Zugl.: Konstanz, Univ., Diss., 2008

Regensburg, Univ., Diss., 2008.

Universiẗat, Diss., 2003--Freiburg (Breisgau).

Pour les applications radioastronomiques, l'interface entre les mondes analogique et numérique est primordiale. Les convertisseurs analogique-numérique (CAN) doivent atteindre une forte résolution et un taux d'échantillonnage de plus en plus élevé pour numériser la plus grande bande passante possible. Pour le futur radiotélescope géant international SKA (Square Kilometer Array), la bande passante requise s'étend de 100 à 1500 MHz. L'objectif de ce mémoire est de concevoir et réaliser un CAN avec la technologie Qubic4X 0,25 µm en SiGeC, capable de dépasser le giga échantillon par seconde (GS/s) pour numériser toute la bande passante, pour des réseaux phasés denses. Deux études de CAN font l'objet de cette thèse. Dans le cadre de ce projet, nous avons analysé les différents blocs afin de minimiser les erreurs statiques et dynamiques pour une architecture parallèle 6 bits. Un premier CAN 6~bits en BiCMOS fonctionnant à une cadence de 1 GS/s a été étudié, réalisé et testé. Les simulations « post-layout » montrent un nombre de bits effectif de 4,6 bits pour une fréquence d'entrée de 400 MHz. La conception du masque permet de tester la puce. Ainsi, la sortie permet de valider le design. Les tests démontrent que le CAN opère à une fréquence maximale de 850 MS/s avec une bande passante de 400~MHz. Cependant, des erreurs persistent empêchant l'utilisation du circuit en raioastronomie. Le CAN consomme 2 Watts. Cette forte consommation est due aux interfaces d'entrées-sorties. Le second CAN bipolaire 6 bits fonctionne à une cadence de 3 GS/s. Ce convertisseur à architecture parallèle est entièrement conçu avec des topologies différentielles bipolaires. La partie numérique utilise une logique à émetteur couplé (ECL). Nous obtenons ainsi pour le second CAN une cadence de conversion élevée. Les simulations « post-layout » montrent que le CAN peut fonctionner à une fréquence de 3 GS/s, nous obtenons ainsi une bande passante de 1400 MHz. Les résultats dynamiques indiquent un nombre effectif de 5 bits pour une consommation de 3 Watts. / For applications in radio astronomy, the interface between the analog and digital domains is of primary concern. Analog-to-Digital Converters (ADC) must be capable of high resolution and extremely high sampling speeds in order to achieve the largest possible band width. For the future giant international radio telescope called the Square Kilometer Array (SKA), the bandwidth required is between 100 and 1500~MHz. The subject of the present thesis is to design and manufacture an ADC using the Qubic4X 0.25 µm technology in SiGeC capable of surpassing giga-samples per second (GS/s) in order to digitise the entire passband for dense phased-arrays. Two ADC designs are presented here. For this project, we analysed different design blocks with the goal of reducing static and dynamic errors in a 6-bit parallel architecture. The first 6-bit ADC which was designed, manufactured, and tested, was in BiCMOS and operated at 1 GS/s. The post-layout simulations showed the effective number of bits to be 4.6 bits with a 400 MHz input frequency. The mask design allowed for testing the chip. In this way, the output validates the design. Tests show that the ADC operates up to a maximum frequency of 850 MS/s with a passband of 400 MHz. However, there are some errors which make the current circuit unusable for astronomy purposes. The ADC runs on 2 Watts. The high power consumption is due to the input and output stages. The second 6-bit bipolar ADC operates at 3 GS/s. It is designed with a parallel architecture entirely using a bipolar differential topology. The digital part uses Emitter Coupled Logic (ECL). With this second chip, we obtain high speed conversion. Post-layout simulations show that the ADC can operate up to 3 GS/s, and we thus obtain a passband of 1400 MHz. Dynamic measurements indicate an effective number of bits of 5 bits with a power consumption of 3 Watts.

Les appareils de chauffage électrique, qui peuvent paraître relativement simples au premier abord car constitués uniquement d’une résistance chauffante électrique encapsulée dans une enveloppe métallique, sont en réalité des échangeurs de chaleur beaucoup plus complexes. Outre la partie régulation, en charge de déterminer à chaque instant la quantité d’énergie à apporter à la pièce pour fournir les températures d’air souhaitées, l’appareil doit assurer une uniformité des températures et des vitesses d’air cohérentes avec le confort thermique désiré et ce, quels que soient son mode de fonctionnement et les conditions thermiques extérieures. De cette bonne répartition des températures et des vitesses d’air découlera un bon niveau de confort thermique, gage d’une consommation énergétique sobre et maîtrisée. L’objectif de la thèse est donc de mieux comprendre dans une première phase les phénomènes thermo-aérauliques agissant à l’échelle du radiateur et dans une deuxième phase ceux agissant à l’échelle de la pièce. Pour améliorer cette compréhension, un outil de simulation numérique qui pourra servir à la conception des radiateurs par la société CAMPA a été développé. / The electric heating devices, which can seem relatively simple at first sight because composed only by an electric heating resistance in a metallic box, are in reality much more complex heat exchangers. Besides the regulation process part the role of which is to determine at every moment the quantity of energy to bring to the room to supply the desired temperatures of air, the device has to ensure a uniformity of temperatures and velocities of air in agreement with the thermal comfort wished, whatever his way of functioning and the outside thermal conditions. This good distribution of temperatures and velocities of air will give a good thermal comfort level which is the condition of a sober and controlled energy consumption. The objective of this thesis is thus to better understand in a first phase the thermo-aeraulics phenomena acting on the scale of the radiator and in the second phase those acting on the scale of the room. To improve this understanding, a tool of digital simulation which can be used to the conception of radiators by the company CAMPA has been developed.

