While a lot of time and resources have been placed into transceiver design, due to the pace of a conventional engineering design process, the design of a power amplifier is often completed using scattered resources; and not always in a methodological manner, and frequently even by an iterative trial and error process. In this thesis, a research question is posed which enables for the investigation of the possibility of streamlining the design flow for power amplifiers. After thorough theoretical investigation of existing power amplifier design methods and modelling, inductors inevitably used in power amplifier design were identified as a major drawback to efficient design, even when examples of inductors are packaged in design HIT-Kits. The main contribution of this research is engineering of an inductor design process, which in-effect contributes towards enhancing conventional power amplifiers. This inductance search algorithm finds the highest quality factor configuration of a single-layer square spiral inductor within certain tolerance using formulae for inductance and inductor parasitics of traditional single-π inductor model. Further contribution of this research is a set of algorithms for the complete design of switch-mode (Class-E and Class-F) power amplifiers and their output matching networks. These algorithms make use of classic deterministic design equations so that values of parasitic components can be calculated given input parameters, including required output power, centre frequency, supply voltage, and choice of class of operation. The hypothesis was satisfied for SiGe BiCMOS S35 process from Austriamicrosystems (AMS). Several metal-3 and thick-metal inductors were designed using the abovementioned algorithm and compared with experimental results provided by AMS. Correspondence was established between designed, experimental and EM simulation results, enabling qualification of inductors other than those with experimental results available from AMS by means of EM simulations with average relative errors of 3.7% for inductors and 21% for the Q factor at its peak frequency. For a wide range of inductors, Q-factors of 10 and more were readily experienced. Furthermore, simulations were performed for number of Class-E and Class-F amplifier configurations with HBTs with ft greater than 60 GHz and total emitter area of 96 μm² as driving transistors to complete the hypothesis testing. For the complete PA system design (including inductors), simulations showed that switch-mode power amplifiers for 50 Ω load at 2.4 GHz centre frequency can be designed using the streamlined method of this research for the output power of about 6 dB less than aimed. This power loss was expected, since it can be attributed to non-ideal properties of the driving transistor and Q-factor limitations of the integrated inductors, assumptions which the computations of the routine were based on. Although these results were obtained for a single micro-process, it was further speculated that outcome of this research has a general contribution, since streamlined method can be used with a much wider range of CMOS and BiCMOS processes, when low-gigahertz operating power amplifiers are needed. This theory was confirmed by means of simulation and fabrication in 180 nm BiCMOS process from IBM, results of which were also presented. The work presented here, was combined with algorithms for SPICE netlist extraction and the spiral inductor layout extraction (CIF and GDSII formats). This secondary research outcome further contributed to the completeness of the design flow. All the above features showed that the routine developed here is substantially better than cut-and-try methods for design of power amplifiers found in the existing body of knowledge. / Thesis (PhD(Eng))--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted

Dans l’âge des objets connectés, circuits conventionnels implémenté sur silicium ne sont pas la seule option pour réaliser des interfaces des capteurs. Dispositifs électroniques implémentés sur substrats souples sont aussi une option intéressante comme interface des capteurs dans notre quotidien, e.g: dans des vêtements, emballages, peau et dedans notre corps humain. Dans cette thèse nous proposons une formalisation de :-La procédure de fabrication de transistors en utilisant des matériaux organiques et flexibles. -La conception de circuits analogiques et numériques en utilisant ces transistors. Les contributions de cette thèse sont :• Optimisation de la procédure de fabrication et caractérisation de 2 technologies : la première fabriqué en utilisant des masques (« shadow masks » en anglais) avec un procès relativement « simple à implémenter ». La deuxième par un procès en utilisant la photolithographie et l’auto alignement. • Modélisation et extraction de paramètres pour prévoir leurs variations dans la conception de circuits.