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Les super-statoréacteurs sont des systèmes de propulsion aérobie à grande vitesse qui ne nécessitent pas d’éléments rotatifs pour comprimer l’écoulement d’air. Celui-ci est comprimé dynamiquement par un système d’admission intégré dans le véhicule, atteignant la pression et la température requises pour que la combustion puisse s’opérer dans la chambre de combustion. La chambre de combustion est traversée par un écoulement supersonique dans ce type de moteur, ce qui limite considérablement le temps disponible pour injecter le carburant, le mélanger avec un oxydant, enflammer le mélange obtenu et parvenir à une combustion complète. Les cavités peuvent être utilisées pour augmenter le temps de séjour sans perte excessive de pression totale et sont donc utilisées comme éléments de stabilisation dans les chambres de combustion supersonique. Cette thèse se concentre sur l’étude du mécanisme de stabilisation et des interactions chimie-turbulence dans le cas d’une injection pariétale de combustible dans un écoulement supersonique d’air vicié en amont d’une cavité carrée. Les conditions d’écoulement réactif à grande vitesse correspondantes sont examinées sur la base de simulations numériques d’un modèle de scramjet représentatif d’expériences effectuées précédemment à l’Université du Michigan. Les calculs sont effectués avec le solveur CREAMS, développé pour effectuer la simulation numérique d’écoulements multi-espèces réactifs compressibles sur des architectures massivement parallèles. Le solveur utilise des schémas numériques d’ordre élevé appliqués sur des maillages structurées et la géométrie de la chambre de combustion est modélisée à l’aide d’une méthode de frontières immergées (IBM). Les simulations LES font usage du modèle wall-adapting local eddy (WALE). Deux températures distinctes sont considérées dans l’écoulement entrant d’air vicié pour étudier la stabilisation de la combustion.Une attention particulière est accordée à l’analyse de la topologie et de la structure des écoulements réactifs, les régimes de combustion sont analysés sur la base de diagrammes standards de combustion turbulente. / Scramjet engines are high-speed air breathing propulsion systems that do not require rotating elements to compress the air inlet stream. The flow is compressed dynamically through a supersonic intake system integrated in the aircraft’s forebody, reaching the required pressure and temperature for combustion to proceed within the combustor in this kind of engine. The combustion chamber is crossed by a supersonic flow, which limits severely the time available to inject fuel, mix it with oxidizer, ignite the resulting mixture and reach complete combustion. Cavities can be used to increase the residence time without excessive total pressure loss and are therefore used as flame holders in supersonic combustors.This thesis focuses in studying the flame stabilization mechanism and turbulence-chemistry interactions for a jet in a supersonic crossflow (JISCF) of vitiated air with hydrogen injection upstream of a wall-mounted squared cavity. The corresponding reactive high-speed flow conditions are scrutinized on the basis of numerical simulations of a scramjet model representative of experiments previously conducted at the University of Michigan. The computations are performed with the high-performance computational solver CREAMS, developed to perform the numerical simulation of compressible reactive multi-component flows on massively-parallel architectures. The solver makes use of high-order precision numerical schemes applied on structured meshes and the combustion chamber geometry is modeled by using the Immersed Boundary Method (IBM) algorithm. The present set of computations is conducted within the LES framework and the subgrid viscosity is treated with the wall-adapting local eddy (WALE)model. Two distinct temperatures are considered in the inlet vitiated airstream to study combustion stabilization. Special emphasis is placed on the analysis of the reactive flow topology and structure,and the combustion regimes are analyzed on the basis of standard turbulent combustion diagrams.

