With the digital systems moving towards higher frequencies, lower operating voltages and higher power, supplying the required current at the right voltage and at the right time to facilitate timely switching of the CMOS circuits becomes increasingly challenging. The board level power supply cannot meet these requirements directly due to the high inductance of the package interconnections. To overcome this problem, several thin film decoupling capacitors have to be placed on the IC or close to the IC in the package. Two approaches were pursued for high-k thin film decoupling capacitors. 1) Low cost sol-gel based thin film capacitors on organic board compatible Cu-foils 2) RF-sputtered thin film capacitors on silicon substrate for silicon compatible processes While sol-gel provides cost effective technology, sputtered ferroelectric devices are more compatible from manufacturing stand point with the existing technology. Nano-crystalline barium titanate and barium strontium titanate film capacitor devices were fabricated and characterized for organic and silicon substrates respectively. Sol-gel barium titanate films were fabricated first on a bare Cu-foil and then transferred to organic board through a standard lamination process. With process optimization and film doping, a capacitance density of 3 µF/cm2 was demonstrated with breakdown voltage greater than 12V. Leakage current characteristics, breakdown voltages, and electrical reliability of the devices were significantly improved through doping of the barium titanate films and modified film chemistry. Films and interfaces were characterized with high resolution electron microscopy, SEM, XRD, and DC leakage measurements. RF sputtering was selected for ferroelectric thin film integration on silicon substrate. Barium strontium titanate (BST) films were deposited on various electrodes sputtered on silicon substrates. The main focus was to improve interface stabilities for high-k thin films on Si to yield large-area defect-free devices. Effect of bottom electrode selection and barrier layers on device yield and performance were investigated carefully. High yield and high device performance was observed for certain electrode and barrier layer combination. A capacitance density up to 1 µF/cm2 was demonstrated with a breakdown voltage above 15 V on large area, 7 mm2, devices. These two techniques can potentially meet mid-high frequency future decoupling requirements.

Ο Επαγωγικός Λογικός Προγραμματισμός (Inductive Logic Programming ή, σε συντομογραφία ILP) είναι ο ερευνητικός τομέας της Τεχνητής Νοημοσύνης (Artificial Intelligence) που δραστηριοποιείται στη τομή των γνωστικών περιοχών της Μάθησης Μηχανής (Machine Learning) και του Λογικού Προγραμματισμού (Logic Programming).Ο όρος επαγωγικός εκφράζει την ιδέα του συλλογισμού από το επί μέρους στο γενικό. Μέσω της επαγωγικής μάθησης μηχανής ο Επαγωγικός Λογικός Προγραμματισμός επιτυγχάνει το στόχο του που είναι η δημιουργία εργαλείων και η ανάπτυξη τεχνικών για την εξαγωγή υποθέσεων από παρατηρήσεις (παραδείγματα) και η σύνθεση-απόκτηση νέας γνώσης από εμπειρικές παρατηρήσεις. Σε αντίθεση με της περισσότερες άλλες προσεγγίσεις της επαγωγικής μάθησης ο Επαγωγικός Λογικός Προγραμματισμός ενδιαφέρεται για της ιδιότητες του συμπερασμού με κανόνες για την σύγκλιση αλγορίθμων και για την υπολογιστική πολυπλοκότητα των διαδικασιών. Ο Επαγωγικός Λογικός Προγραμματισμός ασχολείται με την ανάπτυξη τεχνικών και εργαλείων για την σχεσιακή ανάλυση δεδομένων. Εφαρμόζεται απευθείας σε δεδομένα πολλαπλών συσχετισμών για την ανακάλυψη προτύπων. Τα πρότυπα που ανακαλύπτονται από τα συστήματα στον Επαγωγικό Λογικό Προγραμματισμό προκύπτουν από κάποιο γνωστό θεωρητικό υπόβαθρο και θετικά και αρνητικά παραδείγματα και εκφράζονται ως λογικά προγράμματα. Ο Επαγωγικός Λογικός Προγραμματισμός έχει χρησιμοποιηθεί εκτεταμένα σε προβλήματα που αφορούν τη μοριακή βιολογία, την βιοχημεία και την χημεία. Ο Επαγωγικός Λογικός Προγραμματισμός διαφοροποιείται από τις άλλες μορφές Μάθησης Μηχανής, αφ’ ενός μεν λόγω της χρήσης μιας εκφραστικής γλώσσας αναπαράστασης και αφ’ ετέρου από τη δυνατότητά του να χρησιμοποιεί τη γνώση υποβάθρου. Έχουν αναπτυχθεί διάφορες μηχανισμούς υλοποίησης του ILP, εκ των οποίων η πιο πρόσφατη είναι η Progol, που βασίζεται σε ένα διερμηνέα της Prolog ο οποίος συνοδεύεται από έναν αλγόριθμο Αντίστροφης Συνεπαγωγής (Inverse Entailment). Η Progol κατασκευάζει νέες προτάσεις με τη γενίκευση των παραδειγμάτων που περιέχονται στη βάση δεδομένων που της δίνεται. Η θεωρία του Επαγωγικού Λογικού Προγραμματισμού εγγυάται ότι η Progol θα διεξάγει μια αποδεκτή αναζήτηση στο διάστημα των γενικεύσεων, βρίσκοντας το ελάχιστο σύνολο προτάσεων, από το οποίο όλα τα παραδείγματα μπορούν να προκύψουν. Σε αυτή την εργασία θα αναπτυχθούν αναλυτικά η θεωρία και οι κανόνες του Επαγωγικού Λογικού Προγραμματισμού, τα είδη των προβλημάτων που επιλύονται μέσω του Επαγωγικού Λογικού Προγραμματισμού, οι μέθοδοι που ακολουθούνται καθώς και ο τρόπος με τον οποίο αναπτύσσονται οι εφαρμογές του Επαγωγικού Λογικού Προγραμματισμού. Θα δοθούν επίσης παραδείγματα κατάλληλα για την κατανόηση των γνώσεων αυτών από ένα ακροατήριο που διαθέτει βασικές γνώσεις Λογικής και Λογικού Προγραμματισμού. / Inductive Logic Programming is a research area of Artificial Intelligence that operates in the intersection of cognitive areas of Machine Learning and Logic Programming. Through inductive machine learning, Inductive Logic Programming‟s objective is creating tools and developing techniques to extract new knowledge composing a background one and empirical observations (examples). Some methods are employed, the best known of which is the reverse implication, the reverse resolution and the inverse implication. Based on Inductive Logic Programming, some systems have been developed for knowledge production. The most widely used system is Progol, which uses an input of examples and background knowledge, whichε is stated in a kind of grammar compatible to that the programming language Prolog, and generates procedures in the same language that illustrate these examples. Other systems are FOIL, MOBAL, GOLEM and LINUS. There is also Cigol which is a programming language based on the theory of Inductive Logic Programming. These systems are used in many applications. The most important is the area of pharmacology, such as predictive toxicology, the provision of rheumatic disease and the design of drugs for Alzheimer's. Applications can also be found in programming, linguistics and games like chess.