• Customisation des outils CAO « Open Source » VLSI (Alliance ©) pour la conception des circuits et layouts des transistors organiques.• Conception, fabrication et mesure des circuits analogiques (OTAs, comparateurs et convertisseurs analogiques-numériques) et circuits numériques simples (inverseurs, portes logiques, bascules). Ce travail a eu des résultats intéressants et il ouvre un ample spectre d’applications dans l’avenir dans le domaine de l’électronique flexible et organique. / In the era of “Internet of Things”, conventional silicon-based circuits are not the only option to realize sensor interfaces. Electronic devices based on flexible materials are an interesting approach to interface with sensors connected to our everyday life, e.g.: clothes, packages, skin and into the human body. In this thesis, we propose a formalization of the:- Transistor fabrication process using organic and flexible materials.- Analog and digital circuit design using these transistors. The main contribution of this work can be summarized in the following:- Optimization of the fabrication and characterization process of two technologies: the first by shadow masks with an easy-to-fabricate procedure, the second by self-alignment and photolithography.- Modeling and parameter extraction for process variation aware analog design.- Customization of an open source VLSI CAD tools (Alliance©) for circuit design and layout of OTFT.- Design, fabrication and measurement of OTFT analog front-ends (OTAs, Comparators, Analog-to-Digital Converters,…) and basic digital circuits (Inverters, Logic Gates, …).This work achieved very interesting results and it opens a wide scope of future applications in the field of Flexible organic electronics.

L'industrie automobile des systèmes embarqués critiques est confrontée de nos jours à une complexité croissante, tandis que les coûts, les performances en termes d'intelligence, les caractéristiques, les capacités et les délais de commercialisation de leurs produits sont constamment remises en question. Face à cela, l'objectif principal pour les constructeurs et fournisseurs automobiles devient désormais de contrôler la qualité et la fiabilité des systèmes mécatroniques et embarqués. L'existence de normes internationales comme le HIS Automotive SPICE et l’ISO26262 est une contrainte supplémentaire qu'ils doivent prendre en compte s’ils veulent atteindre cet objectif. De plus, assurer la bonne gestion de la sécurité et la qualité du produit ne suffit pas: il est essentiel de veiller à ce que nous produisons un système qui n'est pas seulement sécuritaire et bien, mais aussi que nous produisons le bon système. Cela induit donc une plus grande prise en compte des exigences.Dans cette thèse, nous traitons le challenge du développement des systèmes embarqués automobiles suivant l’Ingénierie Dirigée par les Modèles (IDM) qui répondent aux exigences des utilisateurs et des standards du domaine et qui permettent de maîtriser davantage la qualité des produits développés. Le problème à résoudre a été abordé sur plusieurs phases qui sont ensuite utilisés conjointement. En premier, nous définissons un métamodèle fusionnant les approches orienté qualité produit et qualité processus selon respectivement les normes ISO26262 et SPICE. Puis, dans un but de certification, nous proposons une méthodologie générique basée sur ce métamodèle commun où une évaluation du processus de développement induite par l’HIS standard ainsi qu’une évaluation de la sécurité fonctionnelle induite par l’ISO2626 sont simultanément effectuées. Ce résultat est traduit au travers de la définition d'un framework outillé où nous appliquons la méthode d'évaluation propre au standard SPICE. En deuxième phase, nous définissons un métamodèle pour gérer les actifs de sécurité concernant ces normes automobiles au niveau produit. Ce métamodèle définit comment capturer les exigences et l’architecture d’un système de telle manière qu'ils puissent être traçables entre eux et également traçables depuis des documents de spécifications d’origine. Enfin, une approche à base de modèle où l'interaction des modèles de processus et le produit est géré afin de répondre aux besoins identifiés dans