Au cours de ces travaux de thèse, la mésostructure et le comportement électrique/photoélectrique de mélanges de polymères semi-conducteur et ferroélectrique en films minces ont été étudiés pour des applications en électronique organique. Les propriétés de semi-conduction du P3HT et de ferroélectricité du P(VDF-TrFe) ont été associées au sein d’une même couche active. Il a été observé que le développement d’une morphologie de la couche active en film mince présentant des domaines bi-continus permet de conserver les propriétés intrinsèques des deux matériaux. Des dispositifs de type stockage d’informations ont été réalisés à partir de la couche active composée de 10 % P3HT – 90 % P(VDF-TrFe) et la modulation des propriétés d’injection des dispositifs par le champ ferroélectrique a été étudiée. Des cellules photovoltaïques ont également été réalisées à partir de cette couche active qui présente des propriétés optoélectroniques qui varient selon l’état de polarisation du P(VDF-TrFe). L’influence du champ ferroélectrique sur l’efficacité de la photogénération de charges du P3HT et la modulation du photocourant par l’état de polarisation du P(VDF-TrFe) ont ainsi été déterminées. / In this thesis, the mesostructure and the electric/photoelectric behavior of ferroelectric/semi-conductor polymer blends in thin films have been studied for organic electronic applications. The semi-conductivity property of P3HT was associated with the ferroelectricity of P(VDF-TrFe) in one active layer. It has been observed that the intrinsic properties of both materials remained with the bi-continous morphology of these thin films. Memory devices were fabricated based on the 10 % P3HT – 90 % P(VDF-TrFe) active layer and the modulation of the injection properties by the ferroelectric field has been studied. We have also demonstrated that the P3HT/P(VDF-TrFe) thin films exhibit optoelectronic properties which depend on the polarization state of P(VDF-TrFe). The influence of the ferroelectric field on the photogeneration of charges of P3HT and the variation of the photocurrent with the polarization state of P(VDF-TrFe) were determined.

<p>A method to establish the boundaries of the sensitive volume for a chosen detector to within 50µm (as specified by Elekta Instuments AB) was investigated and is presented in this project. The detector studied was fixed to a positioning system with possibility to move with sub micrometer increments, and scanned in a narrow photon field. The detectors used for the experiment were silicon diodes and a pair of diamond detectors. The silicon diodes showed great promise for future study; two radiotherapy silicon diodes and one electrical component silicon diode were used. The electrical component silicon diode produced a surprisingly sharp dose profile compared with the medical silicon diodes. The diamond detectors gave no stable results at all.</p><p>As a radiation source 60Co proved most feasible, but a diagnostic x-ray source was also tested as well as a 99mTc source. These radiation sources were also examined with a modified Penelope code, i.e. Monte Carlo simulations. What became very obvious with the Monte Carlo simulations was the importance of the line up, which was never satisfactory.</p><p>To limit the sensitive volume of these detectors to within the desired boundaries showed great difficulty and was not achieved in this project.</p>

A method to establish the boundaries of the sensitive volume for a chosen detector to within 50µm (as specified by Elekta Instuments AB) was investigated and is presented in this project. The detector studied was fixed to a positioning system with possibility to move with sub micrometer increments, and scanned in a narrow photon field. The detectors used for the experiment were silicon diodes and a pair of diamond detectors. The silicon diodes showed great promise for future study; two radiotherapy silicon diodes and one electrical component silicon diode were used. The electrical component silicon diode produced a surprisingly sharp dose profile compared with the medical silicon diodes. The diamond detectors gave no stable results at all. As a radiation source 60Co proved most feasible, but a diagnostic x-ray source was also tested as well as a 99mTc source. These radiation sources were also examined with a modified Penelope code, i.e. Monte Carlo simulations. What became very obvious with the Monte Carlo simulations was the importance of the line up, which was never satisfactory. To limit the sensitive volume of these detectors to within the desired boundaries showed great difficulty and was not achieved in this project.

Gabriel Fauré’s Requiem, Op. 48 was an evolving work, which he continued to revise from its inception in 1887 until the published version of 1900. The focus and intent of this paper is to present a detailed analysis of Requiem, Op. 48 as well as historical background to aid conductors in the preparation and performance of this work. Discussions include the history of the requiem mass as a liturgical form, the evolution of Requiem, Op. 48, the John Rutter edition (1984) and his research, and a conductor’s analysis addressing issues of harmony, form, and style.