Nanomateriais, incluindo as nanopartículas e nanotubos, tem sido extensivamente utilizados em diversas aplicações tecnológicas, devido principalmente às suas interessantes propriedades, advindas da alta relação área/volume. Para a efetiva aplicação destes materiais em dispositivos nanotecnológicos, no entanto, é crucial o desenvolvimento de sistemas altamente estáveis, que mantenham suas propriedades por longos períodos. Neste trabalho foi proposta uma rota sintética para a preparação de nanopartículas de ouro na presença de polieletrólitos e tióis numa só fase, juntamente com um estudo sistemático da estabilidade dos sistemas produzidos. Os espectros de UV-vis obtidos demonstraram a formação de nanopartículas de ouro, com banda plasmônica característica. As nanopartículas foram também visualizadas por imagens de microscopia de Transmissão. Análise de espectroscopia na região do infravermelho (FTIR) mostraram as ligações químicas que ocorrem entre os materiais constituintes dos sistemas híbridos de AuNPs. O estudo de estabilidade das AuNps foi realizado com medidas de espalhamento de luz dinâmico (DLS) bem como por medidas de UV-vis, o que permitiu a obtenção do tipo de solução e condições mais estáveis. Através de análise estatística, por meio da análise de componentes principais (PCA), foi possível verificar quais fatores influenciam de forma significativa a estabilidade das diferentes soluções preparadas. / The use of nanomaterials - including nanoparticles and nanotubes - for technological applications has received tremendous attention in the last few years, mainly due to their unique, size-dependent properties. The proper application of such nanomaterials in technological devices, however, has been limited by parameters such as their physical or chemical stability. In this Master´s dissertation, we introduce a single step synthetic route for preparation of gold nanoparticles in the presence of polyelectrolytes and thiols, with emphasis on the stability of the nanomaterials under different storage conditions. Four different hybrid nanoparticles had been investigated, containing either PAH or PVA as the polymeric phase, in the presence of 3-AMP or 11-AMP thiols, respectively. After synthesis, the formation of the Au nanoparticles (AuNPs) was evidenced by UV-vis spectroscopy, upon appearance of a characteristic plasmonic band centered at ca. 510 or 540 nm, depending on the stabilizing agents used. The AuNPs were also investigated via TEM images. FTIR analyses evidenced that electrostatic interactions occurred between the thiols and the polyelectrolytes, within the hybrid nanoparticles structure. The stability of the four different systems was detailed investigated using UV-Vis spectroscopy, dynamic light scattering (DLS), and visual analyses. The data pointed to the higher stability presented by the AuNps stabilized with PAH in the presence of 3-AMP (PAH/3-AMP AuNPs). In contrast, the AuNPs stabilized with PVA exhibited the lowest stability. This feature was corroborated by statistical analysis, using principal component analysis (PCA), through which was possible to identify the main factor affecting AuNPs stability.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Alfred P. Sloan School of Management, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY. / Bibliography: leaves 227-234. / by Nathan Blair Forrester. / Ph.D.