la première phase est développé pour soutenir la gestion de projet. L'approche utilise la modélisation des processus et leur mesure pour améliorer le contrôle et le suivi de projet et de réduire par la même les coûts et les fréquences de replanification.Les avantages de la contribution sont démontrés sur une application pilote automobile, validant ainsi le travail de recherche au vue des faiblesses identifiées préalablement dans le contexte. / The embedded safety-critical systems industry is facing an exponential increase in the complexity and variety of systems and devices while costs, performance in terms of intelligence, features, capacities and time to market are constantly challenged. The main objective for automotive manufacturers and suppliers is now becoming the control of quality and the dependability of embedded and mechatronic systems. The existence of internationally recognized standards such as the Automotive SPICE and ISO26262 is a further constraint that must be managed to meet this objective. Nevertheless, ensuring sound management of safety and viewpoints is insufficient. It is also essential to ensure that we produce a system that is not only compliant and well-defined, but also that we produce the “right” system. Therefore, this leads to greater consideration of the requirements.In this thesis, we address the challenge of development of automotive embedded systems following the model-driven engineering paradigm that meet the user needs and the regulatory constraints of the domain and that further mastered the quality of developed product. We resolve the problem in many steps which are subsequently used jointly. In the first phase, we define a merging approach which embodies a product quality and process quality approaches regarding the ISO26262 and SPICE standards following the model-driven engineering paradigm. Then, in a certification assessment purpose, we propose a generic methodology where an HIS assessment and a functional safety audit is simultaneously performed without altering their original meanings. This commitment results into the definition of a tooled framework where we apply the SPICE assessment method to the common metamodel defined from the merging work. In a second phase, we define a metamodel for manage safety assets regarding these automotive standards at product level. This metamodel defines how the requirements and architecture of a system can be captured in such a way that they can be traceable from each other and from origin specifications documents. Finally, a model-based approach where the interaction of process and product models is managed to address requirements identified in the precedent phases is developed to support project management. The approach uses process modeling and measurement to improve the control and the monitoring of project and to reduce the cost and frequency of re-planning.The benefits of the contribution are demonstrated on an ongoing automotive pilot application, thereby validating the research work against the weaknesses identified prealably in the context.

L'intégration tridimensionnels (3D) ont été couronnés de succès dans les dispositifs traditionnels pour augmenter la densité logique et réduire les distances de mouvement des données. Il résout les limites fondamentales de la mise à l'échelle, par ex. retard croissant dans les interconnexions, les coûts de développement et la variabilité. La plupart des périphériques de mémoire livrés aujourd'hui comportent une forme d'empilage de puce. Mais en raison des limites de dissipation de puissance des circuits intégrés, la fréquence de fonctionnement du MPU d'aujourd'hui a été limitée à quelques GHz. Le but de la thèse est de fournir une méthode de conception globale pour le circuit intégré 3D dans le domaine électrique, thermique, électrothermique et aussi le bruit. À cette fin, la question de recherche est la suivante: Comment réaliser la conception 3D IC, comment gérer VLS 3D IC et comment résoudre les problèmes thermiques dans le CI 3D. Dans ce contexte, les méthodes de simulation pour le substrat et également la connectivité relative (TSV, RDL, Micro strip et circuits intégrés dans le substrat) sont proposées. Afin de satisfaire la demande de recherche, un 3D-TLE et une impédance de substrat sont programmés dans Matlab, qui peut automatiquement extraire de tous les contacts; impédance, de forme arbitraire et de matière arbitraire. L'extracteur est compatible à 100% avec le simulateur de cœur SPICE et vérifié avec les résultats de mesure et les résultats