A program of study has been established for the quantitative study of electrode reactions in solid oxide fuel cells. The initial focus of the program is the mixed conducting cathode material strontium-doped lanthanum manganate (LSM). A formalism was established treating reactions taking place at the gas-exposed surface of mixed conducting electrodes. This formalism was incorporated into a phenomenological model for oxygen reduction in LSM, which treats the phenomenon of sheet resistance. Patterned electrodes were designed that reduce the dimensionality of the appropriate model, and these electrodes were successfully fabricated using DC sputtering and photolithography. A new model for the bulk defect equilibrium in LSM was proposed and shown to be a better fit to nonstoichiometry data at low temperatures. The fitting was carried out with a particle swarm optimizer and a rigorous method for identification. It was shown that a model for the interface structure between LSM and yttria-stabilized zirconia (YSZ) that assumes free oxygen vacancies in YSZ does not accord with experimental observations. Cluster variation method (CVM) was adapted for analysis of the problem, and a new analytical method combining CVM and electrical contributions to the free energy was proposed.

This study armed to develop a biofilter packed only with fern chips for the removal of air-borne low concentration VOCs (volatile organic compounds) emitted from semiconductor manufacturing industries. The fern chip biofilters could avoid the shortcomings of traditional media, such as compaction, drying, and breakdown, which lead to the performance failure of the biofilters. Performance of biofiltration for removal of simulated semiconductor manufacturing emitted gases consisting of IPA (isopropyl alcohol), acetone, HMDS (hexamethylene disilazane), PGME (propylene glycol monomethyl ether), and PGMEA (propylene glycol monomethyl ether acetate) was studied in a pilot-scale biofilter consisted of two columns (40-cmW x 40-cmL x 70-cmH acrylic column) arranged in series. Each column was packed with fern chips to a packing volume of around 56 L (0.40 m¡Ñ0.40 m¡Ñ0.35 mH). A sprinkler was set over the packed fern chips for providing them with water and nutrition solutions. Liquid leached from both layers of chips were collected in the bottom container of the column. The experiment lasted for 182 days which was divided into four phases with varying influent gas flow rates and VOC concentrations. Gas samples collected around 3 times per week from the influent as well a the first and second stage effluents were analyzed for VOC concentrations. On a weekly basis, fern chips sampled from each column were also analyzed for getting pH, moisture, and the absorbed VOC content of the chips. Phase shifted if it obtained a quasi-steady state which was judged by the nearly unchanging VOC removal efficiencies. Operation conditions of an empty bed retention time (EBRT) of 1.50 min and influent VOC concentrations of 159-284 mg/m3 were used in the Phase I experiment which lasted for 15 days. Nutrition of 1.34 g milk powder/m3.d was used in this phase and the conditions gave an average volumetric VOC loading (L) of 15.1 g/m3.h. Effluent VOC concentrations were 3-18 mg/m3 and an average VOC removal of 96% was obtained in this phase. An EBRT of 0.75 min, L of 11.44 g/m3.h, and nutrition of 1.34 g milk powder/m3.d were used in the Phase II experiment. VOCs in the gas could be removed from 90-126 to 1-19.6 mg/m3 and an average efficiency of 94% was obtained. Following Phase II, an average VOC removal of only 48% was obtained with an EBRT of 0.75 min, nutrition of 2.0 g milk powder/m3.d, and L of 22.8 g/m3.h in Phases III experiment during the 56-97th days from the startup time. Additional nitrogen (urea) and phosphorus (potassium dihydrogen phosphate) was added to the media from the 105th day and the VOC removal increased to 80% at the 107th day. An average VOC removal of around 93% was obtained in phase III experiment. The results showed that enough nutrition is essential to the successful performance for the biofiltration process. Phase IV experiment lasted for 59 days with an EBRT of 0.75 min, L of 34.1 g/m3.h, and nutrition of 2.0-6.0 g/m3.d. During the initial period of this phase, media pH dropped from 7.8 to 5.8 due to an excess nitrogen (ammonium chloride) addition as high as 12.35 g N/m3.d which resulted in nitrification reaction in the media. By stopping nitrogen, increasing milk powder dosing, and addition of NaHCO3 at the 140th day, pH restored to 7.5 in the following days. VOC removal increased to an average of 92% in the rest operation days. From the results, it could be proposed that for achieving over 90% of the VOC removal, appropriate operation conditions are media moisture content = 52-65%, media pH = 7-8, influent VOC concentration = 150-450 mg/Am3, EBRT = 0.75 min, and L to the whole media = 11-34 g/m3.h.