Made available in DSpace on 2014-06-11T19:27:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2011Bitstream added on 2014-06-13T19:35:03Z : No. of bitstreams: 1 munekata_rm_me_ilha.pdf: 4705141 bytes, checksum: 56254cadfa4c90cb796f3b90671140ee (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho estudou a influência da energia do pulso de soldagem, no caso processo laser de Nd:YAG operando no modo pulsado, na soldagem de duas lâminas finas com 100 μm de Hastelloy C-276, utilizado no revestimento de sensores que trabalham em ambiente corrosivo da indústria sucroalcooleira, química petroquímica e alimentícia. Utilizou-se energia de pulso de 1,0 Joule a 2,25 Joules, com incremento de 0,25 Joules com a velocidade de soldagem de (ν) taxa de repetição (Rr) fixas de 525mm/min e 39Hz respectivamente e largura temporal de 4 ms. As soldas foram realizadas com proteção gasosa de argônio. Foram realizadas análises macrográficas e micrográficas das juntas soldadas, através de secções transversais das mesmas e ensaios de microdureza Vickers e ensaio de tração. Os resultados obtidos mostraram que o controle da energia do pulso, em processo de soldagem por laser de lâminas finas é de fundamental importância para a geração de juntas soldadas livres de descontinuidades. Os parâmetros geométricos da junta soldada, tais como largura do cordão, largura de união e profundidade do cordão, aumentaram em função do aumento da energia do pulso. O processo mostrou-se muito sensível à formação de porosidade e à presença de gap entre as lâminas / This work measured experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser welding to examine the influence of the pulse energy in two thin foil welding with 100 μm thickness, employed to cover sensors that work in corrosive environment of the sugar and alcohol industry,chemical petrochemistry and nourishing. The pulse energy was varied from 1,0 to 2,25 J at an increment of 0.25 J and an increment of 0.25 Joules with a welding speed and(ν) repetition rate (Rr) fixed 525mm/min and 39Hz respectively and 4 ms pulse duration. The specimens were laser-welded in an argon atmosphere. The welds were analyzed by macroscopic and microscopic observations using optical microscopy and micro hardness and tensile test. The results indicated that pulse energy control, in laser welding of thin foils, is of considerable importance for weld quality since it can generate discontinuities free weld joints. The geometric parameters of the welded joints like bead width, connection width and bead depth increased with the pulse energy increasing. The process showed very sensitive to porosity formation and gap between couple