de simulation FEM. Et comme pour une démo, une fréquence de 26 GHz et un filtre RF de bande passante 2GHz sont proposés dans ce travail. Un autre simulateur électrothermique est également programmé et vérifié avec ADS. En tant que solution à la dissipation thermique locale, le caloduc plat est proposé comme composant potentiel. Le modèle caloduc est vérifié avec une simulation FEM. La méthode d'analyse du bruit des substrats et les méthodes de calcul de électriques et thermo-mécanique KOZ sont également présentées. / Three Dimensional (3D) Integration and Packaging has been successful in mainstream devices to increase logic density and to reduce data movement distances. It solves the fundamental limits of scaling e.g. increasing delay in interconnections, development costs and variability. Most memory devices shipped today have some form of chip-stacking involved. But because of the power dissipation limits of ICs, today’s MPU’s operating frequency has been limited to a few GHz. The aim of the thesis is to provide a global design method for the 3D integrated circuit in electrical, thermal, electro-thermal and also noise field. To this end, the research question is as follows: How to realize the 3D IC design, how to manage VLS 3D IC and how to solve the thermal issues in the 3D IC. In this context, the simulation methods for substrate and also relative connectivity (TSV, RDL, Micro strip and circuits embedded into the substrate) are proposed. In order to satisfy the research demand, a 3D-TLE and a substrate impedance are programmed in Matlab, which can automatically extract from any contacts; impedance, of arbitrary shape and arbitrary material. The extractor is 100% compatible with SPICE core simulator, and verified with measurement results and FEM simulation results. And as for a demo, a 26 GHz frequency and 2GHz bandwidth RF filter is propose in this work. Another electro-thermal simulator is also programmed and verified with ADS. As a solution to the local heat dissipation, flat heat pipe (FHP) is proposed as a prospective component. The heat-pipe model is verified with FEM simulation. The substrates noise analysis method and electrical and thermos-mechanical keep-out-of-zone (KOZ) calculation methods are also presented.

Objective: This research aimed at reviewing the information provided by the online drug misuse communities with reference to the available evidence-based literature on the novel psychoactive substances. Methodology: Among hundreds of novel psychoactive substances, four groups (phenethylamines, tryptamines, piperazines and miscellaneous) were selected for the study. Various website drug fora were identified by Google and Yahoo search engines using a set of specific key words. The methods consisted of extracting and analysing qualitative data from the identified website fora. This was also supplemented by critical reviewing the existing evidence-based literature search for each of the selected psychoactive compounds. Results: The combined search results identified 84 unique website fora from which qualitative data were extracted for thirty novel psychoactive substances and organised into technical folders. This data extracted from online communities has thrown some light on factors such as the mode of purchase, subjective experiences, reasons for use, combinations, legislation, mechanisms of action in the CNS, side effects, toxicity and its management. This would enable the clinicians to be obtain full history when assessing and would inform better treatment choices. Conclusions: A range of novel psychoactive substances have been made recently available across the globe. The sale is easily achieved through the Internet. New legislations are made to control some recreational substances whilst newer substances appear. Furthermore, the distributors sell the backlog of products even after controlling of the substance has occured and hence are liable to potentiating criminal investigations. It is here suggested as well that the 'genuinity' of each onlince susbtance is questionable. Evidence-based literature is scant for the vast majority of these substances. Accidental overdoses are common occurences and some of the potential life-threatening clinical situations include sympathomimetic toxidrome and serotonin syndrome. Benzodiazepines appear to help with agitation and neuropsychiatric manifestations. Better levels of international cooperation and rapid share of available information may be needed to tackle the emerging problem of the novel psychoactive substances.