During recessions, fiscal, monetary and other credit provision policies are used together to combat falling consumption levels and stabilize output. Most such counter-cyclical stabilization policies are deemed effective when households use provided credit or cash towards raising consumption. Hence, a deep understanding of consumer finance is central to understanding how and when such counter-cyclical stabilization policies work, and when they do not. In my dissertation, I focus primarily on one set of stabilization policies; namely fiscal stimulus. I provide particular empirical and theoretical insight into how consumers manage their finances and in particular liquidity levels, and how this behavior is connected to the effectiveness of fiscal policy during balance sheet recessions. I also discuss how the definition of effectiveness itself may need to undergo some revisions as applied to a balance sheet recession. Chapter 1 ``Heterogeneity in effectiveness of fiscal stimulus: The Economic Stimulus Payments of 2008" empirically investigates regional heterogeneity in the effectiveness of fiscal rebates during recessions characterized by housing crises. While general estimates of the effectiveness have been measured in previous literature, the state dependence of such effectiveness to the particular type of business cycle state (for example depth of regional housing crisis) is unknown. I first provide a description of the 2008 recession, and the history of recent fiscal policies along with the institutional arrangement of the fiscal stimulus policies enacted during the time. I next review the relevant empirical literature on fiscal policy effectiveness. I then describe the empirical methodology to estimate the effectiveness of fiscal rebate policies in 2008 and their regional heterogeneity. Using a special module of the Nielsen Consumer Panel which surveys households about their 2008 Economic Stimulus Payments, I show that households' marginal propensity to consume (MPC) out of these rebates was significantly lower in zipcodes with larger declines in housing prices. This pattern holds for both households with liquid assets and for those without. This highlights a novel finding compared to the previous literature; fiscal policy effectiveness is not explained solely by the behavior of households without liquid assets. These findings are not caused by differences in socio-economic and other observable characteristics and are robust to the use of a topology based instrument for housing price changes. Finally, I show that the results are driven by the difference in reported vs. revealed preference for reported savers and deleveragers in the hardest hit areas. Chapter 2 ``Policy and Theoretical Implications of Regional Heterogeneity in Fiscal Stimulus Effectiveness" investigates how the findings in Chapter 1 square with policy implications and consumption theory. On the policy side, I discuss how this result creates a policy dilemma, where fiscal stimulus may have been least effective in stimulating nondurable consumption in precisely the regions experiencing the worst recession. This underscores potential tradeoffs between the utilitarian and aggregate demand stabilization motives for rebate provision and the need to add nuance to the definition of fiscal policy effectiveness. On the theory side, I revisit the theoretical consumption literature and describe its predictions for MPC in a time of lower incomes and wealth. In particular, I look at how the negative relation between MPC and house price decline is at odds with the predictions of canonical buffer-stock models, which predict a higher MPC in worse affected regions. Next, I build a state of the art heterogeneous agent life cycle model, which features adjustment costs, long term debt and a default option, and calibrate it to regional variation in housing price declines, unemployment risk and income declines. I discuss newer mechanisms which could potentially match the empirical results. In reality, I show that even such a model substantially overestimates the effectiveness of fiscal stimulus in the worst affected regions. I explore the reasons behind such a mismatch, including the lack of marginal deleveraging in the model. Finally, I use data from the Michigan Survey of Consumers to rule out regional variation in permanent expectations as a key variable which could reconcile the findings in the data. Overall, the findings remain unreconciled with standard consumption theory, even after the augmentation of modern and realistic elements. Chapter 3 ``Evolution of Hand to Mouth Households (2007-09) and Lessons" continues on the theme of household liquidity which has been analyzed significantly to understand fiscal policy. A key parameter in the previous literature has been the proportion of illiquid households with housing wealth (also called wealthy hand to mouth households) who are important in understanding fiscal policy effectiveness. Two separate strands of the literature have emphasized either the role of permanent characteristics or income and wealth shocks (circumstance) in determining such status. In light of this, I document three new and robust findings. First, the overall proportion of such wealthy hand to mouth households stayed constant during the early years of the Great Recession. Second, there was massive underlying movement between various groups underneath the overall numbers. Third, households who built liquidity buffers had significantly larger losses to housing wealth and smaller losses to permanent income expectations. They also achieved this improvement in liquidity through methods other than the extraction of illiquid assets. This implies households who build liquidity buffers during housing crisis recessions do so through cutting consumption sharply. Taken together, these findings imply a) that both circumstantial and characteristics views on household liquidity are important, and b) that consumption models with net illiquid assets cannot match central facts for balance sheet recessions. This is because they predict households building liquidity buffers through extraction of illiquid wealth, which is unavailable during such recessions. In contrast, models with asset valuation effects do a better job of matching the liquidity management decisions of households. The goal of my research is to inform debates on fiscal policy effectiveness and the linkages to household liquidity. Future recessions with limitations on conventional monetary policy will especially be important times when these debates will play out. I hope this research provides useful information in the design and analysis of future counter-cyclical fiscal policies.

Digitized by Kansas Correctional Industries

The aim of this thesis is to identify and follow-up the analysis of job satisfaction, motivation and incentive structure of the staff at TÜV SÜD with empirical research and subsequent evaluation of the current situation and propose possible actions. The paper describes a style of personal work, especially those areas that contribute to the motivation of employees and subsequent stabilization. The next step is an analysis of satisfaction and motivation of employees using a questionnaire, the survey results are then evaluated there are given possible solutions for improvement.