Des études internes à Liebherr-Aerospace France, concernant la conception de nouveaux compresseurs lubrifiés par gaz réfrigérant, ont montré que dans des conditions de fonctionnement spécifiques, un mélange de vapeur et de liquide apparaît au sein du compresseur, au lieu d'une phase vapeur seule. De ce fait, le comportement des paliers à feuilles lubrifiés au gaz réfrigérant est étudié, y compris la possibilité d'un écoulement diphasique du lubrifiant. L'étude porte sur le comportement du lubrifiant uniquement, dans des conditions de fonctionnement qui sont celles des paliers à feuilles. L'approche Thermo-Hydrodynamique décrit les caractéristiques du lubrifiant telles que la pression, la densité, la viscosité et la température. Dans ce modèle, une équation de Reynolds généralisée pour écoulement turbulent, une équation d'état non-linéaire pour écoulement diphasique et une équation de l'énergie tridimensionnelle pour film-mince et écoulement turbulent sont utilisées. Les paramètres globaux du palier sont calculés en régime permanent. / Internal experiments at Liebherr-Aerospace FRANCE on new refrigerant-lubricated compressor designs have shown that under specific operating conditions, a mixture of vapor and liquid appears in the compressor, instead of a single-phase vapor flow. Therefore, refrigerant-lubricated foil bearings behavior is studied, including the likelihood of two-phase flow in the lubricant. We focus on the lubricant behavior only, in the operating conditions of foil bearings. The Thermo-Hydrodynamic approach describes lubricant characteristics such as pressure, density, viscosity, and temperature. It involves the use of a generalized Reynolds equation for turbulent flow, a nonlinear cubic equation of state for two-phase flow and a 3D turbulent thin-film energy equation. Journal bearing global parameters are calculated for steady-state conditions.

In the initial stage, the sample preparation was done by using the techniques of Anodic etching and anodic forming processes where a repeated trial and error method of sample preparation headed towards making out a suitable sample set for characterization. After this step, the set of 2 different industrial samples were introduced and anodic oxide forming process was carried out in different electrolytes.    In the sample preparations, 4 different electrolytes were used 15% wt. Ammonium Adiphate, 1.5% wt. Ammonium Phosphate, 7% wt. Boric acid and 15% Penta Borate at different stages for performing the anodic oxide forming process. Minimum forming voltages of 20V to a maximum of 100V was employed in the sample preparation and to overcome the waiting time in forming the etched samples a higher current of 0.5A was used.   After the samples preparation, Electrochemical Impedance spectroscopy was used as a tool for characterising the various groups of samples and for observing the micro structures of various samples, they were fractured and the observed on the cross section by SEM.   After the analysis of the etched samples was made, an attempt to compare the results of the data of these samples to that of the 2 set of industrial samples was made and found that the resultant data wasn’t stable enough to characterize since huge scattering were occurring and whereby the simulation of the CPE circuit for the chosen circuit in the analysis was not possible.   Under the analysis, a randomly chosen industrial sample was also used and the resultant data was utilised in understanding the response of the system to different electrolytes. / Sammanfattning   Avhandlingsarbetet har genomförts på KEMET AB i samarbete med yttekniklaboratoriet vid JTH i syfte att karakterisera den etsade anodiska aluminiumfolien som grundprov med anodisering och etsning för ytbehandling.   I inledningsskedet gjordes provberedningen med användning av teknikerna för anodisk etsning och anodbildande processer där en upprepad provnings- och felmetod för provberedning ledde ut mot att utarbeta en lämplig provuppsättning med avseende på karakterisering. Efter detta steg infördes uppsättningen av 2 olika industriella prover och anodoxidbildande process utfördes i olika elektrolyter.   I provpreparaten användes 4 olika elektrolyter 15 % vikt Ammoniumadiphat, 1,5 vikt% Ammoniumfosfat, 7 vikt% Borsyra och 15 % Penta-borat vid olika steg för utförande av anodoxidbildningsförfarandet. Minimala formningsspänningar på 20V till ett maximum av 100V användes i provframställningen och för att övervinna väntetiden vid bildning av de etsade proven användes en högre ström av 0,5A.   Efter provberedningen användes elektrokemisk impedansspektroskopi som ett verktyg för att karakterisera de olika grupperna av prover och för att observera mikrostrukturerna i olika prover, de bröts och de observerades i tvärsnittet av SEM.   Efter att analysen av de etsade proverna gjordes ett försök att jämföra resultaten av data från dessa prover till den för de två uppsättningarna av industriella prover. Det är konstaterat att de resulterande data inte var stabila nog att karakterisera eftersom stor spridning inträffade och varigenom simuleringen av CPE-kretsen för den valda kretsen i analysen inte var möjlig.   Under analysen användes också ett slumpmässigt valt industriellt prov och de resulterande data användes för att förstå systemets respons till olika elektrolyter.