O presente trabalho tem por objetivo o desenvolvimento de um modelo analógico dinâmico do IGBT 2MBI1200U4G-170 para simulação SPICE para a análise de tempos de comutação, perdas e corrente de carga. Este desenvolvimento foi motivado pelo fato de não se dispor de modelos prontos para IGBT para faixas de tensão e corrente na ordem de kV e kA, destinado ao projeto de um conversor CC para controle de motores de tração em locomotivas diesel-elétricas. Como parte do processo se fez uma tentativa de modificação do modelo padrão de IGBT da plataforma Cadence Orcad 16.5, baseada nos trabalho de Hefner, considerada uma forma de modelo físico. Verificou-se que o correto levantamento dos dados para o modelo físico não seria compensatório frente às análises desejadas, o que gerou necessidade por outras formas de modelagem. Decidiu-se por um modelo analógico, obtido com dados do catálogo do componente descritos em tabelas e como fontes de tensão e corrente. Os resultados mostraram-se adequados para projeto térmico, análise de formas de onda e corrente de porta e coletor. A simulação é comparada com curvas da documentação do fabricante e com dados obtidos a partir de testes estáticos em laboratório com duas topologias. Testes foram feitos com tensão de entrada de 74V, 300V, 900V e 1000V, frequências de comutação de 200Hz, 416Hz, 1kHz e 2kHz e correntes de carga de até 1400A. A corrente de carga apresentou diferenças de até 3% com a medida em laboratório e a temperatura divergiu em até 7% com a medida no dissipador do protótipo usado. / This paper presents the design report for an analog IGBT SPICE model, part number 2MBI1200U4G-170. The modeling was perceived as a interesting tool in order to analyze the switching times and losses during the development, not performed at the University, of a chopper DC-DC converter used for current control of traction motors of diesel-electric locomotives. The main motivational factor was that an practical and quick approach was wanted and none standard model was found for the intended IGBT part number. As part of the process, an attempt to modify the standard SPICE model of the Cadence Orcad 16.5, which is a physics model based on Hefner works, was made. It was verified that the correct data collecting for the standard model would not be compensatory, so other modeling techniques were needed. It was decided an analog modeling would be used. The modeling achieved uses no more than the information found on the component datasheet described in tables format, voltage and current sources. The validation was done in two different topologies with load currents up to 1400A, switching frequencies of 200Hz, 416Hz, 1kHz and 2kHz and input voltages of 74V, 300V, 900V and 1000V . Comparatives were done with the vendor catalog and laboratory data. The model is satisfactory for heat, collector and gate currents analysis. The simulation current and temperature results showed differences up to 3% and 7%, respectively, when compared to laboratories measurements.

O presente trabalho tem por objetivo o desenvolvimento de um modelo analógico dinâmico do IGBT 2MBI1200U4G-170 para simulação SPICE para a análise de tempos de comutação, perdas e corrente de carga. Este desenvolvimento foi motivado pelo fato de não se dispor de modelos prontos para IGBT para faixas de tensão e corrente na ordem de kV e kA, destinado ao projeto de um conversor CC para controle de motores de tração em locomotivas diesel-elétricas. Como parte do processo se fez uma tentativa de modificação do modelo padrão de IGBT da plataforma Cadence Orcad 16.5, baseada nos trabalho de Hefner, considerada uma forma de modelo físico. Verificou-se que o correto levantamento dos dados para o modelo físico não seria compensatório frente às análises desejadas, o que gerou necessidade por outras formas de modelagem. Decidiu-se por um modelo analógico, obtido com dados do catálogo do componente descritos em tabelas e como fontes de tensão e corrente. Os resultados mostraram-se adequados para projeto térmico, análise de formas de onda e corrente de porta e coletor. A simulação é comparada com curvas da documentação do fabricante e com dados obtidos a partir de testes estáticos em laboratório com duas topologias. Testes foram feitos com tensão de entrada de 74V, 300V, 900V e 1000V, frequências de comutação de 200Hz, 416Hz, 1kHz e 2kHz e correntes de carga de até 1400A. A corrente de carga apresentou diferenças de até 3% com a medida em laboratório e a temperatura divergiu em até 7% com a medida no dissipador do protótipo usado. / This paper presents the design report for an analog IGBT SPICE model, part number 2MBI1200U4G-170. The modeling was perceived as a interesting tool in order to analyze the switching times and losses during the development, not performed at the University, of a chopper DC-DC converter used for current control of traction motors of diesel-electric locomotives. The main motivational factor was that an practical and quick approach was wanted and none standard model was found for the intended IGBT part number. As part of the process, an attempt to modify the standard SPICE model of the Cadence Orcad 16.5, which is a physics model based on Hefner works, was made. It was verified that the correct data collecting for the standard model would not be compensatory, so other modeling techniques were needed. It was decided an analog modeling would be used. The modeling achieved uses no more than the information found on the component datasheet described in tables format, voltage and current sources. The validation was done in two different topologies with load currents up to 1400A, switching frequencies of 200Hz, 416Hz, 1kHz and 2kHz and input voltages of 74V, 300V, 900V and 1000V . Comparatives were done with the vendor catalog and laboratory data. The model is satisfactory for heat, collector and gate currents analysis. The simulation current and temperature results showed differences up to 3% and 7%, respectively, when compared to laboratories measurements.