Chapter 1: When Environmental Subsidies Backfire: The Case of Black Liquor and the Alternative Fuel Mixture Tax Credit: In 2005, the US government introduced the Alternative Fuel Mixture Tax Credit (AFMTC), which paid fifty cents/gallon for alternative fuel that was mixed and burned with traditional fuel. The American chemical pulp industry, which has traditionally burned ‘Black Liquor’, a residue of the pulping process, was able to make large claims on this subsidy in 2009 by mixing diesel fuel into a process where it was not required. This scenario exhibits two main downfalls of environmental subsidies: (i) the majority of the subsidy is paid to free-riders, and (ii) there are strong incentives towards overproduction and increased pollution. In this paper, the value of the AFMTC per tonne of chemical pulp is computed and used in a simulation using the Global Forest Products Model (Buongiorno, 2001) to calculate the effects of the AFMTC on the American and Canadian chemical pulp industries. The simulation suggests that the total amount paid to the American chemical pulp industry was US$7.63 billion, that American chemical pulp production rose by 2.5 million tonnes from the baseline, and Canadian production and exports to the US fell by 285,000 and 255,000 tonnes respectively, costing Canadian chemical pulp producers US$132 million in lost production. Using Canadian chemical pulp production and pollutant release data, production/release averages were developed. These averages suggest that the increase in American chemical pulp production led to significant increase in releases of greenhouse gases, hydrogen sulfide, sulfur oxides, nitrogen oxides and particulate matter. Chapter 2: The Alternative Fuel Mixture Tax Credit and the Pulp and Paper Green Transformation Program: A Policy Comparison: In 2009, chemical pulp mills in the US and Canada were able to take advantage of two subsidy programs that paid mills fifty cents for every gallon of ‘Black Liquor’ burned during the pulping process. Black Liquor is a residue product from the production of chemical pulp, and is traditionally used as a fuel in further pulp production. These subsidies were the Alternative Fuel Mixture Tax Credit (AFMTC) in the US and the Pulp and Paper Green Transformation Program (PPGTP) in Canada. Even though the AFMTC was a subsidy that applied to many industries, and the PPGTP was only available to chemical pulp mills, in the context of the chemical pulp industry only, the subsidies were almost identical: Both paid mills the same amount for undertaking the same activity, and mills were able to claim the subsidies for roughly the same amount of time. The key difference between the two programs was stipulations on how the money was to be spent. In the US, the AFMTC was a refundable tax credit, and simply another source of revenue for a recipient mill. In Canada, a recipient of PPGTP funds was required to spend the money on some form of capital investment that would increase energy efficiency or lower pollution emissions from the mill. In this paper, we develop a theoretical model with a representative chemical pulp mill in order to compare the effects that these two subsidies would have on the mill’s production of pulp (and in turn its production and use of black liquor), and its decision in whether to invest in a one-time capital improvement that would increase energy efficiency at the mill. The results from this model show that the PPGTP was a more effective policy than the AFMTC, in that it encouraged increased investment in energy efficiency, whereas the AFMTC did not. However, the PPGTP provides incentives to increase production, similar to the AFMTC, in two out of three possible outcomes. Even though the PPGTP is shown to be more effective than the AFMTC, it still exhibits several properties inherent in a second-best policy - because the subsidy is tied to production, it encouraged increased production, and may not have allocated funding in an efficient manner. Chapter 3: Naming, Shaming, and Abatement: Do Published ‘Top Emitter’ Lists Provide Incentive for Increasing Pollution Prevention Activities? Several works have measured the effects that publically disclosed pollutant release information has on the firms and facilities reporting the information. Most of these studies quantify the negative response that the information garners with the media, through some measure of media coverage, and measure the negative impact that this attention has on the firm; for example, by showing a negative effect on the respective company’s publically traded stock performance. Subsequent studies have then shown how these negative impacts from publicity cause firms to report lower emissions levels in following years. What is currently missing from this body of literature, however, is an examination of the step in between the firm receiving negative press and reporting lower emissions, namely, increased pollution abatement efforts on behalf of the publically labeled facility. In this paper, we attempt to gain a better understanding of this relationship by examining Canadian self-reported facility level data on pollution prevention activities from the National Pollutant Release Inventory. Two consistent samples of data are used to empirically test the effects that ‘Top Ten’ emitter lists, published by Environment Canada in the late 1990’s, had on the number of pollution prevention activities undertaken by facilities in the following year. The results from this work were inconclusive: Between these two samples, there was a noticeable decrease in the amount of pollution prevention activities reported in years after the cessation of the Top Ten publications. Under certain model specifications, a facility that was labeled as a Top Ten emitter is estimated to have 20% more pollution prevention activities undertaken compared to a facility that was not so labeled. It was also shown that a firm that reported new pollution abatement activities also had a significant reduction in releases. This finding, along with the decreasing trend in reported activities, raises a significant policy issue, as measures that clearly reduce reported emissions are being reported with less frequency in Canada.