Ce manuscrit est dédié à l'étude de la stabilité et la stabilisation en temps fini des systèmes dynamiques interconnectés et problème de consensus en temps fini. Après une large introduction, la première partie de ce mémoire se focalise sur la stabilité et stabilisation en temps fini des systèmes dynamiques perturbés et des systèmes dynamiques interconnectés. La deuxième partie de cette thèse est consacrée aux problèmes de : consensus en temps fini, consensus moyen en temps fini et stabilisation en temps fini des systèmes multi-agents. Cette notion a été abordé en ciblant les systèmes dynamiques contrôlés non linéaires et complexes de type avec et sans terme de dérive et affine en la commande. Des protocoles sont mis en exergue résolvant les problèmes de consensus/formation en temps fini entre les états de tels systèmes. De nombreuses applications avec des simulations permettent de confirmer les protocoles proposés. / This manuscript is dedicated to the study of finite time stability and stabilization of interconnected dynamical systems and finite time consensus problem. After a general introduction, the first part of this thesis focuses on finite time stability and stabilization of perturbed systems and interconnected systems. The second part of this thesis is devoted to the problems of: finite-time consensus, average consensus and finite time stabilization of multi-agent systems. This concept has been addressed by targeting non-linear controlled dynamical systems: with and without drift term. Some protocols are proposed to solve the finite time consensus problem. Many applications and simulations are illustrated.

A fast emerging technology in the microelectronics field is bottom-up self-assembly of computer circuitry. A promising method to develop nanoelectronic devices through bottom-up self-assembly is the implementation of DNA-based technologies. Using DNA to create nanoelectronic devices is advantageous because of its already well understood base-paring and annealing qualities. These base-pairing and annealing qualities can be used to design and construct DNA nanostructures called DNA origami. DNA origami are specially designed structures made from single stranded DNA. Short single stranded DNA oligonucleotides called staple strands attach to a large single stranded DNA called a DNA scaffold. DNA staple strands and DNA scaffold anneal to each other and fold into DNA origami. Constructing DNA origami is advantageous because structures can be made in a single folding step. In particular, bar-shaped DNA origami has proven to be a promising structure for nanoelectronics fabrication. Here, I present new research done to improve bar-shaped DNA origami design and fabrication for constructing bottom-up self-assembled templates for nanomaterial surface attachment. Furthermore, this work presents new methods for DNA origami agarose gel purification with the help of the DNA stabilizing molecule, 4'-aminomethyltrioxsalen (AMT). AMT is a photoreactive molecule that intercalates DNA and creates covalent crosslinks when irradiated by short wavelength ultraviolet light. Also, this work contains new research on a synthesized crosslinker and its role with AMT in nanoparticle surface seeding on DNA origami nanowire templates. Through its crosslinking properties, AMT serves as a DNA origami stabilizing molecule and also shows potential for seeding nanomaterials.

acase@tulane.edu / Worldwide, more than two billion people rely on onsite sanitation technologies for excreta treatment and/or disposal. The proper management of domestic septage remains a challenge in most cities in developing countries. A field experiment was conducted in Kinshasa/DR Congo from June 2013 to September 2015 to explore the effectiveness of lagoon treatment for the disinfection and the stabilization of domestic septage. Four lagoons were designed by combining two design factors: Total Solids content (< 5% versus 8% - 12%) and the protection from rainfall (Yes versus No). Each lagoon was a truncated pyramid with a usable volume of 28 m3 and 3m depth. The monitoring of pathogens inactivation was conducted from September 2014 over 12,4 months using coliforms bacteria and Ascaris lumbricoides eggs in sentinel chambers as indicator organisms, respectively with the multiple tubes technique and the Tulane Method. Local climate conditions and abiotic characteristics of the stored septage were monitored monthly. Four-log reduction of fecal coliforms organisms were observed within 10 months of septage storage in the two types of lagoons. At the end of this study, 3-log and less than 2-log reductions of Ascaris eggs were observed, respectively in the lagoons with high and low solids content. The inactivation curve of Ascaris eggs was characterized by a lag phase with a slight inactivation followed by an active inactivation phase. The inactivation rate constants for the active phase were 0.071 and 0.034 day-1, respectively in the lagoons with high and low solids content. Multiple linear regression model showed that the storage time, pH, and TS were significantly associated with percent Ascaris eggs inactivation. Trace elements concentrations in the final product were below threshold ceiling values for their reuse in agriculture. Total volatile solids concentration reduction in the lagoons with high solids content was below the stabilization limit set at 38% by USEPA. In conclusion, lagoon storage of domestic septage with at least 8% TS for 12 to 15 months is an effective option for the disinfection of domestic septage under the conditions of this study. The resulting biosolids constitute a value-added product which can be safely reused in agriculture. / 1 / Konde, Nkiama N.