Cette thèse s’inscrit dans le domaine de la modélisation des circuits analogiques et mixtes.Le travail part d’une problématique industrielle concernant les circuits électroniques utilisés dansles systèmes de forage pétrolier pour des besoins d’instrumentation et mesures. Ce travail de recherche concerne les circuits du front-end analogique que nous trouvons dans cette application industrielle. Nous examinons et nous essayons de trouver des modèles pour décrire l’effet des hautes températures sur les circuits électroniques dans un forage pétrolier. Ces circuits font partie des circuits industriels conventionnels. Ils ont généralement une température maximale de fonctionnement qui ne dépasse pas 125°C. Même si la température modifie le comportement de ces circuits, il existe des techniques d’adaptation qui permettent de compenser l’effet de la température sur ces circuits. Cependant, pour bien réussir la phase de la conception, il faut d’abord bien caractériser le comportement des différents circuits industriels utilisés en haute température. Il faut également trouver des modèles exacts qui décrivent le comportement de ces circuits en haute température. Or nous savons que la majorité des circuits industriels analogiques et mixtes sont décrits par des modèles de type SPICE. Par un choix de l’entreprise Schlumberger, notre partenaire industriel qui a financé ce travail, nous nous sommes intéressés dans notre étude à un composantspécifique présent dans la majorité des circuits analogiques et mixtes d’instrumentation :l’amplificateur opérationnel (l’AOP).Le travail commence par une étude des spécifications du circuit ainsi que le modèle SPICE.Une étude de la structure de ce modèle et sa simulation ont montré la non-précision du modèle audelàde 125°C. L’étude de validité du modèle a concerné le paramètre de la tension de décalage etle paramètre taux de rejection du mode commun. Nous avons interprété la différence des résultatsentre les mesures et la simulation de la tension de décalage. Nous avons constaté la limitation quereprésente l’approche structurelle par modélisation SPICE. Pour cette raison, nous avonssélectionné l’approche de modélisation comportementale pour les différents avantages qu’elleprésente. Ces avantages répondent à nos besoins et conviennent les mesures qui ont été effectuées.Nous avons sélectionné le langage VHDL-AMS et l’environnement Cadence ADVanceMS. Pourdéveloppé les modèles, nous avons alors énuméré les différents paramètres de performance d’unAOP. Nous avons validé la représentation de chaque paramètre par un circuit de test approprié.Dans un deuxième temps, nous avons approximé la variation de ces paramètres en température pardes équations polynomiales et exponentielles pour développer le modèle précis en HT. Le modèlea été validé par un circuit de test similaire au circuit expérimental. De bons résultats ont ététrouvés. L’erreur moyenne entre simulation VHDL-AMS et mesures n’a pas dépassé 3,11%. Dansle denier chapitre, nous avons simulé des circuits d’une chaine d’instrumentation. Nous avonssimulé l’effet de la température sur un capteur piézo-résistif (pont de Wheatstone). Trois architectures d’un amplificateur d’instrumentation ont été également modélisées e en se basant surle modèle VHD-AMS de l’AOP. / This work is dealing with the modelling of analogue and mixed signal circuits. Moreprecisely, we focus on modelling the circuits of an analogue front-end which is used in down-holedrilling industry for instrumentation and measurement purposes. This research had as a goal tomodel the temperature increasing effect in the behaviour of each circuit of the considered frontend.The studied circuits belong to the family of “conventional” circuits. Most of these circuitsoperate in a temperature which does not exceed 125°C. Even if the behaviour of the circuit changesdue to an increasing of the temperature, there are some well-know techniques that enable thecompensation of such effects. However, in order to obtain a precise simulation in the design phase,it is very important to have accurate models that describe the temperature increasing effect. Asmost of the commercial circuits models are written in SPICE, it is necessary first to review theaccuracy of SPICE models in high temperature (HT). This work focus