This dissertation presents four dual-band printed monopole antennas. There are three printed monopole antennas operating in 2.4 GHz and 5.2/5.8 GHz WLAN bands, and a dual wideband printed monopole operating applies in 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The proposed antennas mainly use two approaches to achieve dual-band and dual wideband operations. The first method uses two different resonant paths in radiating monopole to excite two desired operating frequencies. The proposed configuration using the first method is a printed G-shaped monopole antenna. The second method places the conductor-backed plane on the other side of the radiated monopole to perturb its resonant behaviors for enhancing impedance bandwidth. Three configurations using the second method are proposed. The one with the best wideband performance is a printed rectangular monopole antenna with a trapezoid conductor-backed plane. Measured results for the proposed antennas show satisfactory performances and good agreement with the simulated results.

The theory of local newforms has been studied for the group of \(PGL_n\) and recently \(PGSp_4\) and some other groups of small ranks. In this dissertation, we develop a newform theory for generic supercuspidal representations of \(SO_{2n+1}\) over non-Archimedean local fields with odd characteristic by defining a family of open compact subgroup \(K(p^m)\), \(m \geq 0\) (up to conjugacy) which are analogous to the groups \(\Gamma(p^m)\) in the classical theory of modular forms. We give lower bounds on the dimension of the fixed subspaces of \(K(p^m)\) in terms of the conductor of the generic representation, and give a conjectural description of the space of old forms. These results generalize the known cases for n = 1,2 by Casselman [4] and Roberts and Schmidt [23]. / Mathematics

Solid oxide fuel cells are electrochemical energy conversion devices utilizing solid electrolytes transporting O2- that typically operate in the 800 - 1000 °C temperature range due to the large activation barrier for ionic transport. Reducing electrolyte thickness or increasing ionic conductivity can enable lower temperature operation for both stationary and portable applications. This thesis is focused on the fabrication of free standing ultrathin (<100 nm) oxide membranes of prototypical O2- conducting electrolytes, namely Y2O3-doped ZrO2 and Gd2O3-doped CeO2. Fabrication of such membranes requires an understanding of thin plate mechanics coupled with controllable thin film deposition processes. Integration of free standing membranes into proof-of-concept fuel cell devices necessitates ideal electrode assemblies as well as creative processing schemes to experimentally test devices in a high temperature dual environment chamber. We present a simple elastic model to determine stable buckling configurations for free standing oxide membranes. This guides the experimental methodology for Y2O3-doped ZrO2 film processing, which enables tunable internal stress in the films. Using these criteria, we fabricate robust Y2O3-doped ZrO2 membranes on Si and composite polymeric substrates by semiconductor and micro-machining processes, respectively. Fuel cell devices integrating these membranes with metallic electrodes are demonstrated to operate in the 300 - 500 °C range, exhibiting record performance at such temperatures. A model combining physical transport of electronic carriers in an insulating film and electrochemical aspects of transport is developed to determine the limits of performance enhancement expected via electrolyte thickness reduction. Free standing oxide heterostructures, i.e. electrolyte membrane and oxide electrodes, are demonstrated. Lastly, using Y2O3-doped ZrO2 and Gd2O3-doped CeO2, novel electrolyte fabrication schemes are explored to develop oxide alloys and nanoscale compositionally graded membranes that are thermomechanically robust and provide added interfacial functionality. The work in this thesis advances experimental state-of-the-art with respect to solid oxide fuel cell operation temperature, provides fundamental boundaries expected for ultrathin electrolytes, develops the ability to integrate highly dissimilar material (such as oxide-polymer) heterostructures, and introduces nanoscale compositionally graded electrolyte membranes that can lead to monolithic materials having multiple functionalities. / Engineering and Applied Sciences

