε πλήθος διαγνωστικών και θεραπευτικών τεχνικών τόσο σε επίπεδο έρευνας όσο και στην κλινική πράξη. Στην παρούσα εργασία πραγματοποιείται θεωρητική μελέτη δύο πολυσυχνοτικών κυρτών προσαρμόσιμων μικροταινιακών τυπωμένων κεραιών για χρήση τους με συστήματα ευαίσθητων δεκτών μικροκυματικής ραδιομετρίας. Στο κεφάλαιο 4 περιγράφονται η βασική τεχνολογία και οι βασικές αρχές λειτουργίας της παθητικής μεθόδου διάγνωσης με μικροκύματα, της μικροκυματικής ραδιομετρίας. Οι προτεινόμενες κυρτές κεραίες μοντελοποιήθηκαν (κεφάλαιο 5) και μελετήθηκαν με τη βοήθεια του ηλεκτρομαγνητικού προσομοιωτικού λογισμικού πακέτου HFSS που χρησιμοποιεί τη μέθοδο των πεπερασμένων στοιχείων. Παρουσιάζονται αναλυτικά οι ιδιότητες εστίασης των κεραιων αυτών σε δύο διαφορετικά μοντέλα κεφαλιού στος εύρος συχνοτήτων 2 – 3.5 GHz. / As the evolution in the field of biomedical science and technology is continuous, the research focuses mainly on the improvement of existent clinical techniques and the development of new ones, aiming to the most accurate and safe diagnosis and treatment. In the present thesis, the usage of two frequency bands is investigated, the microwave and sound frequencies for diagnostic functional brain applications. Despite the fact that ultrasounds have been utilized in clinical practice, the references regarding the application of sound frequencies in medical diagnosis are restrained in international literature. In the present thesis the development of a system for diagnostic brain applications operating at sound frequencies is studied. In the first two chapters the basic principles of acoustics and the physical principles of the interaction of sound waves with biological tissue (including physical phenomena of reflection, diffraction, transmission and absorption of sound) are described. More specifically, the problem of the interaction of sound waves with the human brain tissues is theoretically modeled and studied. In the third chapter theoretical analysis and basic principles of the suggested method are given together with the basic points of its practical implementation that include analysis of the piezoelectric phenomenon, the respective piezoelectric transducers and sound signal receiver. Microwaves have been used in many diagnostic and therapeutic techniques both at research level and in clinical practice. Herein, a theoretical study of two multi-frequency conformal microstrip patch antennas is performed, in order to use them in conjunction with sensitive microwave radiometry receivers. In chapter 4 the basic technology and the basic operation principles of the passive diagnostic method with microwaves (microwave radiometry) are described. The suggested conformal antennas are modeled (chapter 5) and studied using the electromagnetic simulation tool HFSS that implements the finite element method (FEM). The properties of these antennas and their focusing ability on specific brain areas are presented at 2 – 3.5 GHz in two different head models.

La conduction thermique devient moins efficace à mesure que la taille des struc-tures diminuent en desous du micron, car la diffusion de surface des phononsdevient prédominante et limite plus efficacement les phonons que la diffusionphonon-phonon Umklapp. Des études récentes ont indiqué que les phonon po-laritons de surface (SPhPs), qui sont les ondes électromagnétiques évanescentesgénérées par l’hybridation des phonons optiques et des photons et se propageantà la surface d’une surface diélectrique polaire, pourraient servir de nouveauxvecteurs de chaleur pour améliorer les performances thermiques dans des dis-positifs micro- et nano-métriques. Nous étudions l’état des SPhPs existantdans un film submicronique diélectrique dans une large gamme de fréquences.Le calcul de la conductivité thermique des SPhPs basé sur l’équation de trans-port de Boltzmann (BTE) montre que le flux de chaleur transporté par lesSPhPs est supérieur à celui des phonons. Nous effectuons également une mesurede réflectance thermique dans le domaine temporel (TDTR) de films submi-croniques deSiNet démontrons que la conductivité thermique due aux SPhPsà haute température augmente lorsque l’épaisseur du film dimine. Les résultatsprésentés dans cette thèse ont des applications potentielles dans le domaine dutransfert de chaleur, de la gestion thermique, du rayonnement en champ proche et de la polaritoniques. / Thermal conduction becomes less efficient as structures scale down into submicron sizes since phonon-boundary scattering becomes predominant and impede phonons more efficiently than Umklapp scattering. Recent studies indicated that the surface phonon polaritons (SPhPs), which are the evanescent electromagnetic waves generated by the hybridation of the optical phonons and the photons and propagating at the surface of a polar dielectric material surface, potentially serve as novel heat carriers to enhance the thermal performance in micro- and nanoscale devices. We study the condition of SPhPs existing in a dielectric submicron film with a broad frequency range. The calculaton of SPhPs thermal conductivity based on Boltzmann transport equation (BTE) demonstrates that the heat flux carried by SPhPs exceeds the one carried by phonons. We also conduct a time-domain-thermal-reflectance (TDTR) measurement of $SiN$ submicron films and demonstrate that the thermal conductivity due to the SPhPs at high temperatures increases by decreasing the film thickness. The results presented in this thesis have potential applications in the field of heat transfer, thermal management, near-field radiation and polaritonics.

This thesis deals with the diagnosis of a residential building from the late nineteen twenties for the needs of reconstruction. The methods generally used in the diagnosis of structures are briefly described in the theoretical part. More deeply this section describes the methods that were used during this particular research. The practical part deals with the diagnosis of the object itself. The first section describes the layout of the villa, its design solution, its faults and defects detected during the inspection. The next section deals with evaluating the current state of construction materials. Static reports of several structural parts were calculated in the last section.

This thesis treats static and dynamic surface characterization using radiometric and Fourier optical methods. A Fourier optical method has been developed for real time image processing in paper production and printing applications. It has been shown that the method can be used to measure crepe frequency, an important parameter in tissue paper production, as well as to monitor the wire mark pattern at paper web velocities of up to 20 m/s. The wire mark pattern has been used to measure dimensional variations across a paper web. These are important for the mechanical properties of paper. Imaging of the moving surfaces onto a spatial light modulator, necessary for Fourier optical analysis of opaque objects, constitutes a motion blur problem. This problem has been solved by means of optical motion compensation using a rotating mirror. A rotating mirror system has also been developed for the inspection of small particles fixed to a rotating sample disc. The optical motion compensation configurations have made exposure times of more than two orders of magnitude longer than the exposure time without compensation possible. A light scattering model for opaque objects, for example coated paper, has also been developed and verified, with a coefficient of determination between theory and measurement ranging from r2=0.84 to r2=0.98, on various paper samples. The light scattering model has been used in the development of an instrument based on the photometric stereo principle. In this instrument the reflectance (or color) and topography of opaque samples are determined from two or more images of the sample illuminated from different directions. The method has been successfully used for studies of the relation between topography and print results in gravure and flexographic printing. Comparisons of surface height profiles measured with the photometric stereo method and profiles obtained with mechanical and optical scanning stylus instruments have shown coefficients of determination of up to r2=0.97. The main advantages of the method are the high speed, the scalability and the ability to obtain reflectance and surface height maps of a surface simultaneously.