on a specific circuit: theoperational amplifier (opamp). This device is present in many instrumentation circuits. Obtainingan accurate op-amp model in HT will help us develop accurate models of these circuits byconsidering their architectural description which is based on the opamp model.The work starts with the study of the structure of the SPICE model of the considered opamp.This study enables us to confirm the non-validity of the SPICE model in HT. The validity studyconsists in comparing the SPCE simulation results of two parameters (the voltage offset and thecommon mode rejection ratio) to measurement results. Moreover, we present an interpretation tothe difference that was observed in this comparison. After comparing different modellingapproaches, we select the behavioural modelling one. The VHDL-AMS was used to develop thenew precise opamp model in HT. The simulation is performance in Cadence/ADVanceMSenvironment. The representation of each opamp parameter is validated by a specific circuit. Thismodel is developed in two steps. In the first step, we develop an opamp model in which there is noconsideration of the temperature effect. In the second step, dependence of each parameter to thetemperature is described by a polynomial or exponential function. This function is the result of thefitting process of the measurement results. These equations are inserted in the VHDL-AMS model.All parameters are again validated in each temperature. The test-circuit is the same circuit used inthe experimental test of the opamp parameters. The average error between measurement andsimulation does not exceed 3.11%. In the last chapter, we simulate some circuits of the theanalogue front-end of an acquisition system. We simulate for example the effect of the temperatureeffect on the accuracy of a Wheatstone bridge. Three architecture of an instrumentation amplifierwere also modelled and simulated in different temperature of [20°C, 220°C] in the basis of thedeveloped opamp model.

I have worked on many projects, but there are several things that they all had in common. First, nearly all projects involved searching for the structural parameters that governed the macroscopic properties of the polymers and composite materials. A second common denominator is that even though my work was performed in an “academic context”, the goals were targeted toward industrial needs. Lastly, the methods and procedures were similar; they were all based on experimental results obtained for various scales of measurement (see Fig. 1). Hence, multi-scale modeling was very useful and beneficial for these projects. The models developed (mainly numerical and sometimes analytical) were initially derived from experimental evidence and then validated and improved with further experimentation. The refined models provided an efficient means of: (i) optimizing the composites according to specific needs, (ii) better understanding the hierarchical relations between the different scales, (iii) controlling the micro or meso structure and thereby the macroscopic properties. This study of the relations between structure and properties was performed on a wide variety of physical properties and materials. However, the electric and dielectric properties of composites constituted the major- ity of it and will be presented in this report. The remaining property investigations provided supplemental but valuable information. This work often requires altering various conventional experimental techniques or using well-known techniques for new purposes. I also developed, when needed, several unconventional but necessary measurement techniques. This report contains two major parts which are separated according to the nature of the fillers: Part I : Conducting fillers. In the first part, the main interest both for application and fundamental point of view, is related to the changes in properties in the vicinity of the sharp percolation transition. After a brief introduction to the percolation theory, this part will be subdivided in three chapters: Chapter 1. presents a numerical method that correlates the mesostructure to the macroscopic electrical properties both in two and three dimensions. Chapter 2. will show that an external variable (the mechanical stress) may largely alter the