Η Υδρογόνωση του Διοξειδίου του Άνθρακα έχει προσελκύσει διεθνώς το ενδιαφέρον της επιστημονικής κοινότητας τόσο ως πιθανή πηγή ανανεώσιμων καυσίμων όσο και ως μέσο μείωσης των εκπομπών του CO2. Στην παρούσα μελέτη χρησιμοποιείται το φαινόμενο της Ηλεκτροχημικής Ενίσχυσης (Η/Ε) της κατάλυσης (EPOC) ή μη- Φαρανταϊκή Ηλεκτροχημική Τροποποίηση της καταλυτικής ενεργότητας (φαινόμενο NEMCA) για την ενίσχυση του ρυθμού και της εκλεκτικότητας της υδρογόνωσης του CO2 σε καταλύτη ρουθηνίου (Ru) υποστηριζόμενου σε πρωτονιακό αγωγό ΒZY. Αρχικά γίνεται μια Εισαγωγή για το Διοξείδιο του Άνθρακα στην οποία και εξηγείται η αναγκαιότητα της περεταίρω μελέτης της αντίδρασης υδρογόνωσης του CO2. Στο Κεφάλαιο 1 γίνεται μια εκτεταμένη αναφορά στους στερεούς ηλεκτρολύτες, με ιδιαίτερη έμφαση στους στερεούς ηλεκτρολύτες πρωτονιακής αγωγιμότητας. Στη συνέχεια στο δεύτερο Κεφάλαιο περιγράφεται το φαινόμενο της Ηλεκτροχημικής Ενίσχυσης της κατάλυσης, γίνεται μια αναφορά των μελετών Η/Ε που έχουν προηγηθεί και παρατίθενται οι κανόνες που διέπουν το συγκεκριμένο φαινόμενο. Στο τρίτο Κεφάλαιο γίνεται βιβλιογραφική ανασκόπηση της συγκεκριμένης αντίδρασης τόσο καταλυτικά όσο και ηλεκτροκαταλυτικά. Στο Κεφάλαιο 4 ακολουθεί η περιγραφή της πειραματικής διάταξης καθώς και ο χαρακτηρισμός του καταλύτη αλλά και τα πειράματα χαρακτηρισμού του ηλεκτρολύτη. Έπειτα, στο Κεφάλαιο 5 παρουσιάζονται τα πειραματικά αποτελέσματα (θερμοκρασιακά, κινητικά, δυναμικής απόκρισης κτλ.), καθώς και μια ποιοτική ανάλυση των παραπάνω αποτελεσμάτων. Και τέλος παρατίθενται τα συνολικά συμπεράσματα της συγκεκριμένης μελέτης. / The Hydrogenation of Carbon Dioxide has attracted international interest in the scientific community as a potential source of renewable fuels and as a means of reducing CO2 emissions. In this study the phenomenon of Electrochemical Promotion of Catalysis (EPOC) or non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) is used in order to enhance the rate and selectivity of this reaction on a Ruthenium (Ru) catalyst deposited on a proton conductor (BZY). The electrochemical promotion of the hydrogenation of CO2 on polycrystalline Ru deposited on a BZY (BaZr0.85Y0.15O3 + 1wt% NiO), a proton conductor in wet atmospheres, was investigated at temperatures 250 to 450oC and atmospheric pressure. Methane and CO were the only detectable products. It was found that the selectivity to CH4 is very significantly enhanced by proton removal from the catalyst via electrochemically controlled spillover of atomic H from the catalyst surface to the proton-conducting support. The apparent Faradaic efficiency of the process takes values up to 500 and depends strongly on the porous Ru catalyst film thickness. The results strongly suggest that the observed strong promotional effect is due to the formation and surface migration of a promoting formate anion generated via potential controlled disproportionation of formic acid adsorbed at the catalyst-proton conducting support interface. This is the first successful electrochemical promotion study of a hydrogenation reaction at temperatures as low as 250oC. There is an up to fourfold enhancement in catalytic rate of CH4 formation with concomitant 50% suppression of the CO formation rate which proceeds in a parallel route.