Nickel based superalloys are currently being investigated for high temperature applications in advanced steam power plant operating at temperatures of 700˚C and above. Three nickel-based superalloys Inconel 617, Inconel 625 and Nimonic 263 alloys, which are of primary interest for boiler technology components such as furnace walls, superheater tubes, header and steam pipes, etc and for steam turbine technology components such as HP &IP cylinders, rotor forgings, casing and valve chest, blading, etc., have been evaluated for long and short term creep performance. Creep deformation processes occurring at high temperatures and stresses lead to the evolution of microstructures in the form of precipitation, precipitate coarsening and recovery effects. The deterioration in mechanical properties as a result of this microstructural change has been evaluated by hardness testing. This work discusses the microstructural evolution occurring in alloys in samples that have been creep exposed at a series of temperatures from 650°C to 775°C and for durations from 1000 to 45,000 hours using advanced FEGSEM, TEM, XRD and phase extraction techniques. The fractions and morphology of different phases, their locations during exposure to higher temperatures and probable creep fracture mechanism in these alloys are illustrated and discussed.

This study seeks to understand the interplay of vorticity and elasto-dynamics that forms the basis for a fluttering flag and flapping wing propulsion, and factors that distinguish one from the other. The fluid dynamics is assumed two dimensional and incompressible, and comprises potential and viscous flow simulations. The elastic solid is one dimensional and governed by the Bernoulli-Euler flexure model. The fluid and elastic solid models are coupled using a predictor-corrector algorithm. Flutter of a flag or foil is associated with drag and we show that the pressure on the foil is predominantly circulatory in origin. The circulatory pressure generated on the foil depends primarily on the slope and curvature. The wake vorticity exhibits a wide range of behavior starting from a Kelvin-Helmholtz type instability to a von Kármán wake. Potential flow simulations do not capture the wake accurately both at high and low mass ratios. This is reflected in the flutter boundary and pressure over the foil when compared with viscous flow simulations. Thrust due to heaving of a flexible foil shows maxima at a set of discrete frequencies that coincide with the frequencies at which the flapping velocity of the foil tip is a maximum. The propulsive efficiency shows maxima at a set of discrete frequencies that are close but distinct from the thrust maxima set of frequencies. These discrete frequencies are close to the natural frequencies of vibration of a cantilevered foil vibrating in vacuum. At low frequencies thrust is a consequence of a strong leading edge vortex developed over the foil and it remains attached to the foil as it is convected due to the favorable pressure gradient presented by the time and spatially varying shape of the foil. At moderate and high frequencies of oscillation the pressure, and consequently the thrust, generated by the foil is non-circulatory in origin and they are high where the accelerations of the foil are high. At high frequencies the leading edge vortex is weak. Except in the low frequency range, potential flow simulations qualitatively compares well with viscous flow predictions. We show that thrust and drag on a flexible foil oscillating in a flow is caused by the phase difference between the slope of the foil and the fluid pressure on it. Propulsive efficiency though is governed by the phase difference between foil velocity and fluid pressure and inertia forces. Thus, the interplay of vorticity and elasto-dynamics determine the behavior of a flutter and propulsion of a flexible foil in a fluid flow.

Roofing foils are known for several years as building material for roof hydro insulation but their life service is not yet fully known. This thesis is focused on problematics of life service of roofing foils. In theoretical part there is discribed structure of foils and impacts which assist degradation processes. Practical part modifies the methodology artificial aging which is simulated in QUV tester and Q-SUN XE3 tester lumber-rooms. The thesis is trying reach with the results to natural aging as close as possible. The testing captures attributes which are more prone to degradation.

The thesis describes movement optimization of a linear thermoelectric actuator that is used for operating floor heating valves in modern buildings. Featuring experimental nature, the thesis deals with a problem specified by an industrial company within the following steps; definition of possible solutions based on problem research, experimental verification of selected propositions, the best solution selection resulting from the analysis of executed measurements, final verification with all product versions, benchmarking.

This diploma thesis is mainly focused on the fabrication of graphene layers on the copper foil by the Chemical Vapor Deposition (CVD). For this purpose the high-temperature chamber for the production of the graphene was completed and fully automated. The production of the high area graphene on the copper foil was experimentally achieved. The Raman microscopy and X-ray photoelectron spectroscopy measurements proved that the produced graphene is mostly a monolayer. Graphene layer was transferred on non-conductive substrate.