This project was focused on the creation of a gold-coated grating structure capable of inducing a surface plasmon polariton within the mid-infrared region, enhancing emissions at specific wavelengths based on the grating periodicity. The grating structure was formed on a silicone elastomer, polydimethylsiloxane (PDMS), in order to give the structure, the ability to have the periodicity dimensions of the grating altered by applying a stress, thereby changing the location of the emission enhancement, giving the device the potential to be used as an infrared strain sensor. Creation of the structure employed a top-down, micro-scale fabrication technique referred to as Direct Laser Writing (DLW). Using a light-sensitive, negative-tone photoresist material, a grating was patterned onto a glass substrate via photopolymerization, in which areas exposed to an ultraviolet (UV) laser were rendered insoluble by forming cross-links on the portions of the resist which interacted with the UV source. This grating was then placed under a custom-designed mold which was then filled with liquid PDMS and cured for 3 hours at 60°C to cure (harden or cross-link) and leaving an inverse elastomer pattern behind once the cured PDMS was peeled off the substrate. Upon coating the structure with a ~80 nm thick layer of gold, a Fourier Transform infrared (FTIR) spectrometer was used to measure the thermal emissions spectrum of the sample grating at a high temperature (~200°C) and under different strains. These spectra were then analyzed to look for selective emission enhancements caused by the grating structure due to the inducing of a surface plasmon polariton (SPP), as well as changes in the location and nature of these enhancements based on applied strains. Final results showed two sets of enhancement behaviors with the application of uniaxial strain: a shifting of the region of peak emission enhancement to higher wavelengths, and a broadening of the region of enhancement. However, more testing is needed in order to determine the precise causes of the behavior and to quantify it in such a way that it could be turned into a functioning sensor device.

In the electroplating process, dissolved metal cations are reduced by electrical current to a form a coherent metal coating on an electrode. Therefore, electroplating is primarily applied to modify the surface properties of an object (e.g. abrasion and wear resistance, corrosion protection, lubricity, aesthetic qualities, etc.), but also be applied to build up high aspect ratio structures on undersized parts or to form devices by electroforming. Compared with other common MEMS (microelectromechanical systems) metal device fabrication techniques, such as vapor depositions, electroplating has several outstanding advantages. First, the fabrication process is cost-efficient because electroplating process can be set up easily without complex and expensive facilities. Second, the fabrication condition of electroplating is less demanding and does not require high temperature or low pressure. Furthermore, the process is applicable to making various features consisting of nanometer to millimeter scale particles, wires, and films. Thus, in this thesis, based on the design requirements of electrospray emitters and environmental sensors, the electroplating method was chosen to fabricate micro- and nanoscale structures for such applications. Electrospray is an atomization technique by which an electrically conductive liquid through a small capillary is charged with high voltage (kV) and ejected to a ground electrode. To minimize the electric field edge effect of the emitter nozzles to get even electro-hydrodynamic pulling force on the liquid among the nozzles and minimize variation from one emitter to another, the device needs to have the viscous pressure drop across each nozzle dominant over the electro-hydrodynamic pulling force. Therefore, embedded structures that can create high flow impedance are desirable to achieve uniform feeding of low flow rate of liquid to each emitter. We designed and fabricated in-plane metallic electrospray devices with an embedded array of micropillars within a microchannel by photolithography and electroplating. The novelty of the proposed research lies in its embedded flow restriction structure, scalability, and ease of fabrication. The formation of jets as well as the flexing capability of the emitter was achieved. The other application of electroplating was demonstrated in the fabrication of environmental sensors. Utilizing a pulsed electroplating method, Co-Cu metal alloy films were prepared and Cu was selectively etched to fabricate nanoporous electrodes which could be used to measure both absolute levels and changes of phosphate concentration in aqueous environments. The formation of cobalt phosphate compound could be used for the detection. The increased surface area and relatively simple fabrication protocols make the proposed method attractive and promising for many environmental sensing applications.

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