microstruc- ture of the percolating network within composites as revealed the macroscopic conductivity. The understanding of the mesoscale changes will be based on the chemical structure of the polymer matrix. Chapter 3. is devoted to the description of a unique case in term of percolation behavior, which made possible the control of the phase arrangement within the composite and thereby the control of the macroscopic resistivity. p. 2 Multiscale relationships in polymer–based heterogeneous systems. . . Part II : Insulating fillers. In the second part, the main interest is to obtain good electrical insulators, i.e. that can withstand large electric fields. This part thus starts with a brief introduction to the common failure mechanisms, associated with the dielectric breakdown and is also divided in three chapters: Chapter 4. is devoted to the description of a numerical simulation of the relationships between mesostructure and dielectric breakdown. Chapter 5. reveals the influence of the processing conditions of a composite utilized in the industry on the microstructure and the quantitative consequences on breakdown properties. Chapter 6. presents the aging of these composites under “real word” conditions which will further be compared to accelerated aging performed in controlled conditions, in the laboratory. A comparison of the two aging situations will furnish a quantitative understanding of the relative influence of the chemical and physical contributions to the aging process. This report will then be concluded with a description of the current and future projects.

Es wird ein Verfahren zur lokalisierten elektrochemischen Abscheidung metallischer Strukturen aus Kapillarsonden vorgestellt. Der experimentelle Aufbau, die Herstellung der Sonden, das Arbeiten im Nahfeld der Probe (Scherkraft-Abstandsdetektion)sowie die verschiedenen Beschaltungmöglichkeiten der elektrochemischen Zelle werden ausführlich beschrieben. Ergänzend zu den experimentellen Arbeiten werden einerseits numerische Simulationen gezeigt, die zur Veranschaulichung der Potentialverteilung in der Apexregion dienen und qualitativ beschreiben, wie sich das Schichtdickenprofil der abgeschiedenen Strukturen mit den einstellbaren Parametern (Elektrodenpotentiale, Spitze-Probe-Abstand) variieren läßt. Andererseits werden die verschiedenen Beschaltungsmöglichkeiten der Zelle anhand von Schaltungssimulationen verglichen und so die Wahl des günstigsten Arbeitspunktes für die in den Experimenten verwendete (bi)-potentiostatische Abscheidung diskutiert. Mit dieser Anordnung wurden lokalisiert Cluster in einer porösen Aluminiumoxidmembran deponiert und anschließend abgebildet. In weiteren Strukturierungsversuchen wurden Kupfer bzw. Gold lokalisiert elektrochemisch auf ITO abgeschieden, wobei das Schichtwachstum simultan optisch in Transmission beobachtet wurde. Es werden u.a. Strukturen erzeugt, deren laterale Abmessungen kleiner als der Kapillardurchmesser sind (Fokussierung, max. Verhältnis 8:1). Die derzeit kleinsten elektrochemisch erzeugbaren Strukturen haben eine laterale Ausdehnung von ca. 5 Mikrometern. / A method for the localized electrochemical deposition of metal structures using capillary tips is presented. The experimental set-up, the tip preparation, the distance detection in near-field operation (shear-force detection), as well as the different types of circuiting of the electrochemical cell are described in detail. In addition to the experimental work, numerical simulations for the qualitative visualization of the potential distribution around the apex region show, how the films thickness profile can be adjusted with the variable parameters (electrode voltages, tip-sample distance). Circuit simulations of the electrochemical cell allow to pre-estimate the optimum working conditions for the used (bi)-potentiostatic electrode set-up. With this method, clusters have been deposited in a thin film of porous alumin oxide and imaged in shear-force mode. Gold and copper structures have been deposited on ITO, while the film growth was observed optically. The lateral dimension of the deposited structures can be smaller than the inner diameter of the capillaries (maximum focus: 8:1). The smallest structures produced in this work have lateral dimensions of 5 micrometers.